diff options
Diffstat (limited to 'arch/s390/lib/spinlock.c')
| -rw-r--r-- | arch/s390/lib/spinlock.c | 45 |
1 files changed, 32 insertions, 13 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index 427aa44b3505..d4549c964589 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -37,12 +37,22 @@ static inline void _raw_compare_and_delay(unsigned int *lock, unsigned int old) asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock)); } +static inline int cpu_is_preempted(int cpu) +{ + if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu)) + return 0; + if (smp_vcpu_scheduled(cpu)) + return 0; + return 1; +} + void arch_spin_lock_wait(arch_spinlock_t *lp) { unsigned int cpu = SPINLOCK_LOCKVAL; unsigned int owner; - int count; + int count, first_diag; + first_diag = 1; while (1) { owner = ACCESS_ONCE(lp->lock); /* Try to get the lock if it is free. */ @@ -51,9 +61,10 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) return; continue; } - /* Check if the lock owner is running. */ - if (!smp_vcpu_scheduled(~owner)) { + /* First iteration: check if the lock owner is running. */ + if (first_diag && cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); + first_diag = 0; continue; } /* Loop for a while on the lock value. */ @@ -67,10 +78,13 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) continue; /* * For multiple layers of hypervisors, e.g. z/VM + LPAR - * yield the CPU if the lock is still unavailable. + * yield the CPU unconditionally. For LPAR rely on the + * sense running status. */ - if (!MACHINE_IS_LPAR) + if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); + first_diag = 0; + } } } EXPORT_SYMBOL(arch_spin_lock_wait); @@ -79,9 +93,10 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) { unsigned int cpu = SPINLOCK_LOCKVAL; unsigned int owner; - int count; + int count, first_diag; local_irq_restore(flags); + first_diag = 1; while (1) { owner = ACCESS_ONCE(lp->lock); /* Try to get the lock if it is free. */ @@ -92,8 +107,9 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) local_irq_restore(flags); } /* Check if the lock owner is running. */ - if (!smp_vcpu_scheduled(~owner)) { + if (first_diag && cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); + first_diag = 0; continue; } /* Loop for a while on the lock value. */ @@ -107,10 +123,13 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) continue; /* * For multiple layers of hypervisors, e.g. z/VM + LPAR - * yield the CPU if the lock is still unavailable. + * yield the CPU unconditionally. For LPAR rely on the + * sense running status. */ - if (!MACHINE_IS_LPAR) + if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) { smp_yield_cpu(~owner); + first_diag = 0; + } } } EXPORT_SYMBOL(arch_spin_lock_wait_flags); @@ -145,7 +164,7 @@ void _raw_read_lock_wait(arch_rwlock_t *rw) owner = 0; while (1) { if (count-- <= 0) { - if (owner && !smp_vcpu_scheduled(~owner)) + if (owner && cpu_is_preempted(~owner)) smp_yield_cpu(~owner); count = spin_retry; } @@ -191,7 +210,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev) owner = 0; while (1) { if (count-- <= 0) { - if (owner && !smp_vcpu_scheduled(~owner)) + if (owner && cpu_is_preempted(~owner)) smp_yield_cpu(~owner); count = spin_retry; } @@ -221,7 +240,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw) owner = 0; while (1) { if (count-- <= 0) { - if (owner && !smp_vcpu_scheduled(~owner)) + if (owner && cpu_is_preempted(~owner)) smp_yield_cpu(~owner); count = spin_retry; } @@ -265,7 +284,7 @@ void arch_lock_relax(unsigned int cpu) { if (!cpu) return; - if (MACHINE_IS_LPAR && smp_vcpu_scheduled(~cpu)) + if (MACHINE_IS_LPAR && !cpu_is_preempted(~cpu)) return; smp_yield_cpu(~cpu); } |