From 8497695243f70fd19ed6cf28b63584f1b608b5f9 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 13 Apr 2016 11:05:20 +0200 Subject: [PATCH] s390/spinlock: avoid yield to non existent cpu arch_spin_lock_wait_flags() checks if a spinlock is not held before trying a compare and swap instruction. If the lock is unlocked it tries the compare and swap instruction, however if a different cpu grabbed the lock in the meantime the instruction will fail as expected. Subsequently the arch_spin_lock_wait_flags() incorrectly tries to figure out if the cpu that holds the lock is running. However it is using the wrong cpu number for this (-1) and then will also yield the current cpu to the wrong cpu. Fix this by adding a missing continue statement. Fixes: 470ada6b1a1d ("s390/spinlock: refactor arch_spin_lock_wait[_flags]") Signed-off-by: Heiko Carstens Acked-by: Martin Schwidefsky --- arch/s390/lib/spinlock.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index d4549c964589..e5f50a7d2f4e 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -105,6 +105,7 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) if (_raw_compare_and_swap(&lp->lock, 0, cpu)) return; local_irq_restore(flags); + continue; } /* Check if the lock owner is running. */ if (first_diag && cpu_is_preempted(~owner)) { -- 2.30.2