/* Current function tracing op */
struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
+/* What to set function_trace_op to */
+static struct ftrace_ops *set_function_trace_op;
/* List for set_ftrace_pid's pids. */
LIST_HEAD(ftrace_pids);
global_ops.func = func;
}
+static void ftrace_sync(struct work_struct *work)
+{
+ /*
+ * This function is just a stub to implement a hard force
+ * of synchronize_sched(). This requires synchronizing
+ * tasks even in userspace and idle.
+ *
+ * Yes, function tracing is rude.
+ */
+}
+
+static void ftrace_sync_ipi(void *data)
+{
+ /* Probably not needed, but do it anyway */
+ smp_rmb();
+}
+
static void update_ftrace_function(void)
{
ftrace_func_t func;
!FTRACE_FORCE_LIST_FUNC)) {
/* Set the ftrace_ops that the arch callback uses */
if (ftrace_ops_list == &global_ops)
- function_trace_op = ftrace_global_list;
+ set_function_trace_op = ftrace_global_list;
else
- function_trace_op = ftrace_ops_list;
+ set_function_trace_op = ftrace_ops_list;
func = ftrace_ops_list->func;
} else {
/* Just use the default ftrace_ops */
- function_trace_op = &ftrace_list_end;
+ set_function_trace_op = &ftrace_list_end;
func = ftrace_ops_list_func;
}
+ /* If there's no change, then do nothing more here */
+ if (ftrace_trace_function == func)
+ return;
+
+ /*
+ * If we are using the list function, it doesn't care
+ * about the function_trace_ops.
+ */
+ if (func == ftrace_ops_list_func) {
+ ftrace_trace_function = func;
+ /*
+ * Don't even bother setting function_trace_ops,
+ * it would be racy to do so anyway.
+ */
+ return;
+ }
+
+#ifndef CONFIG_DYNAMIC_FTRACE
+ /*
+ * For static tracing, we need to be a bit more careful.
+ * The function change takes affect immediately. Thus,
+ * we need to coorditate the setting of the function_trace_ops
+ * with the setting of the ftrace_trace_function.
+ *
+ * Set the function to the list ops, which will call the
+ * function we want, albeit indirectly, but it handles the
+ * ftrace_ops and doesn't depend on function_trace_op.
+ */
+ ftrace_trace_function = ftrace_ops_list_func;
+ /*
+ * Make sure all CPUs see this. Yes this is slow, but static
+ * tracing is slow and nasty to have enabled.
+ */
+ schedule_on_each_cpu(ftrace_sync);
+ /* Now all cpus are using the list ops. */
+ function_trace_op = set_function_trace_op;
+ /* Make sure the function_trace_op is visible on all CPUs */
+ smp_wmb();
+ /* Nasty way to force a rmb on all cpus */
+ smp_call_function(ftrace_sync_ipi, NULL, 1);
+ /* OK, we are all set to update the ftrace_trace_function now! */
+#endif /* !CONFIG_DYNAMIC_FTRACE */
+
ftrace_trace_function = func;
}
return 0;
}
-static void ftrace_sync(struct work_struct *work)
-{
- /*
- * This function is just a stub to implement a hard force
- * of synchronize_sched(). This requires synchronizing
- * tasks even in userspace and idle.
- *
- * Yes, function tracing is rude.
- */
-}
-
static int __unregister_ftrace_function(struct ftrace_ops *ops)
{
int ret;
static struct pid * const ftrace_swapper_pid = &init_struct_pid;
-loff_t
-ftrace_filter_lseek(struct file *file, loff_t offset, int whence)
-{
- loff_t ret;
-
- if (file->f_mode & FMODE_READ)
- ret = seq_lseek(file, offset, whence);
- else
- file->f_pos = ret = 1;
-
- return ret;
-}
-
#ifdef CONFIG_DYNAMIC_FTRACE
#ifndef CONFIG_FTRACE_MCOUNT_RECORD
else if (command & FTRACE_DISABLE_CALLS)
ftrace_replace_code(0);
- if (update && ftrace_trace_function != ftrace_ops_list_func)
+ if (update && ftrace_trace_function != ftrace_ops_list_func) {
+ function_trace_op = set_function_trace_op;
+ smp_wmb();
+ /* If irqs are disabled, we are in stop machine */
+ if (!irqs_disabled())
+ smp_call_function(ftrace_sync_ipi, NULL, 1);
ftrace_update_ftrace_func(ftrace_trace_function);
+ }
if (command & FTRACE_START_FUNC_RET)
ftrace_enable_ftrace_graph_caller();
* routine, you can use ftrace_filter_write() for the write
* routine if @flag has FTRACE_ITER_FILTER set, or
* ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set.
- * ftrace_filter_lseek() should be used as the lseek routine, and
+ * tracing_lseek() should be used as the lseek routine, and
* release must call ftrace_regex_release().
*/
int
.open = ftrace_filter_open,
.read = seq_read,
.write = ftrace_filter_write,
- .llseek = ftrace_filter_lseek,
+ .llseek = tracing_lseek,
.release = ftrace_regex_release,
};
.open = ftrace_notrace_open,
.read = seq_read,
.write = ftrace_notrace_write,
- .llseek = ftrace_filter_lseek,
+ .llseek = tracing_lseek,
.release = ftrace_regex_release,
};
.open = ftrace_graph_open,
.read = seq_read,
.write = ftrace_graph_write,
- .llseek = ftrace_filter_lseek,
+ .llseek = tracing_lseek,
.release = ftrace_graph_release,
};
.open = ftrace_graph_notrace_open,
.read = seq_read,
.write = ftrace_graph_write,
- .llseek = ftrace_filter_lseek,
+ .llseek = tracing_lseek,
.release = ftrace_graph_release,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
.open = ftrace_pid_open,
.write = ftrace_pid_write,
.read = seq_read,
- .llseek = ftrace_filter_lseek,
+ .llseek = tracing_lseek,
.release = ftrace_pid_release,
};