From: Mathieu Desnoyers <mathieu.desnoy...@efficios.com> [ Upstream commit fc0d77387cb5ae883fd774fc559e056a8dde024c ]
Fix a logic flaw in the way membarrier_register_private_expedited() handles ready state checks for private expedited sync core and private expedited registrations. If a private expedited membarrier registration is first performed, and then a private expedited sync_core registration is performed, the ready state check will skip the second registration when it really should not. Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Chris Metcalf <cmetc...@ezchip.com> Cc: Christoph Lameter <c...@linux.com> Cc: Eric W. Biederman <ebied...@xmission.com> Cc: Kirill Tkhai <tk...@yandex.ru> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mike Galbraith <efa...@gmx.de> Cc: Oleg Nesterov <o...@redhat.com> Cc: Paul E. McKenney <paul...@linux.ibm.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Russell King - ARM Linux admin <li...@armlinux.org.uk> Cc: Thomas Gleixner <t...@linutronix.de> Link: https://lkml.kernel.org/r/20190919173705.2181-2-mathieu.desnoy...@efficios.com Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- kernel/sched/membarrier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 76e0eaf4654e0..dd27e632b1bab 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -235,7 +235,7 @@ static int membarrier_register_private_expedited(int flags) * groups, which use the same mm. (CLONE_VM but not * CLONE_THREAD). */ - if (atomic_read(&mm->membarrier_state) & state) + if ((atomic_read(&mm->membarrier_state) & state) == state) return 0; atomic_or(MEMBARRIER_STATE_PRIVATE_EXPEDITED, &mm->membarrier_state); if (flags & MEMBARRIER_FLAG_SYNC_CORE) -- 2.20.1
