Subject: [PATCH 2/2] ftrace: fix unlocking of hash

From: Steven Rostedt <[email-masked]>
Date: Sat, 06 Sep 2008 01:06:04 -0400

This must be brown paper bag week for Steven Rostedt!

While working on ftrace for PPC, I discovered that the hash locking done
when CONFIG_FTRACE_MCOUNT_RECORD is not set, is totally incorrect.

With a cut and paste error, I had the hash lock macro to lock for both
hash_lock _and_ hash_unlock!

This bug did not affect x86 since this bug was introduced when
CONFIG_FTRACE_MCOUNT_RECORD was added to x86.

Signed-off-by: Steven Rostedt <[email-masked]>
---
 kernel/trace/ftrace.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-tip.git/kernel/trace/ftrace.c
===================================================================
--- linux-tip.git.orig/kernel/trace/ftrace.c	2008-09-05 21:53:46.000000000 -0700
+++ linux-tip.git/kernel/trace/ftrace.c	2008-09-05 21:57:57.000000000 -0700
@@ -170,7 +170,8 @@ static int __unregister_ftrace_function(
  */
 static DEFINE_SPINLOCK(ftrace_hash_lock);
 #define ftrace_hash_lock(flags)	  spin_lock_irqsave(&ftrace_hash_lock, flags)
-#define ftrace_hash_unlock(flags) spin_lock_irqsave(&ftrace_hash_lock, flags)
+#define ftrace_hash_unlock(flags) \
+			spin_unlock_irqrestore(&ftrace_hash_lock, flags)
 #else
 /* This is protected via the ftrace_lock with MCOUNT_RECORD. */
 #define ftrace_hash_lock(flags)   do { (void)(flags); } while (0)

--