diff options
| author | Gerald Schaefer | 2010-02-26 22:37:40 +0100 |
|---|---|---|
| committer | Martin Schwidefsky | 2010-02-26 22:37:31 +0100 |
| commit | 59b697874529f5c3cbcaf5816b3d6c584af521e8 (patch) | |
| tree | c395952c2a0bb9a3027a37a30dd37cc93b1a7c3f /arch/s390/lib | |
| parent | 8387c736fcbaec17890b8d075ee4f4623518b54a (diff) | |
[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.c | 53 |
1 files changed, 37 insertions, 16 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index cff327f109a8..91754ffb9203 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); |