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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2016-04-13 11:05:20 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-04-15 18:01:48 +0200 |
| commit | 8497695243f70fd19ed6cf28b63584f1b608b5f9 (patch) | |
| tree | 4e7dd1e66cdb04771e40ea0dd18f92c9d3d0fc8b /arch | |
| parent | s390/dcssblk: fix possible deadlock in remove vs. per-device attributes (diff) | |
| download | linux-8497695243f70fd19ed6cf28b63584f1b608b5f9.tar.xz linux-8497695243f70fd19ed6cf28b63584f1b608b5f9.zip | |
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 <heiko.carstens@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/lib/spinlock.c | 1 |
1 files changed, 1 insertions, 0 deletions
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)) { |