[tip:perf/core] perf/callchain: Replace rcu_assign_pointer() with RCU_INIT_POINTER()

[tip-bot for Andreea-Cristina Bernat <tipbot@zytor.com>]

Commit-ID:  e0455e194a5e0cf49bc7596a20d4f7e47995b9c6
Gitweb:     http://git.kernel.org/tip/e0455e194a5e0cf49bc7596a20d4f7e47995b9c6
Author:     Andreea-Cristina Bernat <bernat.ada@gmail.com>
AuthorDate: Fri, 22 Aug 2014 17:15:36 +0300
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Sep 2014 06:53:04 +0200

perf/callchain: Replace rcu_assign_pointer() with RCU_INIT_POINTER()

The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:

 "1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"

it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

 The following Coccinelle semantic patch was used:
 @@
 @@

 - rcu_assign_pointer
 + RCU_INIT_POINTER
   (..., NULL)

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: paulmck@linux.vnet.ibm.com
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: http://lkml.kernel.org/r/20140822141536.GA32051@ada
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/events/callchain.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 97b67df..f2a88de 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -52,7 +52,7 @@ static void release_callchain_buffers(void)
 	struct callchain_cpus_entries *entries;
 
 	entries = callchain_cpus_entries;
-	rcu_assign_pointer(callchain_cpus_entries, NULL);
+	RCU_INIT_POINTER(callchain_cpus_entries, NULL);
 	call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
 }