]> Pileus Git - ~andy/linux/blobdiff - kernel/trace/trace.c
tracing: Add alloc/free_snapshot() to replace duplicate code
[~andy/linux] / kernel / trace / trace.c
index c8a852a55db4cb3dd29dd037deed7e879584b090..906049c0af9000fd75603f10d3fe801c3234db91 100644 (file)
@@ -47,7 +47,7 @@
  * On boot up, the ring buffer is set to the minimum size, so that
  * we do not waste memory on systems that are not using tracing.
  */
-int ring_buffer_expanded;
+bool ring_buffer_expanded;
 
 /*
  * We need to change this state when a selftest is running.
@@ -121,12 +121,14 @@ static int tracing_set_tracer(const char *buf);
 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
 static char *default_bootup_tracer;
 
+static bool allocate_snapshot;
+
 static int __init set_cmdline_ftrace(char *str)
 {
        strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
        default_bootup_tracer = bootup_tracer_buf;
        /* We are using ftrace early, expand it */
-       ring_buffer_expanded = 1;
+       ring_buffer_expanded = true;
        return 1;
 }
 __setup("ftrace=", set_cmdline_ftrace);
@@ -147,6 +149,15 @@ static int __init set_ftrace_dump_on_oops(char *str)
 }
 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
 
+static int __init boot_alloc_snapshot(char *str)
+{
+       allocate_snapshot = true;
+       /* We also need the main ring buffer expanded */
+       ring_buffer_expanded = true;
+       return 1;
+}
+__setup("alloc_snapshot", boot_alloc_snapshot);
+
 
 static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
 static char *trace_boot_options __initdata;
@@ -195,27 +206,15 @@ cycle_t ftrace_now(int cpu)
        u64 ts;
 
        /* Early boot up does not have a buffer yet */
-       if (!global_trace.buffer)
+       if (!global_trace.trace_buffer.buffer)
                return trace_clock_local();
 
-       ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
-       ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
+       ts = ring_buffer_time_stamp(global_trace.trace_buffer.buffer, cpu);
+       ring_buffer_normalize_time_stamp(global_trace.trace_buffer.buffer, cpu, &ts);
 
        return ts;
 }
 
-/*
- * The max_tr is used to snapshot the global_trace when a maximum
- * latency is reached. Some tracers will use this to store a maximum
- * trace while it continues examining live traces.
- *
- * The buffers for the max_tr are set up the same as the global_trace.
- * When a snapshot is taken, the link list of the max_tr is swapped
- * with the link list of the global_trace and the buffers are reset for
- * the global_trace so the tracing can continue.
- */
-static struct trace_array      max_tr;
-
 int tracing_is_enabled(void)
 {
        return tracing_is_on();
@@ -339,8 +338,8 @@ unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
  */
 void tracing_on(void)
 {
-       if (global_trace.buffer)
-               ring_buffer_record_on(global_trace.buffer);
+       if (global_trace.trace_buffer.buffer)
+               ring_buffer_record_on(global_trace.trace_buffer.buffer);
        /*
         * This flag is only looked at when buffers haven't been
         * allocated yet. We don't really care about the race
@@ -351,6 +350,196 @@ void tracing_on(void)
 }
 EXPORT_SYMBOL_GPL(tracing_on);
 
+/**
+ * __trace_puts - write a constant string into the trace buffer.
+ * @ip:           The address of the caller
+ * @str:   The constant string to write
+ * @size:  The size of the string.
+ */
+int __trace_puts(unsigned long ip, const char *str, int size)
+{
+       struct ring_buffer_event *event;
+       struct ring_buffer *buffer;
+       struct print_entry *entry;
+       unsigned long irq_flags;
+       int alloc;
+
+       alloc = sizeof(*entry) + size + 2; /* possible \n added */
+
+       local_save_flags(irq_flags);
+       buffer = global_trace.trace_buffer.buffer;
+       event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc, 
+                                         irq_flags, preempt_count());
+       if (!event)
+               return 0;
+
+       entry = ring_buffer_event_data(event);
+       entry->ip = ip;
+
+       memcpy(&entry->buf, str, size);
+
+       /* Add a newline if necessary */
+       if (entry->buf[size - 1] != '\n') {
+               entry->buf[size] = '\n';
+               entry->buf[size + 1] = '\0';
+       } else
+               entry->buf[size] = '\0';
+
+       __buffer_unlock_commit(buffer, event);
+
+       return size;
+}
+EXPORT_SYMBOL_GPL(__trace_puts);
+
+/**
+ * __trace_bputs - write the pointer to a constant string into trace buffer
+ * @ip:           The address of the caller
+ * @str:   The constant string to write to the buffer to
+ */
+int __trace_bputs(unsigned long ip, const char *str)
+{
+       struct ring_buffer_event *event;
+       struct ring_buffer *buffer;
+       struct bputs_entry *entry;
+       unsigned long irq_flags;
+       int size = sizeof(struct bputs_entry);
+
+       local_save_flags(irq_flags);
+       buffer = global_trace.trace_buffer.buffer;
+       event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
+                                         irq_flags, preempt_count());
+       if (!event)
+               return 0;
+
+       entry = ring_buffer_event_data(event);
+       entry->ip                       = ip;
+       entry->str                      = str;
+
+       __buffer_unlock_commit(buffer, event);
+
+       return 1;
+}
+EXPORT_SYMBOL_GPL(__trace_bputs);
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+/**
+ * trace_snapshot - take a snapshot of the current buffer.
+ *
+ * This causes a swap between the snapshot buffer and the current live
+ * tracing buffer. You can use this to take snapshots of the live
+ * trace when some condition is triggered, but continue to trace.
+ *
+ * Note, make sure to allocate the snapshot with either
+ * a tracing_snapshot_alloc(), or by doing it manually
+ * with: echo 1 > /sys/kernel/debug/tracing/snapshot
+ *
+ * If the snapshot buffer is not allocated, it will stop tracing.
+ * Basically making a permanent snapshot.
+ */
+void tracing_snapshot(void)
+{
+       struct trace_array *tr = &global_trace;
+       struct tracer *tracer = tr->current_trace;
+       unsigned long flags;
+
+       if (in_nmi()) {
+               internal_trace_puts("*** SNAPSHOT CALLED FROM NMI CONTEXT ***\n");
+               internal_trace_puts("*** snapshot is being ignored        ***\n");
+               return;
+       }
+
+       if (!tr->allocated_snapshot) {
+               internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n");
+               internal_trace_puts("*** stopping trace here!   ***\n");
+               tracing_off();
+               return;
+       }
+
+       /* Note, snapshot can not be used when the tracer uses it */
+       if (tracer->use_max_tr) {
+               internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n");
+               internal_trace_puts("*** Can not use snapshot (sorry) ***\n");
+               return;
+       }
+
+       local_irq_save(flags);
+       update_max_tr(tr, current, smp_processor_id());
+       local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot);
+
+static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
+                                       struct trace_buffer *size_buf, int cpu_id);
+static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);
+
+static int alloc_snapshot(struct trace_array *tr)
+{
+       int ret;
+
+       if (!tr->allocated_snapshot) {
+
+               /* allocate spare buffer */
+               ret = resize_buffer_duplicate_size(&tr->max_buffer,
+                                  &tr->trace_buffer, RING_BUFFER_ALL_CPUS);
+               if (ret < 0)
+                       return ret;
+
+               tr->allocated_snapshot = true;
+       }
+
+       return 0;
+}
+
+void free_snapshot(struct trace_array *tr)
+{
+       /*
+        * We don't free the ring buffer. instead, resize it because
+        * The max_tr ring buffer has some state (e.g. ring->clock) and
+        * we want preserve it.
+        */
+       ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
+       set_buffer_entries(&tr->max_buffer, 1);
+       tracing_reset_online_cpus(&tr->max_buffer);
+       tr->allocated_snapshot = false;
+}
+
+/**
+ * trace_snapshot_alloc - allocate and take a snapshot of the current buffer.
+ *
+ * This is similar to trace_snapshot(), but it will allocate the
+ * snapshot buffer if it isn't already allocated. Use this only
+ * where it is safe to sleep, as the allocation may sleep.
+ *
+ * This causes a swap between the snapshot buffer and the current live
+ * tracing buffer. You can use this to take snapshots of the live
+ * trace when some condition is triggered, but continue to trace.
+ */
+void tracing_snapshot_alloc(void)
+{
+       struct trace_array *tr = &global_trace;
+       int ret;
+
+       ret = alloc_snapshot(tr);
+       if (WARN_ON(ret < 0))
+               return;
+
+       tracing_snapshot();
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
+#else
+void tracing_snapshot(void)
+{
+       WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot);
+void tracing_snapshot_alloc(void)
+{
+       /* Give warning */
+       tracing_snapshot();
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
 /**
  * tracing_off - turn off tracing buffers
  *
@@ -361,8 +550,8 @@ EXPORT_SYMBOL_GPL(tracing_on);
  */
 void tracing_off(void)
 {
-       if (global_trace.buffer)
-               ring_buffer_record_off(global_trace.buffer);
+       if (global_trace.trace_buffer.buffer)
+               ring_buffer_record_off(global_trace.trace_buffer.buffer);
        /*
         * This flag is only looked at when buffers haven't been
         * allocated yet. We don't really care about the race
@@ -378,8 +567,8 @@ EXPORT_SYMBOL_GPL(tracing_off);
  */
 int tracing_is_on(void)
 {
-       if (global_trace.buffer)
-               return ring_buffer_record_is_on(global_trace.buffer);
+       if (global_trace.trace_buffer.buffer)
+               return ring_buffer_record_is_on(global_trace.trace_buffer.buffer);
        return !global_trace.buffer_disabled;
 }
 EXPORT_SYMBOL_GPL(tracing_is_on);
@@ -637,13 +826,14 @@ unsigned long __read_mostly       tracing_max_latency;
 static void
 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
-       struct trace_array_cpu *data = per_cpu_ptr(tr->data, cpu);
-       struct trace_array_cpu *max_data;
+       struct trace_buffer *trace_buf = &tr->trace_buffer;
+       struct trace_buffer *max_buf = &tr->max_buffer;
+       struct trace_array_cpu *data = per_cpu_ptr(trace_buf->data, cpu);
+       struct trace_array_cpu *max_data = per_cpu_ptr(max_buf->data, cpu);
 
