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authorChristian Borntraeger <borntraeger@de.ibm.com>2015-09-11 16:09:56 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2015-10-14 14:32:00 +0200
commite0af21c56ddd592b33f74f986a2cb4478b10786e (patch)
treec5dd2779855656d9fda7eb7d1b90218b2a3f4599 /arch/s390/lib
parent9a21268360f5438796fa935e0b2e9317187ef8f4 (diff)
downloadlinux-linaro-stable-e0af21c56ddd592b33f74f986a2cb4478b10786e.tar.gz
s390/spinlock: use correct barriers
_raw_write_lock_wait first sets the high order bit to indicate a pending writer and then waits for the reader to drop to zero. smp_rmb by definition only orders reads against reads. Let's use a full smp_mb instead. As right now smp_rmb is implemented as full serialization, this needs no stable backport, but this patch will be necessary if we reimplement smp_rmb. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib')
-rw-r--r--arch/s390/lib/spinlock.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index d6c9991f7797..427aa44b3505 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -197,7 +197,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev)
}
old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner);
- smp_rmb();
+ smp_mb();
if ((int) old >= 0) {
prev = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
old = prev;
@@ -231,7 +231,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw)
_raw_compare_and_swap(&rw->lock, old, old | 0x80000000))
prev = old;
else
- smp_rmb();
+ smp_mb();
if ((old & 0x7fffffff) == 0 && (int) prev >= 0)
break;
if (MACHINE_HAS_CAD)