[ 038/104] tracing: Use stack of calling function for stack tracer

Greg Kroah-Hartman
2013-05-06T23:30:54Z

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

commit 87889501d0adfae10e3b0f0e6f2d7536eed9ae84 upstream.

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.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/trace/trace_stack.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- 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, unsig
if (per_cpu(trace_active, cpu)++ != 0)
goto out;

- check_stack();
+ check_stack(&stack);

out:
per_cpu(trace_active, cpu)--;