-       max_tr.cpu = cpu;
-       max_tr.time_start = data->preempt_timestamp;
+       max_buf->cpu = cpu;
+       max_buf->time_start = data->preempt_timestamp;
 
-       max_data = per_cpu_ptr(max_tr.data, cpu);
        max_data->saved_latency = tracing_max_latency;
        max_data->critical_start = data->critical_start;
        max_data->critical_end = data->critical_end;
@@ -678,7 +868,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
        WARN_ON_ONCE(!irqs_disabled());
 
-       if (!tr->current_trace->allocated_snapshot) {
+       if (!tr->allocated_snapshot) {
                /* Only the nop tracer should hit this when disabling */
                WARN_ON_ONCE(tr->current_trace != &nop_trace);
                return;
@@ -686,9 +876,9 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
        arch_spin_lock(&ftrace_max_lock);
 
-       buf = tr->buffer;
-       tr->buffer = max_tr.buffer;
-       max_tr.buffer = buf;
+       buf = tr->trace_buffer.buffer;
+       tr->trace_buffer.buffer = tr->max_buffer.buffer;
+       tr->max_buffer.buffer = buf;
 
        __update_max_tr(tr, tsk, cpu);
        arch_spin_unlock(&ftrace_max_lock);
@@ -711,12 +901,12 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
                return;
 
        WARN_ON_ONCE(!irqs_disabled());
-       if (WARN_ON_ONCE(!tr->current_trace->allocated_snapshot))
+       if (WARN_ON_ONCE(!tr->allocated_snapshot))
                return;
 
        arch_spin_lock(&ftrace_max_lock);
 
-       ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
+       ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->trace_buffer.buffer, cpu);
 
        if (ret == -EBUSY) {
                /*
@@ -725,7 +915,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
                 * the max trace buffer (no one writes directly to it)
                 * and flag that it failed.
                 */
-               trace_array_printk(&max_tr, _THIS_IP_,
+               trace_array_printk_buf(tr->max_buffer.buffer, _THIS_IP_,
                        "Failed to swap buffers due to commit in progress\n");
        }
 
@@ -742,8 +932,74 @@ static void default_wait_pipe(struct trace_iterator *iter)
        if (trace_buffer_iter(iter, iter->cpu_file))
                return;
 
-       ring_buffer_wait(iter->tr->buffer, iter->cpu_file);
+       ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
+}
+
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+static int run_tracer_selftest(struct tracer *type)
+{
+       struct trace_array *tr = &global_trace;
+       struct tracer *saved_tracer = tr->current_trace;
+       int ret;
+
+       if (!type->selftest || tracing_selftest_disabled)
+               return 0;
+
+       /*
+        * Run a selftest on this tracer.
+        * Here we reset the trace buffer, and set the current
+        * tracer to be this tracer. The tracer can then run some
+        * internal tracing to verify that everything is in order.
+        * If we fail, we do not register this tracer.
+        */
+       tracing_reset_online_cpus(&tr->trace_buffer);
+
+       tr->current_trace = type;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+       if (type->use_max_tr) {
+               /* If we expanded the buffers, make sure the max is expanded too */
+               if (ring_buffer_expanded)
+                       ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
+                                          RING_BUFFER_ALL_CPUS);
+               tr->allocated_snapshot = true;
+       }
+#endif
+
+       /* the test is responsible for initializing and enabling */
+       pr_info("Testing tracer %s: ", type->name);
+       ret = type->selftest(type, tr);
+       /* the test is responsible for resetting too */
+       tr->current_trace = saved_tracer;
+       if (ret) {
+               printk(KERN_CONT "FAILED!\n");
+               /* Add the warning after printing 'FAILED' */
+               WARN_ON(1);
+               return -1;
+       }
+       /* Only reset on passing, to avoid touching corrupted buffers */
+       tracing_reset_online_cpus(&tr->trace_buffer);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+       if (type->use_max_tr) {
+               tr->allocated_snapshot = false;
+
+               /* Shrink the max buffer again */
+               if (ring_buffer_expanded)
+                       ring_buffer_resize(tr->max_buffer.buffer, 1,
+                                          RING_BUFFER_ALL_CPUS);
+       }
+#endif
+
+       printk(KERN_CONT "PASSED\n");
+       return 0;
 }
+#else
+static inline int run_tracer_selftest(struct tracer *type)
+{
+       return 0;
+}
+#endif /* CONFIG_FTRACE_STARTUP_TEST */
 
 /**
  * register_tracer - register a tracer with the ftrace system.
@@ -790,57 +1046,9 @@ int register_tracer(struct tracer *type)
        if (!type->wait_pipe)
                type->wait_pipe = default_wait_pipe;
 
-
-#ifdef CONFIG_FTRACE_STARTUP_TEST
-       if (type->selftest && !tracing_selftest_disabled) {
-               struct trace_array *tr = &global_trace;
-               struct tracer *saved_tracer = tr->current_trace;
-
-               /*
-                * Run a selftest on this tracer.
-                * Here we reset the trace buffer, and set the current
-                * tracer to be this tracer. The tracer can then run some
-                * internal tracing to verify that everything is in order.
-                * If we fail, we do not register this tracer.
-                */
-               tracing_reset_online_cpus(tr);
-
-               tr->current_trace = type;
-
-               if (type->use_max_tr) {
-                       /* If we expanded the buffers, make sure the max is expanded too */
-                       if (ring_buffer_expanded)
-                               ring_buffer_resize(max_tr.buffer, trace_buf_size,
-                                                  RING_BUFFER_ALL_CPUS);
-                       type->allocated_snapshot = true;
-               }
-
-               /* the test is responsible for initializing and enabling */
-               pr_info("Testing tracer %s: ", type->name);
-               ret = type->selftest(type, tr);
-               /* the test is responsible for resetting too */
-               tr->current_trace = saved_tracer;
-               if (ret) {
-                       printk(KERN_CONT "FAILED!\n");
-                       /* Add the warning after printing 'FAILED' */
-                       WARN_ON(1);
-                       goto out;
-               }
-               /* Only reset on passing, to avoid touching corrupted buffers */
-               tracing_reset_online_cpus(tr);
-
-               if (type->use_max_tr) {
-                       type->allocated_snapshot = false;
-
-                       /* Shrink the max buffer again */
-                       if (ring_buffer_expanded)
-                               ring_buffer_resize(max_tr.buffer, 1,
-                                                  RING_BUFFER_ALL_CPUS);
-               }
-
-               printk(KERN_CONT "PASSED\n");
-       }
-#endif
+       ret = run_tracer_selftest(type);
+       if (ret < 0)
+               goto out;
 
        type->next = trace_types;
        trace_types = type;
@@ -860,7 +1068,7 @@ int register_tracer(struct tracer *type)
        tracing_set_tracer(type->name);
        default_bootup_tracer = NULL;
        /* disable other selftests, since this will break it. */
-       tracing_selftest_disabled = 1;
+       tracing_selftest_disabled = true;
 #ifdef CONFIG_FTRACE_STARTUP_TEST
        printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
               type->name);
@@ -870,9 +1078,9 @@ int register_tracer(struct tracer *type)
        return ret;
 }
 
-void tracing_reset(struct trace_array *tr, int cpu)
+void tracing_reset(struct trace_buffer *buf, int cpu)
 {
-       struct ring_buffer *buffer = tr->buffer;
+       struct ring_buffer *buffer = buf->buffer;
 
        if (!buffer)
                return;
@@ -886,9 +1094,9 @@ void tracing_reset(struct trace_array *tr, int cpu)
        ring_buffer_record_enable(buffer);
 }
 
-void tracing_reset_online_cpus(struct trace_array *tr)
+void tracing_reset_online_cpus(struct trace_buffer *buf)
 {
-       struct ring_buffer *buffer = tr->buffer;
+       struct ring_buffer *buffer = buf->buffer;
        int cpu;
 
        if (!buffer)
@@ -899,7 +1107,7 @@ void tracing_reset_online_cpus(struct trace_array *tr)
        /* Make sure all commits have finished */
        synchronize_sched();
 
-       tr->time_start = ftrace_now(tr->cpu);
+       buf->time_start = ftrace_now(buf->cpu);
 
        for_each_online_cpu(cpu)
                ring_buffer_reset_cpu(buffer, cpu);
@@ -909,7 +1117,7 @@ void tracing_reset_online_cpus(struct trace_array *tr)
 
 void tracing_reset_current(int cpu)
 {
-       tracing_reset(&global_trace, cpu);
+       tracing_reset(&global_trace.trace_buffer, cpu);
 }
 
 void tracing_reset_all_online_cpus(void)
@@ -918,7 +1126,10 @@ void tracing_reset_all_online_cpus(void)
 
        mutex_lock(&trace_types_lock);
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
-               tracing_reset_online_cpus(tr);
+               tracing_reset_online_cpus(&tr->trace_buffer);
+#ifdef CONFIG_TRACER_MAX_TRACE
+               tracing_reset_online_cpus(&tr->max_buffer);
+#endif
        }
        mutex_unlock(&trace_types_lock);
 }
@@ -988,13 +1199,15 @@ void tracing_start(void)
        /* Prevent the buffers from switching */
        arch_spin_lock(&ftrace_max_lock);
 
