ftrace: stacktrace fix

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

4 files changed, 13 insertions, 3 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 0d3714e7110b..017ab44d572a 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -120,4 +120,12 @@ static inline void tracer_disable(void)
 # define trace_preempt_off(a0, a1)              do { } while (0)
 #endif
 
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+extern void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
+#else
+static inline void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
+#endif
+
 #endif /* _LINUX_FTRACE_H */
diff --git a/kernel/semaphore.c b/kernel/semaphore.c
index 5c2942e768cd..1a064adab658 100644
--- a/kernel/semaphore.c
+++ b/kernel/semaphore.c
@@ -31,6 +31,7 @@
 #include <linux/sched.h>
 #include <linux/semaphore.h>
 #include <linux/spinlock.h>
+#include <linux/ftrace.h>
 
 static noinline void __down(struct semaphore *sem);
 static noinline int __down_interruptible(struct semaphore *sem);
@@ -53,6 +54,7 @@ void down(struct semaphore *sem)
 {
         unsigned long flags;
 
+        ftrace_special(sem->count, 0, __LINE__);
         spin_lock_irqsave(&sem->lock, flags);
         if (likely(sem->count > 0))
                 sem->count--;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2824cf48cdca..3271916ff033 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -901,7 +901,7 @@ tracing_sched_switch_trace(struct trace_array *tr,
         entry->ctx.next_pid     = next->pid;
         entry->ctx.next_prio    = next->prio;
         entry->ctx.next_state   = next->state;
-        __trace_stack(tr, data, flags, 4);
+        __trace_stack(tr, data, flags, 5);
         __raw_spin_unlock(&data->lock);
         raw_local_irq_restore(irq_flags);
 }
@@ -927,7 +927,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
         entry->ctx.next_pid     = wakee->pid;
         entry->ctx.next_prio    = wakee->prio;
         entry->ctx.next_state   = wakee->state;
-        __trace_stack(tr, data, flags, 5);
+        __trace_stack(tr, data, flags, 6);
         __raw_spin_unlock(&data->lock);
         raw_local_irq_restore(irq_flags);
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f5de0601b408..c460e85e94ed 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -51,7 +51,7 @@ struct special_entry {
  * Stack-trace entry:
  */
 
-#define FTRACE_STACK_ENTRIES    5
+#define FTRACE_STACK_ENTRIES    8
 
 struct stack_entry {
         unsigned long           caller[FTRACE_STACK_ENTRIES];