From: Mathieu Desnoyers mathieu.desnoyers@efficios.com
mainline inclusion from mainline-5.4-rc1 commit 09554009c0cad4cb2223dd943c813c9257c6883a category: bugfix bugzilla: 28332 CVE: NA
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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.c... 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 dd27e632..bcd0ff7 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.