-       buffer = global_trace.buffer;
+       buffer = global_trace.trace_buffer.buffer;
        if (buffer)
                ring_buffer_record_enable(buffer);
 
-       buffer = max_tr.buffer;
+#ifdef CONFIG_TRACER_MAX_TRACE
+       buffer = global_trace.max_buffer.buffer;
        if (buffer)
                ring_buffer_record_enable(buffer);
+#endif
 
        arch_spin_unlock(&ftrace_max_lock);
 
@@ -1026,7 +1239,7 @@ static void tracing_start_tr(struct trace_array *tr)
                goto out;
        }
 
-       buffer = tr->buffer;
+       buffer = tr->trace_buffer.buffer;
        if (buffer)
                ring_buffer_record_enable(buffer);
 
@@ -1053,13 +1266,15 @@ void tracing_stop(void)
        /* Prevent the buffers from switching */
        arch_spin_lock(&ftrace_max_lock);
 
-       buffer = global_trace.buffer;
+       buffer = global_trace.trace_buffer.buffer;
        if (buffer)
                ring_buffer_record_disable(buffer);
 
-       buffer = max_tr.buffer;
+#ifdef CONFIG_TRACER_MAX_TRACE
+       buffer = global_trace.max_buffer.buffer;
        if (buffer)
                ring_buffer_record_disable(buffer);
+#endif
 
        arch_spin_unlock(&ftrace_max_lock);
 
@@ -1080,7 +1295,7 @@ static void tracing_stop_tr(struct trace_array *tr)
        if (tr->stop_count++)
                goto out;
 
-       buffer = tr->buffer;
+       buffer = tr->trace_buffer.buffer;
        if (buffer)
                ring_buffer_record_disable(buffer);
 
@@ -1246,7 +1461,7 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
                          int type, unsigned long len,
                          unsigned long flags, int pc)
 {
-       *current_rb = ftrace_file->tr->buffer;
+       *current_rb = ftrace_file->tr->trace_buffer.buffer;
        return trace_buffer_lock_reserve(*current_rb,
                                         type, len, flags, pc);
 }
@@ -1257,7 +1472,7 @@ trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
                                  int type, unsigned long len,
                                  unsigned long flags, int pc)
 {
-       *current_rb = global_trace.buffer;
+       *current_rb = global_trace.trace_buffer.buffer;
        return trace_buffer_lock_reserve(*current_rb,
                                         type, len, flags, pc);
 }
@@ -1296,7 +1511,7 @@ trace_function(struct trace_array *tr,
               int pc)
 {
        struct ftrace_event_call *call = &event_function;
-       struct ring_buffer *buffer = tr->buffer;
+       struct ring_buffer *buffer = tr->trace_buffer.buffer;
        struct ring_buffer_event *event;
        struct ftrace_entry *entry;
 
@@ -1437,7 +1652,7 @@ void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
                   int pc)
 {
-       __ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
+       __ftrace_trace_stack(tr->trace_buffer.buffer, flags, skip, pc, NULL);
 }
 
 /**
@@ -1453,7 +1668,8 @@ void trace_dump_stack(void)
        local_save_flags(flags);
 
        /* skipping 3 traces, seems to get us at the caller of this function */
-       __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
+       __ftrace_trace_stack(global_trace.trace_buffer.buffer, flags, 3,
+                            preempt_count(), NULL);
 }
 
 static DEFINE_PER_CPU(int, user_stack_count);
@@ -1623,7 +1839,7 @@ void trace_printk_init_buffers(void)
         * directly here. If the global_trace.buffer is already
         * allocated here, then this was called by module code.
         */
-       if (global_trace.buffer)
+       if (global_trace.trace_buffer.buffer)
                tracing_start_cmdline_record();
 }
 
@@ -1683,7 +1899,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
 
        local_save_flags(flags);
        size = sizeof(*entry) + sizeof(u32) * len;
-       buffer = tr->buffer;
+       buffer = tr->trace_buffer.buffer;
        event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
                                          flags, pc);
        if (!event)
@@ -1706,27 +1922,12 @@ out:
 }
 EXPORT_SYMBOL_GPL(trace_vbprintk);
 
-int trace_array_printk(struct trace_array *tr,
-                      unsigned long ip, const char *fmt, ...)
-{
-       int ret;
-       va_list ap;
-
-       if (!(trace_flags & TRACE_ITER_PRINTK))
-               return 0;
-
-       va_start(ap, fmt);
-       ret = trace_array_vprintk(tr, ip, fmt, ap);
-       va_end(ap);
-       return ret;
-}
-
-int trace_array_vprintk(struct trace_array *tr,
-                       unsigned long ip, const char *fmt, va_list args)
+static int
+__trace_array_vprintk(struct ring_buffer *buffer,
+                     unsigned long ip, const char *fmt, va_list args)
 {
        struct ftrace_event_call *call = &event_print;
        struct ring_buffer_event *event;
-       struct ring_buffer *buffer;
        int len = 0, size, pc;
        struct print_entry *entry;
        unsigned long flags;
@@ -1754,7 +1955,6 @@ int trace_array_vprintk(struct trace_array *tr,
 
        local_save_flags(flags);
        size = sizeof(*entry) + len + 1;
-       buffer = tr->buffer;
        event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
                                          flags, pc);
        if (!event)
@@ -1775,6 +1975,42 @@ int trace_array_vprintk(struct trace_array *tr,
        return len;
 }
 
+int trace_array_vprintk(struct trace_array *tr,
+                       unsigned long ip, const char *fmt, va_list args)
+{
+       return __trace_array_vprintk(tr->trace_buffer.buffer, ip, fmt, args);
+}
+
+int trace_array_printk(struct trace_array *tr,
+                      unsigned long ip, const char *fmt, ...)
+{
+       int ret;
+       va_list ap;
+
+       if (!(trace_flags & TRACE_ITER_PRINTK))
+               return 0;
+
+       va_start(ap, fmt);
+       ret = trace_array_vprintk(tr, ip, fmt, ap);
+       va_end(ap);
+       return ret;
+}
+
+int trace_array_printk_buf(struct ring_buffer *buffer,
+                          unsigned long ip, const char *fmt, ...)
+{
+       int ret;
+       va_list ap;
+
+       if (!(trace_flags & TRACE_ITER_PRINTK))
+               return 0;
+
+       va_start(ap, fmt);
+       ret = __trace_array_vprintk(buffer, ip, fmt, ap);
+       va_end(ap);
+       return ret;
+}
+
 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
 {
        return trace_array_vprintk(&global_trace, ip, fmt, args);
@@ -1800,7 +2036,7 @@ peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
        if (buf_iter)
                event = ring_buffer_iter_peek(buf_iter, ts);
        else
-               event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
+               event = ring_buffer_peek(iter->trace_buffer->buffer, cpu, ts,
                                         lost_events);
 
        if (event) {
@@ -1815,7 +2051,7 @@ static struct trace_entry *
 __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
                  unsigned long *missing_events, u64 *ent_ts)
 {
-       struct ring_buffer *buffer = iter->tr->buffer;
+       struct ring_buffer *buffer = iter->trace_buffer->buffer;
        struct trace_entry *ent, *next = NULL;
        unsigned long lost_events = 0, next_lost = 0;
        int cpu_file = iter->cpu_file;
@@ -1892,7 +2128,7 @@ void *trace_find_next_entry_inc(struct trace_iterator *iter)
 
 static void trace_consume(struct trace_iterator *iter)
 {
-       ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
+       ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu, &iter->ts,
                            &iter->lost_events);
 }
 
@@ -1925,13 +2161,12 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
 
 void tracing_iter_reset(struct trace_iterator *iter, int cpu)
 {
-       struct trace_array *tr = iter->tr;
        struct ring_buffer_event *event;
        struct ring_buffer_iter *buf_iter;
        unsigned long entries = 0;
        u64 ts;
 
-       per_cpu_ptr(tr->data, cpu)->skipped_entries = 0;
+       per_cpu_ptr(iter->trace_buffer->data, cpu)->skipped_entries = 0;
 
        buf_iter = trace_buffer_iter(iter, cpu);
        if (!buf_iter)
@@ -1945,13 +2180,13 @@ void tracing_iter_reset(struct trace_iterator *iter, int cpu)
         * by the timestamp being before the start of the buffer.
         */
        while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
-               if (ts >= iter->tr->time_start)
+               if (ts >= iter->trace_buffer->time_start)
                        break;
                entries++;
                ring_buffer_read(buf_iter, NULL);
        }
 
-       per_cpu_ptr(tr->data, cpu)->skipped_entries = entries;
+       per_cpu_ptr(iter->trace_buffer->data, cpu)->skipped_entries = entries;
 }
 
 /*
@@ -1978,8 +2213,10 @@ static void *s_start(struct seq_file *m, loff_t *pos)
                *iter->trace = *tr->current_trace;
        mutex_unlock(&trace_types_lock);
 
+#ifdef CONFIG_TRACER_MAX_TRACE
        if (iter->snapshot && iter->trace->use_max_tr)
                return ERR_PTR(-EBUSY);
+#endif
 
        if (!iter->snapshot)
                atomic_inc(&trace_record_cmdline_disabled);
@@ -2021,17 +2258,21 @@ static void s_stop(struct seq_file *m, void *p)
 {
        struct trace_iterator *iter = m->private;
 
