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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-19 14:29:31 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-25 10:52:05 +0200 |
| commit | d59b93da5e572703e1a7311c13dd3472a4e56e30 (patch) | |
| tree | 4c75073780f54bc9785433256eee3d6d70eaf868 /arch/s390/lib | |
| parent | s390/zcrypt: Fixed possible race condition in zcrypt module handling (diff) | |
| download | linux-d59b93da5e572703e1a7311c13dd3472a4e56e30.tar.xz linux-d59b93da5e572703e1a7311c13dd3472a4e56e30.zip | |
s390/rwlock: use directed yield for write-locked rwlocks
Add an owner field to the arch_rwlock_t to be able to pass the timeslice
of a virtual CPU with diagnose 0x9c to the lock owner in case the rwlock
is write-locked. The undirected yield in case the rwlock is acquired
writable but the lock is read-locked is removed.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib')
| -rw-r--r-- | arch/s390/lib/spinlock.c | 49 |
1 files changed, 30 insertions, 19 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index 5b0e445bc3f3..5f63ac5783cb 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -98,17 +98,6 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) } EXPORT_SYMBOL(arch_spin_lock_wait_flags); -void arch_spin_relax(arch_spinlock_t *lp) -{ - unsigned int cpu = lp->lock; - if (cpu != 0) { - if (MACHINE_IS_VM || MACHINE_IS_KVM || - !smp_vcpu_scheduled(~cpu)) - smp_yield_cpu(~cpu); - } -} -EXPORT_SYMBOL(arch_spin_relax); - int arch_spin_trylock_retry(arch_spinlock_t *lp) { int count; @@ -122,15 +111,18 @@ EXPORT_SYMBOL(arch_spin_trylock_retry); void _raw_read_lock_wait(arch_rwlock_t *rw) { - unsigned int old; + unsigned int owner, old; int count = spin_retry; + owner = 0; while (1) { if (count-- <= 0) { - smp_yield(); + if (owner && !smp_vcpu_scheduled(~owner)) + smp_yield_cpu(~owner); count = spin_retry; } old = ACCESS_ONCE(rw->lock); + owner = ACCESS_ONCE(rw->owner); if ((int) old < 0) continue; if (_raw_compare_and_swap(&rw->lock, old, old + 1)) @@ -141,16 +133,19 @@ EXPORT_SYMBOL(_raw_read_lock_wait); void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags) { - unsigned int old; + unsigned int owner, old; int count = spin_retry; local_irq_restore(flags); + owner = 0; while (1) { if (count-- <= 0) { - smp_yield(); + if (owner && !smp_vcpu_scheduled(~owner)) + smp_yield_cpu(~owner); count = spin_retry; } old = ACCESS_ONCE(rw->lock); + owner = ACCESS_ONCE(rw->owner); if ((int) old < 0) continue; local_irq_disable(); @@ -179,15 +174,18 @@ EXPORT_SYMBOL(_raw_read_trylock_retry); void _raw_write_lock_wait(arch_rwlock_t *rw) { - unsigned int old; + unsigned int owner, old; int count = spin_retry; + owner = 0; while (1) { if (count-- <= 0) { - smp_yield(); + if (owner && !smp_vcpu_scheduled(~owner)) + smp_yield_cpu(~owner); count = spin_retry; } old = ACCESS_ONCE(rw->lock); + owner = ACCESS_ONCE(rw->owner); if (old) continue; if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000)) @@ -198,16 +196,19 @@ EXPORT_SYMBOL(_raw_write_lock_wait); void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags) { - unsigned int old; + unsigned int owner, old; int count = spin_retry; local_irq_restore(flags); + owner = 0; while (1) { if (count-- <= 0) { - smp_yield(); + if (owner && !smp_vcpu_scheduled(~owner)) + smp_yield_cpu(~owner); count = spin_retry; } old = ACCESS_ONCE(rw->lock); + owner = ACCESS_ONCE(rw->owner); if (old) continue; local_irq_disable(); @@ -233,3 +234,13 @@ int _raw_write_trylock_retry(arch_rwlock_t *rw) return 0; } EXPORT_SYMBOL(_raw_write_trylock_retry); + +void arch_lock_relax(unsigned int cpu) +{ + if (!cpu) + return; + if (MACHINE_IS_LPAR && smp_vcpu_scheduled(~cpu)) + return; + smp_yield_cpu(~cpu); +} +EXPORT_SYMBOL(arch_lock_relax); |