[tip:sched/core] sched/fair: Replace rcu_assign_pointer() with RCU_INIT_POINTER()

From: tip-bot for Andreea-Cristina Bernat
Date: Fri Sep 05 2014 - 02:17:54 EST


Commit-ID: 35b123e2f701b28977db2cde7dbbdb3fad28cad1
Gitweb: http://git.kernel.org/tip/35b123e2f701b28977db2cde7dbbdb3fad28cad1
Author: Andreea-Cristina Bernat <bernat.ada@xxxxxxxxx>
AuthorDate: Fri, 22 Aug 2014 17:50:43 +0300
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 5 Sep 2014 08:11:57 +0200

sched/fair: 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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20140822145043.GA580@ada
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d3427a8..02fc949 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1780,7 +1780,7 @@ void task_numa_free(struct task_struct *p)
list_del(&p->numa_entry);
grp->nr_tasks--;
spin_unlock_irqrestore(&grp->lock, flags);
- rcu_assign_pointer(p->numa_group, NULL);
+ RCU_INIT_POINTER(p->numa_group, NULL);
put_numa_group(grp);
}

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