+#ifdef CONFIG_TRACER_MAX_TRACE
        if (iter->snapshot && iter->trace->use_max_tr)
                return;
+#endif
 
        if (!iter->snapshot)
                atomic_dec(&trace_record_cmdline_disabled);
+
        trace_access_unlock(iter->cpu_file);
        trace_event_read_unlock();
 }
 
 static void
-get_total_entries(struct trace_array *tr, unsigned long *total, unsigned long *entries)
+get_total_entries(struct trace_buffer *buf,
+                 unsigned long *total, unsigned long *entries)
 {
        unsigned long count;
        int cpu;
@@ -2040,19 +2281,19 @@ get_total_entries(struct trace_array *tr, unsigned long *total, unsigned long *e
        *entries = 0;
 
        for_each_tracing_cpu(cpu) {
-               count = ring_buffer_entries_cpu(tr->buffer, cpu);
+               count = ring_buffer_entries_cpu(buf->buffer, cpu);
                /*
                 * If this buffer has skipped entries, then we hold all
                 * entries for the trace and we need to ignore the
                 * ones before the time stamp.
                 */
-               if (per_cpu_ptr(tr->data, cpu)->skipped_entries) {
-                       count -= per_cpu_ptr(tr->data, cpu)->skipped_entries;
+               if (per_cpu_ptr(buf->data, cpu)->skipped_entries) {
+                       count -= per_cpu_ptr(buf->data, cpu)->skipped_entries;
                        /* total is the same as the entries */
                        *total += count;
                } else
                        *total += count +
-                               ring_buffer_overrun_cpu(tr->buffer, cpu);
+                               ring_buffer_overrun_cpu(buf->buffer, cpu);
                *entries += count;
        }
 }
@@ -2069,27 +2310,27 @@ static void print_lat_help_header(struct seq_file *m)
        seq_puts(m, "#     \\   /      |||||  \\    |   /           \n");
 }
 
-static void print_event_info(struct trace_array *tr, struct seq_file *m)
+static void print_event_info(struct trace_buffer *buf, struct seq_file *m)
 {
        unsigned long total;
        unsigned long entries;
 
-       get_total_entries(tr, &total, &entries);
+       get_total_entries(buf, &total, &entries);
        seq_printf(m, "# entries-in-buffer/entries-written: %lu/%lu   #P:%d\n",
                   entries, total, num_online_cpus());
        seq_puts(m, "#\n");
 }
 
-static void print_func_help_header(struct trace_array *tr, struct seq_file *m)
+static void print_func_help_header(struct trace_buffer *buf, struct seq_file *m)
 {
-       print_event_info(tr, m);
+       print_event_info(buf, m);
        seq_puts(m, "#           TASK-PID   CPU#      TIMESTAMP  FUNCTION\n");
        seq_puts(m, "#              | |       |          |         |\n");
 }
 
-static void print_func_help_header_irq(struct trace_array *tr, struct seq_file *m)
+static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file *m)
 {
-       print_event_info(tr, m);
+       print_event_info(buf, m);
        seq_puts(m, "#                              _-----=> irqs-off\n");
        seq_puts(m, "#                             / _----=> need-resched\n");
        seq_puts(m, "#                            | / _---=> hardirq/softirq\n");
@@ -2103,8 +2344,8 @@ void
 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
 {
        unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
-       struct trace_array *tr = iter->tr;
-       struct trace_array_cpu *data = per_cpu_ptr(tr->data, tr->cpu);
+       struct trace_buffer *buf = iter->trace_buffer;
+       struct trace_array_cpu *data = per_cpu_ptr(buf->data, buf->cpu);
        struct tracer *type = iter->trace;
        unsigned long entries;
        unsigned long total;
@@ -2112,7 +2353,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
 
        name = type->name;
 
-       get_total_entries(tr, &total, &entries);
+       get_total_entries(buf, &total, &entries);
 
        seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
                   name, UTS_RELEASE);
@@ -2123,7 +2364,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
                   nsecs_to_usecs(data->saved_latency),
                   entries,
                   total,
-                  tr->cpu,
+                  buf->cpu,
 #if defined(CONFIG_PREEMPT_NONE)
                   "server",
 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
@@ -2174,7 +2415,7 @@ static void test_cpu_buff_start(struct trace_iterator *iter)
        if (cpumask_test_cpu(iter->cpu, iter->started))
                return;
 
-       if (per_cpu_ptr(iter->tr->data, iter->cpu)->skipped_entries)
+       if (per_cpu_ptr(iter->trace_buffer->data, iter->cpu)->skipped_entries)
                return;
 
        cpumask_set_cpu(iter->cpu, iter->started);
@@ -2304,7 +2545,7 @@ int trace_empty(struct trace_iterator *iter)
                        if (!ring_buffer_iter_empty(buf_iter))
                                return 0;
                } else {
-                       if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
+                       if (!ring_buffer_empty_cpu(iter->trace_buffer->buffer, cpu))
                                return 0;
                }
                return 1;
@@ -2316,7 +2557,7 @@ int trace_empty(struct trace_iterator *iter)
                        if (!ring_buffer_iter_empty(buf_iter))
                                return 0;
                } else {
-                       if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
+                       if (!ring_buffer_empty_cpu(iter->trace_buffer->buffer, cpu))
                                return 0;
                }
        }
@@ -2340,6 +2581,11 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
                        return ret;
        }
 
+       if (iter->ent->type == TRACE_BPUTS &&
+                       trace_flags & TRACE_ITER_PRINTK &&
+                       trace_flags & TRACE_ITER_PRINTK_MSGONLY)
+               return trace_print_bputs_msg_only(iter);
+
        if (iter->ent->type == TRACE_BPRINT &&
                        trace_flags & TRACE_ITER_PRINTK &&
                        trace_flags & TRACE_ITER_PRINTK_MSGONLY)
@@ -2394,9 +2640,9 @@ void trace_default_header(struct seq_file *m)
        } else {
                if (!(trace_flags & TRACE_ITER_VERBOSE)) {
                        if (trace_flags & TRACE_ITER_IRQ_INFO)
-                               print_func_help_header_irq(iter->tr, m);
+                               print_func_help_header_irq(iter->trace_buffer, m);
                        else
-                               print_func_help_header(iter->tr, m);
+                               print_func_help_header(iter->trace_buffer, m);
                }
        }
 }
@@ -2410,14 +2656,8 @@ static void test_ftrace_alive(struct seq_file *m)
 }
 
 #ifdef CONFIG_TRACER_MAX_TRACE
-static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
+static void show_snapshot_main_help(struct seq_file *m)
 {
-       if (iter->trace->allocated_snapshot)
-               seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
-       else
-               seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
-
-       seq_printf(m, "# Snapshot commands:\n");
        seq_printf(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n");
        seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
        seq_printf(m, "#                      Takes a snapshot of the main buffer.\n");
@@ -2425,6 +2665,35 @@ static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
        seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
        seq_printf(m, "#                       is not a '0' or '1')\n");
 }
+
+static void show_snapshot_percpu_help(struct seq_file *m)
+{
+       seq_printf(m, "# echo 0 > snapshot : Invalid for per_cpu snapshot file.\n");
+#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
+       seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
+       seq_printf(m, "#                      Takes a snapshot of the main buffer for this cpu.\n");
+#else
+       seq_printf(m, "# echo 1 > snapshot : Not supported with this kernel.\n");
+       seq_printf(m, "#                     Must use main snapshot file to allocate.\n");
+#endif
+       seq_printf(m, "# echo 2 > snapshot : Clears this cpu's snapshot buffer (but does not allocate)\n");
+       seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
+       seq_printf(m, "#                       is not a '0' or '1')\n");
+}
+
+static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
+{
+       if (iter->tr->allocated_snapshot)
+               seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
+       else
+               seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
+
+       seq_printf(m, "# Snapshot commands:\n");
+       if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
+               show_snapshot_main_help(m);
+       else
+               show_snapshot_percpu_help(m);
+}
 #else
 /* Should never be called */
 static inline void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter) { }
@@ -2515,11 +2784,15 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
        if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
                goto fail;
 
+       iter->tr = tr;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
        /* Currently only the top directory has a snapshot */
        if (tr->current_trace->print_max || snapshot)
-               iter->tr = &max_tr;
+               iter->trace_buffer = &tr->max_buffer;
        else
-               iter->tr = tr;
+#endif
+               iter->trace_buffer = &tr->trace_buffer;
        iter->snapshot = snapshot;
        iter->pos = -1;
        mutex_init(&iter->mutex);
@@ -2530,7 +2803,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
                iter->trace->open(iter);
 
        /* Annotate start of buffers if we had overruns */
-       if (ring_buffer_overruns(iter->tr->buffer))
+       if (ring_buffer_overruns(iter->trace_buffer->buffer))
                iter->iter_flags |= TRACE_FILE_ANNOTATE;
 
        /* Output in nanoseconds only if we are using a clock in nanoseconds. */
@@ -2544,7 +2817,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
        if (iter->cpu_file == RING_BUFFER_ALL_CPUS) {
                for_each_tracing_cpu(cpu) {
                        iter->buffer_iter[cpu] =
-                               ring_buffer_read_prepare(iter->tr->buffer, cpu);
+                               ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu);
                }
                ring_buffer_read_prepare_sync();
                for_each_tracing_cpu(cpu) {
@@ -2554,12 +2827,14 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
        } else {
                cpu = iter->cpu_file;
                iter->buffer_iter[cpu] =
-                       ring_buffer_read_prepare(iter->tr->buffer, cpu);
+                       ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu);
                ring_buffer_read_prepare_sync();
                ring_buffer_read_start(iter->buffer_iter[cpu]);
                tracing_iter_reset(iter, cpu);
        }
 
