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    Subject[RFC PATCH for 5.4 2/7] Cleanup: sched/membarrier: Remove redundant check
    Date
    Checking that the number of threads is 1 is redundant with checking
    mm_users == 1.

    Suggested-by: Oleg Nesterov <oleg@redhat.com>
    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
    Cc: Chris Metcalf <cmetcalf@ezchip.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Kirill Tkhai <tkhai@yandex.ru>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: 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 5110d91b1b0e..7e0a0d6535f3 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.
    --
    2.17.1
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