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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2014-05-06 19:41:36 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2014-05-20 08:58:52 +0200
commit2e4006b34d06681ed95d55510d4450f29a13c417 (patch)
tree0ff439559cfcfc2bac5eb1b41d6412694fd49a03 /arch/s390/lib
parentf1a858206804a5a694f30196e50756b86eb7d68c (diff)
downloadlinux-2e4006b34d06681ed95d55510d4450f29a13c417.tar.bz2
s390/spinlock: fix system hang with spin_retry <= 0
On LPAR, when spin_retry is set to <= 0, arch_spin_lock_wait() and arch_spin_lock_wait_flags() may end up in a while(1) loop w/o doing any compare and swap operation. To fix this, use do/while instead of for loop. Signed-off-by: Gerald Schaefer <gerald.schaefer@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.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index 3ca9de4d9cb9..3f0e682b7e62 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -26,19 +26,20 @@ __setup("spin_retry=", spin_retry_setup);
void arch_spin_lock_wait(arch_spinlock_t *lp)
{
- int count = spin_retry;
unsigned int cpu = SPINLOCK_LOCKVAL;
unsigned int owner;
+ int count;
while (1) {
owner = lp->lock;
if (!owner || smp_vcpu_scheduled(~owner)) {
- for (count = spin_retry; count > 0; count--) {
+ count = spin_retry;
+ do {
if (arch_spin_is_locked(lp))
continue;
if (_raw_compare_and_swap(&lp->lock, 0, cpu))
return;
- }
+ } while (count-- > 0);
if (MACHINE_IS_LPAR)
continue;
}
@@ -53,22 +54,23 @@ EXPORT_SYMBOL(arch_spin_lock_wait);
void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
- int count = spin_retry;
unsigned int cpu = SPINLOCK_LOCKVAL;
unsigned int owner;
+ int count;
local_irq_restore(flags);
while (1) {
owner = lp->lock;
if (!owner || smp_vcpu_scheduled(~owner)) {
- for (count = spin_retry; count > 0; count--) {
+ count = spin_retry;
+ do {
if (arch_spin_is_locked(lp))
continue;
local_irq_disable();
if (_raw_compare_and_swap(&lp->lock, 0, cpu))
return;
local_irq_restore(flags);
- }
+ } while (count-- > 0);
if (MACHINE_IS_LPAR)
continue;
}