+       tr->ref++;
+
        mutex_unlock(&trace_types_lock);
 
        return iter;
@@ -2593,14 +2868,13 @@ static int tracing_release(struct inode *inode, struct file *file)
                return 0;
 
        iter = m->private;
-
-       /* Only the global tracer has a matching max_tr */
-       if (iter->tr == &max_tr)
-               tr = &global_trace;
-       else
-               tr = iter->tr;
+       tr = iter->tr;
 
        mutex_lock(&trace_types_lock);
+
+       WARN_ON(!tr->ref);
+       tr->ref--;
+
        for_each_tracing_cpu(cpu) {
                if (iter->buffer_iter[cpu])
                        ring_buffer_read_finish(iter->buffer_iter[cpu]);
@@ -2634,9 +2908,9 @@ static int tracing_open(struct inode *inode, struct file *file)
                struct trace_array *tr = tc->tr;
 
                if (tc->cpu == RING_BUFFER_ALL_CPUS)
-                       tracing_reset_online_cpus(tr);
+                       tracing_reset_online_cpus(&tr->trace_buffer);
                else
-                       tracing_reset(tr, tc->cpu);
+                       tracing_reset(&tr->trace_buffer, tc->cpu);
        }
 
        if (file->f_mode & FMODE_READ) {
@@ -2805,13 +3079,13 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
                 */
                if (cpumask_test_cpu(cpu, tracing_cpumask) &&
                                !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
-                       atomic_inc(&per_cpu_ptr(tr->data, cpu)->disabled);
-                       ring_buffer_record_disable_cpu(tr->buffer, cpu);
+                       atomic_inc(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled);
+                       ring_buffer_record_disable_cpu(tr->trace_buffer.buffer, cpu);
                }
                if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
                                cpumask_test_cpu(cpu, tracing_cpumask_new)) {
-                       atomic_dec(&per_cpu_ptr(tr->data, cpu)->disabled);
-                       ring_buffer_record_enable_cpu(tr->buffer, cpu);
+                       atomic_dec(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled);
+                       ring_buffer_record_enable_cpu(tr->trace_buffer.buffer, cpu);
                }
        }
        arch_spin_unlock(&ftrace_max_lock);
@@ -2930,9 +3204,9 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
                trace_event_enable_cmd_record(enabled);
 
        if (mask == TRACE_ITER_OVERWRITE) {
-               ring_buffer_change_overwrite(global_trace.buffer, enabled);
+               ring_buffer_change_overwrite(tr->trace_buffer.buffer, enabled);
 #ifdef CONFIG_TRACER_MAX_TRACE
-               ring_buffer_change_overwrite(max_tr.buffer, enabled);
+               ring_buffer_change_overwrite(tr->max_buffer.buffer, enabled);
 #endif
        }
 
@@ -3116,42 +3390,45 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf,
 
 int tracer_init(struct tracer *t, struct trace_array *tr)
 {
-       tracing_reset_online_cpus(tr);
+       tracing_reset_online_cpus(&tr->trace_buffer);
        return t->init(tr);
 }
 
-static void set_buffer_entries(struct trace_array *tr, unsigned long val)
+static void set_buffer_entries(struct trace_buffer *buf, unsigned long val)
 {
        int cpu;
+
        for_each_tracing_cpu(cpu)
-               per_cpu_ptr(tr->data, cpu)->entries = val;
+               per_cpu_ptr(buf->data, cpu)->entries = val;
 }
 
+#ifdef CONFIG_TRACER_MAX_TRACE
 /* resize @tr's buffer to the size of @size_tr's entries */
-static int resize_buffer_duplicate_size(struct trace_array *tr,
-                                       struct trace_array *size_tr, int cpu_id)
+static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
+                                       struct trace_buffer *size_buf, int cpu_id)
 {
        int cpu, ret = 0;
 
        if (cpu_id == RING_BUFFER_ALL_CPUS) {
                for_each_tracing_cpu(cpu) {
-                       ret = ring_buffer_resize(tr->buffer,
-                                per_cpu_ptr(size_tr->data, cpu)->entries, cpu);
+                       ret = ring_buffer_resize(trace_buf->buffer,
+                                per_cpu_ptr(size_buf->data, cpu)->entries, cpu);
                        if (ret < 0)
                                break;
-                       per_cpu_ptr(tr->data, cpu)->entries =
-                               per_cpu_ptr(size_tr->data, cpu)->entries;
+                       per_cpu_ptr(trace_buf->data, cpu)->entries =
+                               per_cpu_ptr(size_buf->data, cpu)->entries;
                }
        } else {
-               ret = ring_buffer_resize(tr->buffer,
-                                per_cpu_ptr(size_tr->data, cpu_id)->entries, cpu_id);
+               ret = ring_buffer_resize(trace_buf->buffer,
+                                per_cpu_ptr(size_buf->data, cpu_id)->entries, cpu_id);
                if (ret == 0)
-                       per_cpu_ptr(tr->data, cpu_id)->entries =
-                               per_cpu_ptr(size_tr->data, cpu_id)->entries;
+                       per_cpu_ptr(trace_buf->data, cpu_id)->entries =
+                               per_cpu_ptr(size_buf->data, cpu_id)->entries;
        }
 
        return ret;
 }
+#endif /* CONFIG_TRACER_MAX_TRACE */
 
 static int __tracing_resize_ring_buffer(struct trace_array *tr,
                                        unsigned long size, int cpu)
@@ -3163,23 +3440,25 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
         * we use the size that was given, and we can forget about
         * expanding it later.
         */
-       ring_buffer_expanded = 1;
+       ring_buffer_expanded = true;
 
        /* May be called before buffers are initialized */
-       if (!tr->buffer)
+       if (!tr->trace_buffer.buffer)
                return 0;
 
-       ret = ring_buffer_resize(tr->buffer, size, cpu);
+       ret = ring_buffer_resize(tr->trace_buffer.buffer, size, cpu);
        if (ret < 0)
                return ret;
 
+#ifdef CONFIG_TRACER_MAX_TRACE
        if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL) ||
            !tr->current_trace->use_max_tr)
                goto out;
 
-       ret = ring_buffer_resize(max_tr.buffer, size, cpu);
+       ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu);
        if (ret < 0) {
-               int r = resize_buffer_duplicate_size(tr, tr, cpu);
+               int r = resize_buffer_duplicate_size(&tr->trace_buffer,
+                                                    &tr->trace_buffer, cpu);
                if (r < 0) {
                        /*
                         * AARGH! We are left with different
@@ -3202,15 +3481,17 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
        }
 
        if (cpu == RING_BUFFER_ALL_CPUS)
-               set_buffer_entries(&max_tr, size);
+               set_buffer_entries(&tr->max_buffer, size);
        else
-               per_cpu_ptr(max_tr.data, cpu)->entries = size;
+               per_cpu_ptr(tr->max_buffer.data, cpu)->entries = size;
 
  out:
+#endif /* CONFIG_TRACER_MAX_TRACE */
+
        if (cpu == RING_BUFFER_ALL_CPUS)
-               set_buffer_entries(tr, size);
+               set_buffer_entries(&tr->trace_buffer, size);
        else
-               per_cpu_ptr(tr->data, cpu)->entries = size;
+               per_cpu_ptr(tr->trace_buffer.data, cpu)->entries = size;
 
        return ret;
 }
@@ -3277,7 +3558,9 @@ static int tracing_set_tracer(const char *buf)
        static struct trace_option_dentry *topts;
        struct trace_array *tr = &global_trace;
        struct tracer *t;
+#ifdef CONFIG_TRACER_MAX_TRACE
        bool had_max_tr;
+#endif
        int ret = 0;
 
        mutex_lock(&trace_types_lock);
@@ -3308,9 +3591,12 @@ static int tracing_set_tracer(const char *buf)
        if (tr->current_trace->reset)
                tr->current_trace->reset(tr);
 
-       had_max_tr = tr->current_trace->allocated_snapshot;
+       /* Current trace needs to be nop_trace before synchronize_sched */
        tr->current_trace = &nop_trace;
 
+#ifdef CONFIG_TRACER_MAX_TRACE
+       had_max_tr = tr->allocated_snapshot;
+
        if (had_max_tr && !t->use_max_tr) {
                /*
                 * We need to make sure that the update_max_tr sees that
@@ -3320,27 +3606,20 @@ static int tracing_set_tracer(const char *buf)
                 * so a synchronized_sched() is sufficient.
                 */
                synchronize_sched();
-               /*
-                * We don't free the ring buffer. instead, resize it because
-                * The max_tr ring buffer has some state (e.g. ring->clock) and
-                * we want preserve it.
-                */
-               ring_buffer_resize(max_tr.buffer, 1, RING_BUFFER_ALL_CPUS);
-               set_buffer_entries(&max_tr, 1);
-               tracing_reset_online_cpus(&max_tr);
-               tr->current_trace->allocated_snapshot = false;
+               free_snapshot(tr);
        }
+#endif
        destroy_trace_option_files(topts);
 
        topts = create_trace_option_files(tr, t);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
        if (t->use_max_tr && !had_max_tr) {
-               /* we need to make per cpu buffer sizes equivalent */
-               ret = resize_buffer_duplicate_size(&max_tr, &global_trace,
-                                                  RING_BUFFER_ALL_CPUS);
+               ret = alloc_snapshot(tr);
                if (ret < 0)
                        goto out;
-               t->allocated_snapshot = true;
        }
+#endif
 
        if (t->init) {
                ret = tracer_init(t, tr);
@@ -3468,6 +3747,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 
        iter->cpu_file = tc->cpu;
        iter->tr = tc->tr;
+       iter->trace_buffer = &tc->tr->trace_buffer;
        mutex_init(&iter->mutex);
        filp->private_data = iter;
 
