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


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