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Subject[tip: sched/urgent] sched/membarrier: Remove redundant check
The following commit has been merged into the sched/urgent branch of tip:

Commit-ID: 09554009c0cad4cb2223dd943c813c9257c6883a
Gitweb: https://git.kernel.org/tip/09554009c0cad4cb2223dd943c813c9257c6883a
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
AuthorDate: Thu, 19 Sep 2019 13:37:00 -04:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 25 Sep 2019 17:42:30 +02:00

sched/membarrier: Remove redundant check

Checking that the number of threads is 1 is redundant with checking
mm_users == 1.

No change in functionality intended.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/membarrier.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index d48b95f..7ccbd0e 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -186,7 +186,7 @@ static int membarrier_register_global_expedited(void)
MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY)
return 0;
atomic_or(MEMBARRIER_STATE_GLOBAL_EXPEDITED, &mm->membarrier_state);
- if (atomic_read(&mm->mm_users) == 1 && get_nr_threads(p) == 1) {
+ if (atomic_read(&mm->mm_users) == 1) {
/*
* For single mm user, single threaded process, we can
* simply issue a memory barrier after setting
@@ -232,7 +232,7 @@ static int membarrier_register_private_expedited(int flags)
if (flags & MEMBARRIER_FLAG_SYNC_CORE)
atomic_or(MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE,
&mm->membarrier_state);
- if (!(atomic_read(&mm->mm_users) == 1 && get_nr_threads(p) == 1)) {
+ if (atomic_read(&mm->mm_users) != 1) {
/*
* Ensure all future scheduler executions will observe the
* new thread flag state for this process.
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