@@ -3518,7 +3798,7 @@ trace_poll(struct trace_iterator *iter, struct file *filp, poll_table *poll_tabl
                 */
                return POLLIN | POLLRDNORM;
        else
-               return ring_buffer_poll_wait(iter->tr->buffer, iter->cpu_file,
+               return ring_buffer_poll_wait(iter->trace_buffer->buffer, iter->cpu_file,
                                             filp, poll_table);
 }
 
@@ -3857,8 +4137,8 @@ tracing_entries_read(struct file *filp, char __user *ubuf,
                for_each_tracing_cpu(cpu) {
                        /* fill in the size from first enabled cpu */
                        if (size == 0)
-                               size = per_cpu_ptr(tr->data, cpu)->entries;
-                       if (size != per_cpu_ptr(tr->data, cpu)->entries) {
+                               size = per_cpu_ptr(tr->trace_buffer.data, cpu)->entries;
+                       if (size != per_cpu_ptr(tr->trace_buffer.data, cpu)->entries) {
                                buf_size_same = 0;
                                break;
                        }
@@ -3874,7 +4154,7 @@ tracing_entries_read(struct file *filp, char __user *ubuf,
                } else
                        r = sprintf(buf, "X\n");
        } else
-               r = sprintf(buf, "%lu\n", per_cpu_ptr(tr->data, tc->cpu)->entries >> 10);
+               r = sprintf(buf, "%lu\n", per_cpu_ptr(tr->trace_buffer.data, tc->cpu)->entries >> 10);
 
        mutex_unlock(&trace_types_lock);
 
@@ -3921,7 +4201,7 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf,
 
        mutex_lock(&trace_types_lock);
        for_each_tracing_cpu(cpu) {
-               size += per_cpu_ptr(tr->data, cpu)->entries >> 10;
+               size += per_cpu_ptr(tr->trace_buffer.data, cpu)->entries >> 10;
                if (!ring_buffer_expanded)
                        expanded_size += trace_buf_size >> 10;
        }
@@ -4026,7 +4306,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 
        local_save_flags(irq_flags);
        size = sizeof(*entry) + cnt + 2; /* possible \n added */
-       buffer = global_trace.buffer;
+       buffer = global_trace.trace_buffer.buffer;
        event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
                                          irq_flags, preempt_count());
        if (!event) {
@@ -4111,16 +4391,19 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
 
        tr->clock_id = i;
 
-       ring_buffer_set_clock(tr->buffer, trace_clocks[i].func);
-       if (tr->flags & TRACE_ARRAY_FL_GLOBAL && max_tr.buffer)
-               ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
+       ring_buffer_set_clock(tr->trace_buffer.buffer, trace_clocks[i].func);
 
        /*
         * New clock may not be consistent with the previous clock.
         * Reset the buffer so that it doesn't have incomparable timestamps.
         */
-       tracing_reset_online_cpus(&global_trace);
-       tracing_reset_online_cpus(&max_tr);
+       tracing_reset_online_cpus(&global_trace.trace_buffer);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+       if (tr->flags & TRACE_ARRAY_FL_GLOBAL && tr->max_buffer.buffer)
+               ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func);
+       tracing_reset_online_cpus(&global_trace.max_buffer);
+#endif
 
        mutex_unlock(&trace_types_lock);
 
@@ -4137,6 +4420,12 @@ static int tracing_clock_open(struct inode *inode, struct file *file)
        return single_open(file, tracing_clock_show, inode->i_private);
 }
 
+struct ftrace_buffer_info {
+       struct trace_iterator   iter;
+       void                    *spare;
+       unsigned int            read;
+};
+
 #ifdef CONFIG_TRACER_SNAPSHOT
 static int tracing_snapshot_open(struct inode *inode, struct file *file)
 {
@@ -4160,6 +4449,8 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
                        return -ENOMEM;
                }
                iter->tr = tc->tr;
+               iter->trace_buffer = &tc->tr->max_buffer;
+               iter->cpu_file = tc->cpu;
                m->private = iter;
                file->private_data = m;
        }
@@ -4194,33 +4485,41 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
 
        switch (val) {
        case 0:
-               if (tr->current_trace->allocated_snapshot) {
-                       /* free spare buffer */
-                       ring_buffer_resize(max_tr.buffer, 1,
-                                          RING_BUFFER_ALL_CPUS);
-                       set_buffer_entries(&max_tr, 1);
-                       tracing_reset_online_cpus(&max_tr);
-                       tr->current_trace->allocated_snapshot = false;
+               if (iter->cpu_file != RING_BUFFER_ALL_CPUS) {
+                       ret = -EINVAL;
+                       break;
                }
+               if (tr->allocated_snapshot)
+                       free_snapshot(tr);
                break;
        case 1:
-               if (!tr->current_trace->allocated_snapshot) {
-                       /* allocate spare buffer */
-                       ret = resize_buffer_duplicate_size(&max_tr,
-                                       &global_trace, RING_BUFFER_ALL_CPUS);
+/* Only allow per-cpu swap if the ring buffer supports it */
+#ifndef CONFIG_RING_BUFFER_ALLOW_SWAP
+               if (iter->cpu_file != RING_BUFFER_ALL_CPUS) {
+                       ret = -EINVAL;
+                       break;
+               }
+#endif
+               if (!tr->allocated_snapshot) {
+                       ret = alloc_snapshot(tr);
                        if (ret < 0)
                                break;
-                       tr->current_trace->allocated_snapshot = true;
                }
-
                local_irq_disable();
                /* Now, we're going to swap */
-               update_max_tr(&global_trace, current, smp_processor_id());
+               if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
+                       update_max_tr(tr, current, smp_processor_id());
+               else
+                       update_max_tr_single(tr, current, iter->cpu_file);
                local_irq_enable();
                break;
        default:
-               if (tr->current_trace->allocated_snapshot)
-                       tracing_reset_online_cpus(&max_tr);
+               if (tr->allocated_snapshot) {
+                       if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
+                               tracing_reset_online_cpus(&tr->max_buffer);
+                       else
+                               tracing_reset(&tr->max_buffer, iter->cpu_file);
+               }
                break;
        }
 
@@ -4248,6 +4547,35 @@ static int tracing_snapshot_release(struct inode *inode, struct file *file)
        return 0;
 }
 
+static int tracing_buffers_open(struct inode *inode, struct file *filp);
+static ssize_t tracing_buffers_read(struct file *filp, char __user *ubuf,
+                                   size_t count, loff_t *ppos);
+static int tracing_buffers_release(struct inode *inode, struct file *file);
+static ssize_t tracing_buffers_splice_read(struct file *file, loff_t *ppos,
+                  struct pipe_inode_info *pipe, size_t len, unsigned int flags);
+
+static int snapshot_raw_open(struct inode *inode, struct file *filp)
+{
+       struct ftrace_buffer_info *info;
+       int ret;
+
+       ret = tracing_buffers_open(inode, filp);
+       if (ret < 0)
+               return ret;
+
+       info = filp->private_data;
+
+       if (info->iter.trace->use_max_tr) {
+               tracing_buffers_release(inode, filp);
+               return -EBUSY;
+       }
+
+       info->iter.snapshot = true;
+       info->iter.trace_buffer = &info->iter.tr->max_buffer;
+
+       return ret;
+}
+
 #endif /* CONFIG_TRACER_SNAPSHOT */
 
 
@@ -4314,14 +4642,17 @@ static const struct file_operations snapshot_fops = {
        .llseek         = tracing_seek,
        .release        = tracing_snapshot_release,
 };
-#endif /* CONFIG_TRACER_SNAPSHOT */
 
-struct ftrace_buffer_info {
-       struct trace_iterator   iter;
-       void                    *spare;
-       unsigned int            read;
+static const struct file_operations snapshot_raw_fops = {
+       .open           = snapshot_raw_open,
+       .read           = tracing_buffers_read,
+       .release        = tracing_buffers_release,
+       .splice_read    = tracing_buffers_splice_read,
+       .llseek         = no_llseek,
 };
 
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
 static int tracing_buffers_open(struct inode *inode, struct file *filp)
 {
        struct trace_cpu *tc = inode->i_private;
@@ -4335,15 +4666,22 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
        if (!info)
                return -ENOMEM;
 
+       mutex_lock(&trace_types_lock);
+
+       tr->ref++;
+
        info->iter.tr           = tr;
        info->iter.cpu_file     = tc->cpu;
        info->iter.trace        = tr->current_trace;
+       info->iter.trace_buffer = &tr->trace_buffer;
        info->spare             = NULL;
        /* Force reading ring buffer for first read */
        info->read              = (unsigned int)-1;
 
        filp->private_data = info;
 
+       mutex_unlock(&trace_types_lock);
+
        return nonseekable_open(inode, filp);
 }
 
@@ -4363,15 +4701,26 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
        struct ftrace_buffer_info *info = filp->private_data;
        struct trace_iterator *iter = &info->iter;
        ssize_t ret;
-       size_t size;
+       ssize_t size;
 
        if (!count)
                return 0;
 
+       mutex_lock(&trace_types_lock);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+       if (iter->snapshot && iter->tr->current_trace->use_max_tr) {
+               size = -EBUSY;
+               goto out_unlock;
+       }
+#endif
+
        if (!info->spare)
-               info->spare = ring_buffer_alloc_read_page(iter->tr->buffer, iter->cpu_file);
+               info->spare = ring_buffer_alloc_read_page(iter->trace_buffer->buffer,
+                                                         iter->cpu_file);
+       size = -ENOMEM;
        if (!info->spare)
-               return -ENOMEM;
+               goto out_unlock;
 
