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>

diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index d48b95f..7ccbd0e 100644 (file)
--- 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.