From 987805770a3fd654cc66cc0e59aa7ffb2fde8948 Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 5 Feb 2020 12:30:46 +0800
Subject: [PATCH] sched/membarrier: Remove redundant check

mainline inclusion
from mainline-5.4-rc1
commit 09554009c0cad4cb2223dd943c813c9257c6883a
category: bugfix
bugzilla: 28332
CVE: NA

-------------------------------------------------

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>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Reviewed-By: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 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 dd27e632b1ba..bcd0ff7e1644 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -195,7 +195,7 @@ 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
@@ -241,7 +241,7 @@ 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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