        /* Do we have previous read data to read? */
        if (info->read < PAGE_SIZE)
@@ -4379,7 +4728,7 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 
  again:
        trace_access_lock(iter->cpu_file);
-       ret = ring_buffer_read_page(iter->tr->buffer,
+       ret = ring_buffer_read_page(iter->trace_buffer->buffer,
                                    &info->spare,
                                    count,
                                    iter->cpu_file, 0);
@@ -4387,31 +4736,42 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 
        if (ret < 0) {
                if (trace_empty(iter)) {
-                       if ((filp->f_flags & O_NONBLOCK))
-                               return -EAGAIN;
+                       if ((filp->f_flags & O_NONBLOCK)) {
+                               size = -EAGAIN;
+                               goto out_unlock;
+                       }
+                       mutex_unlock(&trace_types_lock);
                        iter->trace->wait_pipe(iter);
-                       if (signal_pending(current))
-                               return -EINTR;
+                       mutex_lock(&trace_types_lock);
+                       if (signal_pending(current)) {
+                               size = -EINTR;
+                               goto out_unlock;
+                       }
                        goto again;
                }
-               return 0;
+               size = 0;
+               goto out_unlock;
        }
 
        info->read = 0;
-
  read:
        size = PAGE_SIZE - info->read;
        if (size > count)
                size = count;
 
        ret = copy_to_user(ubuf, info->spare + info->read, size);
-       if (ret == size)
-               return -EFAULT;
+       if (ret == size) {
+               size = -EFAULT;
+               goto out_unlock;
+       }
        size -= ret;
 
        *ppos += size;
        info->read += size;
 
+ out_unlock:
+       mutex_unlock(&trace_types_lock);
+
        return size;
 }
 
@@ -4420,10 +4780,17 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
        struct ftrace_buffer_info *info = file->private_data;
        struct trace_iterator *iter = &info->iter;
 
+       mutex_lock(&trace_types_lock);
+
+       WARN_ON(!iter->tr->ref);
+       iter->tr->ref--;
+
        if (info->spare)
-               ring_buffer_free_read_page(iter->tr->buffer, info->spare);
+               ring_buffer_free_read_page(iter->trace_buffer->buffer, info->spare);
        kfree(info);
 
+       mutex_unlock(&trace_types_lock);
+
        return 0;
 }
 
@@ -4501,10 +4868,21 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
        };
        struct buffer_ref *ref;
        int entries, size, i;
-       size_t ret;
+       ssize_t ret;
 
-       if (splice_grow_spd(pipe, &spd))
-               return -ENOMEM;
+       mutex_lock(&trace_types_lock);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+       if (iter->snapshot && iter->tr->current_trace->use_max_tr) {
+               ret = -EBUSY;
+               goto out;
+       }
+#endif
+
+       if (splice_grow_spd(pipe, &spd)) {
+               ret = -ENOMEM;
+               goto out;
+       }
 
        if (*ppos & (PAGE_SIZE - 1)) {
                ret = -EINVAL;
@@ -4521,7 +4899,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 
  again:
        trace_access_lock(iter->cpu_file);
-       entries = ring_buffer_entries_cpu(iter->tr->buffer, iter->cpu_file);
+       entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
 
        for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
                struct page *page;
@@ -4532,7 +4910,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                        break;
 
                ref->ref = 1;
-               ref->buffer = iter->tr->buffer;
+               ref->buffer = iter->trace_buffer->buffer;
                ref->page = ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file);
                if (!ref->page) {
                        kfree(ref);
@@ -4564,7 +4942,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                spd.nr_pages++;
                *ppos += PAGE_SIZE;
 
-               entries = ring_buffer_entries_cpu(iter->tr->buffer, iter->cpu_file);
+               entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
        }
 
        trace_access_unlock(iter->cpu_file);
@@ -4576,7 +4954,9 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                        ret = -EAGAIN;
                        goto out;
                }
+               mutex_unlock(&trace_types_lock);
                iter->trace->wait_pipe(iter);
+               mutex_lock(&trace_types_lock);
                if (signal_pending(current)) {
                        ret = -EINTR;
                        goto out;
@@ -4587,6 +4967,8 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
        ret = splice_to_pipe(pipe, &spd);
        splice_shrink_spd(&spd);
 out:
+       mutex_unlock(&trace_types_lock);
+
        return ret;
 }
 
@@ -4605,6 +4987,7 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 {
        struct trace_cpu *tc = filp->private_data;
        struct trace_array *tr = tc->tr;
+       struct trace_buffer *trace_buf = &tr->trace_buffer;
        struct trace_seq *s;
        unsigned long cnt;
        unsigned long long t;
@@ -4617,41 +5000,41 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 
        trace_seq_init(s);
 
-       cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
+       cnt = ring_buffer_entries_cpu(trace_buf->buffer, cpu);
        trace_seq_printf(s, "entries: %ld\n", cnt);
 
-       cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
+       cnt = ring_buffer_overrun_cpu(trace_buf->buffer, cpu);
        trace_seq_printf(s, "overrun: %ld\n", cnt);
 
-       cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
+       cnt = ring_buffer_commit_overrun_cpu(trace_buf->buffer, cpu);
        trace_seq_printf(s, "commit overrun: %ld\n", cnt);
 
-       cnt = ring_buffer_bytes_cpu(tr->buffer, cpu);
+       cnt = ring_buffer_bytes_cpu(trace_buf->buffer, cpu);
        trace_seq_printf(s, "bytes: %ld\n", cnt);
 
        if (trace_clocks[trace_clock_id].in_ns) {
                /* local or global for trace_clock */
-               t = ns2usecs(ring_buffer_oldest_event_ts(tr->buffer, cpu));
+               t = ns2usecs(ring_buffer_oldest_event_ts(trace_buf->buffer, cpu));
                usec_rem = do_div(t, USEC_PER_SEC);
                trace_seq_printf(s, "oldest event ts: %5llu.%06lu\n",
                                                                t, usec_rem);
 
-               t = ns2usecs(ring_buffer_time_stamp(tr->buffer, cpu));
+               t = ns2usecs(ring_buffer_time_stamp(trace_buf->buffer, cpu));
                usec_rem = do_div(t, USEC_PER_SEC);
                trace_seq_printf(s, "now ts: %5llu.%06lu\n", t, usec_rem);
        } else {
                /* counter or tsc mode for trace_clock */
                trace_seq_printf(s, "oldest event ts: %llu\n",
-                               ring_buffer_oldest_event_ts(tr->buffer, cpu));
+                               ring_buffer_oldest_event_ts(trace_buf->buffer, cpu));
 
                trace_seq_printf(s, "now ts: %llu\n",
-                               ring_buffer_time_stamp(tr->buffer, cpu));
+                               ring_buffer_time_stamp(trace_buf->buffer, cpu));
        }
 
-       cnt = ring_buffer_dropped_events_cpu(tr->buffer, cpu);
+       cnt = ring_buffer_dropped_events_cpu(trace_buf->buffer, cpu);
        trace_seq_printf(s, "dropped events: %ld\n", cnt);
 
-       cnt = ring_buffer_read_events_cpu(tr->buffer, cpu);
+       cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
        trace_seq_printf(s, "read events: %ld\n", cnt);
 
        count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
@@ -4754,7 +5137,7 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu)
 static void
 tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
 {
-       struct trace_array_cpu *data = per_cpu_ptr(tr->data, cpu);
+       struct trace_array_cpu *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
        struct dentry *d_percpu = tracing_dentry_percpu(tr, cpu);
        struct dentry *d_cpu;
        char cpu_dir[30]; /* 30 characters should be more than enough */
@@ -4785,6 +5168,14 @@ tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
 
        trace_create_file("buffer_size_kb", 0444, d_cpu,
                        (void *)&data->trace_cpu, &tracing_entries_fops);
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+       trace_create_file("snapshot", 0644, d_cpu,
+                         (void *)&data->trace_cpu, &snapshot_fops);
+
+       trace_create_file("snapshot_raw", 0444, d_cpu,
+                       (void *)&data->trace_cpu, &snapshot_raw_fops);
+#endif
 }
 
 #ifdef CONFIG_FTRACE_SELFTEST
@@ -5038,7 +5429,7 @@ rb_simple_read(struct file *filp, char __user *ubuf,
               size_t cnt, loff_t *ppos)
 {
        struct trace_array *tr = filp->private_data;
-       struct ring_buffer *buffer = tr->buffer;
+       struct ring_buffer *buffer = tr->trace_buffer.buffer;
        char buf[64];
        int r;
 
@@ -5057,7 +5448,7 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
                size_t cnt, loff_t *ppos)
 {
        struct trace_array *tr = filp->private_data;
-       struct ring_buffer *buffer = tr->buffer;
+       struct ring_buffer *buffer = tr->trace_buffer.buffer;
        unsigned long val;
        int ret;
 
@@ -5096,12 +5487,74 @@ struct dentry *trace_instance_dir;
 static void
 init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer);
 
