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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2010-02-26 22:37:40 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-02-26 22:37:31 +0100
commit59b697874529f5c3cbcaf5816b3d6c584af521e8 (patch)
treec395952c2a0bb9a3027a37a30dd37cc93b1a7c3f /arch/s390/lib
parent8387c736fcbaec17890b8d075ee4f4623518b54a (diff)
downloadlinux-linaro-android-59b697874529f5c3cbcaf5816b3d6c584af521e8.tar.gz
[S390] spinlock: check virtual cpu running status
This patch introduces a new function that checks the running status of a cpu in a hypervisor. This status is not virtualized, so the check is only correct if running in an LPAR. On acquiring a spinlock, if the cpu holding the lock is scheduled by the hypervisor, we do a busy wait on the lock. If it is not scheduled, we yield over to that cpu. 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.c53
1 files changed, 37 insertions, 16 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index cff327f109a..91754ffb920 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -43,16 +43,24 @@ void arch_spin_lock_wait(arch_spinlock_t *lp)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
+ unsigned int owner;
while (1) {
- if (count-- <= 0) {
- unsigned int owner = lp->owner_cpu;
- if (owner != 0)
- _raw_yield_cpu(~owner);
- count = spin_retry;
+ owner = lp->owner_cpu;
+ if (!owner || smp_vcpu_scheduled(~owner)) {
+ for (count = spin_retry; count > 0; count--) {
+ if (arch_spin_is_locked(lp))
+ continue;
+ if (_raw_compare_and_swap(&lp->owner_cpu, 0,
+ cpu) == 0)
+ return;
+ }
+ if (MACHINE_IS_LPAR)
+ continue;
}
- if (arch_spin_is_locked(lp))
- continue;
+ owner = lp->owner_cpu;
+ if (owner)
+ _raw_yield_cpu(~owner);
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
return;
}
@@ -63,17 +71,27 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
+ unsigned int owner;
local_irq_restore(flags);
while (1) {
- if (count-- <= 0) {
- unsigned int owner = lp->owner_cpu;
- if (owner != 0)
- _raw_yield_cpu(~owner);
- count = spin_retry;
+ owner = lp->owner_cpu;
+ if (!owner || smp_vcpu_scheduled(~owner)) {
+ for (count = spin_retry; count > 0; count--) {
+ if (arch_spin_is_locked(lp))
+ continue;
+ local_irq_disable();
+ if (_raw_compare_and_swap(&lp->owner_cpu, 0,
+ cpu) == 0)
+ return;
+ local_irq_restore(flags);
+ }
+ if (MACHINE_IS_LPAR)
+ continue;
}
- if (arch_spin_is_locked(lp))
- continue;
+ owner = lp->owner_cpu;
+ if (owner)
+ _raw_yield_cpu(~owner);
local_irq_disable();
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
return;
@@ -100,8 +118,11 @@ EXPORT_SYMBOL(arch_spin_trylock_retry);
void arch_spin_relax(arch_spinlock_t *lock)
{
unsigned int cpu = lock->owner_cpu;
- if (cpu != 0)
- _raw_yield_cpu(~cpu);
+ if (cpu != 0) {
+ if (MACHINE_IS_VM || MACHINE_IS_KVM ||
+ !smp_vcpu_scheduled(~cpu))
+ _raw_yield_cpu(~cpu);
+ }
}
EXPORT_SYMBOL(arch_spin_relax);