tracing: Use stack of calling function for stack tracer

Use the stack of stack_trace_call() instead of check_stack() as
the test pointer for max stack size. It makes it a bit cleaner
and a little more accurate.

Adding stable, as a later fix depends on this patch.

Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 42ca822fc7019670d8bea7291caea4110477749b..dc02e29d8255e4cddd5aaff7274c67a5143d40cf 100644 (file)
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -39,20 +39,21 @@ static DEFINE_MUTEX(stack_sysctl_mutex);
 int stack_tracer_enabled;
 static int last_stack_tracer_enabled;
 
-static inline void check_stack(void)
+static inline void
+check_stack(unsigned long *stack)
 {
        unsigned long this_size, flags;
        unsigned long *p, *top, *start;
        int i;
 
-       this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
+       this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
        this_size = THREAD_SIZE - this_size;
 
        if (this_size <= max_stack_size)
                return;
 
        /* we do not handle interrupt stacks yet */
-       if (!object_is_on_stack(&this_size))
+       if (!object_is_on_stack(stack))
                return;
 
        local_irq_save(flags);
@@ -73,7 +74,7 @@ static inline void check_stack(void)
         * Now find where in the stack these are.
         */
        i = 0;
-       start = &this_size;
+       start = stack;
        top = (unsigned long *)
                (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
 
@@ -113,6 +114,7 @@ static void
 stack_trace_call(unsigned long ip, unsigned long parent_ip,
                 struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
+       unsigned long stack;
        int cpu;
 
        preempt_disable_notrace();
@@ -122,7 +124,7 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip,
        if (per_cpu(trace_active, cpu)++ != 0)
                goto out;
 
-       check_stack();
+       check_stack(&stack);
 
  out:
        per_cpu(trace_active, cpu)--;