-static int new_instance_create(const char *name)
+static void init_trace_buffers(struct trace_array *tr, struct trace_buffer *buf)
+{
+       int cpu;
+
+       for_each_tracing_cpu(cpu) {
+               memset(per_cpu_ptr(buf->data, cpu), 0, sizeof(struct trace_array_cpu));
+               per_cpu_ptr(buf->data, cpu)->trace_cpu.cpu = cpu;
+               per_cpu_ptr(buf->data, cpu)->trace_cpu.tr = tr;
+       }
+}
+
+static int
+allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size)
 {
        enum ring_buffer_flags rb_flags;
+
+       rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
+
+       buf->buffer = ring_buffer_alloc(size, rb_flags);
+       if (!buf->buffer)
+               return -ENOMEM;
+
+       buf->data = alloc_percpu(struct trace_array_cpu);
+       if (!buf->data) {
+               ring_buffer_free(buf->buffer);
+               return -ENOMEM;
+       }
+
+       init_trace_buffers(tr, buf);
+
+       /* Allocate the first page for all buffers */
+       set_buffer_entries(&tr->trace_buffer,
+                          ring_buffer_size(tr->trace_buffer.buffer, 0));
+
+       return 0;
+}
+
+static int allocate_trace_buffers(struct trace_array *tr, int size)
+{
+       int ret;
+
+       ret = allocate_trace_buffer(tr, &tr->trace_buffer, size);
+       if (ret)
+               return ret;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+       ret = allocate_trace_buffer(tr, &tr->max_buffer,
+                                   allocate_snapshot ? size : 1);
+       if (WARN_ON(ret)) {
+               ring_buffer_free(tr->trace_buffer.buffer);
+               free_percpu(tr->trace_buffer.data);
+               return -ENOMEM;
+       }
+       tr->allocated_snapshot = allocate_snapshot;
+
+       /*
+        * Only the top level trace array gets its snapshot allocated
+        * from the kernel command line.
+        */
+       allocate_snapshot = false;
+#endif
+       return 0;
+}
+
+static int new_instance_create(const char *name)
+{
        struct trace_array *tr;
        int ret;
-       int i;
 
        mutex_lock(&trace_types_lock);
 
@@ -5127,22 +5580,9 @@ static int new_instance_create(const char *name)
        INIT_LIST_HEAD(&tr->systems);
        INIT_LIST_HEAD(&tr->events);
 
-       rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
-
-       tr->buffer = ring_buffer_alloc(trace_buf_size, rb_flags);
-       if (!tr->buffer)
-               goto out_free_tr;
-
-       tr->data = alloc_percpu(struct trace_array_cpu);
-       if (!tr->data)
+       if (allocate_trace_buffers(tr, trace_buf_size) < 0)
                goto out_free_tr;
 
-       for_each_tracing_cpu(i) {
-               memset(per_cpu_ptr(tr->data, i), 0, sizeof(struct trace_array_cpu));
-               per_cpu_ptr(tr->data, i)->trace_cpu.cpu = i;
-               per_cpu_ptr(tr->data, i)->trace_cpu.tr = tr;
-       }
-
        /* Holder for file callbacks */
        tr->trace_cpu.cpu = RING_BUFFER_ALL_CPUS;
        tr->trace_cpu.tr = tr;
@@ -5164,8 +5604,8 @@ static int new_instance_create(const char *name)
        return 0;
 
  out_free_tr:
-       if (tr->buffer)
-               ring_buffer_free(tr->buffer);
+       if (tr->trace_buffer.buffer)
+               ring_buffer_free(tr->trace_buffer.buffer);
        kfree(tr->name);
        kfree(tr);
 
@@ -5194,12 +5634,16 @@ static int instance_delete(const char *name)
        if (!found)
                goto out_unlock;
 
+       ret = -EBUSY;
+       if (tr->ref)
+               goto out_unlock;
+
        list_del(&tr->list);
 
        event_trace_del_tracer(tr);
        debugfs_remove_recursive(tr->dir);
-       free_percpu(tr->data);
-       ring_buffer_free(tr->buffer);
+       free_percpu(tr->trace_buffer.data);
+       ring_buffer_free(tr->trace_buffer.buffer);
 
        kfree(tr->name);
        kfree(tr);
@@ -5289,6 +5733,7 @@ static __init void create_trace_instances(struct dentry *d_tracer)
 static void
 init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
 {
+       int cpu;
 
        trace_create_file("trace_options", 0644, d_tracer,
                          tr, &tracing_iter_fops);
@@ -5316,12 +5761,20 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
 
        trace_create_file("tracing_on", 0644, d_tracer,
                            tr, &rb_simple_fops);
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+       trace_create_file("snapshot", 0644, d_tracer,
+                         (void *)&tr->trace_cpu, &snapshot_fops);
+#endif
+
+       for_each_tracing_cpu(cpu)
+               tracing_init_debugfs_percpu(tr, cpu);
+
 }
 
 static __init int tracer_init_debugfs(void)
 {
        struct dentry *d_tracer;
-       int cpu;
 
        trace_access_lock_init();
 
@@ -5357,18 +5810,10 @@ static __init int tracer_init_debugfs(void)
                        &ftrace_update_tot_cnt, &tracing_dyn_info_fops);
 #endif
 
-#ifdef CONFIG_TRACER_SNAPSHOT
-       trace_create_file("snapshot", 0644, d_tracer,
-                         (void *)&global_trace.trace_cpu, &snapshot_fops);
-#endif
-
        create_trace_instances(d_tracer);
 
        create_trace_options_dir(&global_trace);
 
-       for_each_tracing_cpu(cpu)
-               tracing_init_debugfs_percpu(&global_trace, cpu);
-
        return 0;
 }
 
@@ -5439,6 +5884,7 @@ void trace_init_global_iter(struct trace_iterator *iter)
        iter->tr = &global_trace;
        iter->trace = iter->tr->current_trace;
        iter->cpu_file = RING_BUFFER_ALL_CPUS;
+       iter->trace_buffer = &global_trace.trace_buffer;
 }
 
 static void
@@ -5476,7 +5922,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
        trace_init_global_iter(&iter);
 
        for_each_tracing_cpu(cpu) {
-               atomic_inc(&per_cpu_ptr(iter.tr->data, cpu)->disabled);
+               atomic_inc(&per_cpu_ptr(iter.tr->trace_buffer.data, cpu)->disabled);
        }
 
        old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
@@ -5544,7 +5990,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
                trace_flags |= old_userobj;
 
                for_each_tracing_cpu(cpu) {
-                       atomic_dec(&per_cpu_ptr(iter.tr->data, cpu)->disabled);
+                       atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
                }
                tracing_on();
        }
@@ -5564,8 +6010,6 @@ EXPORT_SYMBOL_GPL(ftrace_dump);
 __init static int tracer_alloc_buffers(void)
 {
        int ring_buf_size;
-       enum ring_buffer_flags rb_flags;
-       int i;
        int ret = -ENOMEM;
 
 
@@ -5586,68 +6030,21 @@ __init static int tracer_alloc_buffers(void)
        else
                ring_buf_size = 1;
 
-       rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
-
        cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
        cpumask_copy(tracing_cpumask, cpu_all_mask);
 
        raw_spin_lock_init(&global_trace.start_lock);
 
        /* TODO: make the number of buffers hot pluggable with CPUS */
-       global_trace.buffer = ring_buffer_alloc(ring_buf_size, rb_flags);
-       if (!global_trace.buffer) {
+       if (allocate_trace_buffers(&global_trace, ring_buf_size) < 0) {
                printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
                WARN_ON(1);
                goto out_free_cpumask;
        }
 
-       global_trace.data = alloc_percpu(struct trace_array_cpu);
-
-       if (!global_trace.data) {
-               printk(KERN_ERR "tracer: failed to allocate percpu memory!\n");
-               WARN_ON(1);
-               goto out_free_cpumask;
-       }
-
-       for_each_tracing_cpu(i) {
-               memset(per_cpu_ptr(global_trace.data, i), 0, sizeof(struct trace_array_cpu));
-               per_cpu_ptr(global_trace.data, i)->trace_cpu.cpu = i;
-               per_cpu_ptr(global_trace.data, i)->trace_cpu.tr = &global_trace;
-       }
-
        if (global_trace.buffer_disabled)
                tracing_off();
 
-#ifdef CONFIG_TRACER_MAX_TRACE
-       max_tr.data = alloc_percpu(struct trace_array_cpu);
-       if (!max_tr.data) {
-               printk(KERN_ERR "tracer: failed to allocate percpu memory!\n");
-               WARN_ON(1);
-               goto out_free_cpumask;
-       }
-       max_tr.buffer = ring_buffer_alloc(1, rb_flags);
-       raw_spin_lock_init(&max_tr.start_lock);
-       if (!max_tr.buffer) {
-               printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
-               WARN_ON(1);
-               ring_buffer_free(global_trace.buffer);
-               goto out_free_cpumask;
-       }
-
-       for_each_tracing_cpu(i) {
-               memset(per_cpu_ptr(max_tr.data, i), 0, sizeof(struct trace_array_cpu));
-               per_cpu_ptr(max_tr.data, i)->trace_cpu.cpu = i;
-               per_cpu_ptr(max_tr.data, i)->trace_cpu.tr = &max_tr;
-       }
-#endif
-
-       /* Allocate the first page for all buffers */
-       set_buffer_entries(&global_trace,
-                          ring_buffer_size(global_trace.buffer, 0));
-#ifdef CONFIG_TRACER_MAX_TRACE
-       set_buffer_entries(&max_tr, 1);
-#endif
-
        trace_init_cmdlines();
 
        register_tracer(&nop_trace);
@@ -5682,8 +6079,10 @@ __init static int tracer_alloc_buffers(void)
        return 0;
 
 out_free_cpumask:
-       free_percpu(global_trace.data);
-       free_percpu(max_tr.data);
+       free_percpu(global_trace.trace_buffer.data);
+#ifdef CONFIG_TRACER_MAX_TRACE
+       free_percpu(global_trace.max_buffer.data);
+#endif
        free_cpumask_var(tracing_cpumask);
 out_free_buffer_mask:
        free_cpumask_var(tracing_buffer_mask);