diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-05-16 09:11:12 -0400 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-05-20 02:58:55 -0400 |
| commit | 470ada6b1a1d80a173586c036f84e2c3a486ebf9 (patch) | |
| tree | 44fd6a61db1666e1c5239392b17b5c6f21ec40b0 /arch/s390/lib/spinlock.c | |
| parent | 939c5ae4029e1679bb93f7d09afb8c831db985bd (diff) | |
s390/spinlock: refactor arch_spin_lock_wait[_flags]
Reorder the spinlock wait code to make it more readable.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib/spinlock.c')
| -rw-r--r-- | arch/s390/lib/spinlock.c | 81 |
1 files changed, 47 insertions, 34 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index 1dd282c742b5..5b0e445bc3f3 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c | |||
| @@ -31,23 +31,31 @@ void arch_spin_lock_wait(arch_spinlock_t *lp) | |||
| 31 | int count; | 31 | int count; |
| 32 | 32 | ||
| 33 | while (1) { | 33 | while (1) { |
| 34 | owner = lp->lock; | 34 | owner = ACCESS_ONCE(lp->lock); |
| 35 | if (!owner || smp_vcpu_scheduled(~owner)) { | 35 | /* Try to get the lock if it is free. */ |
| 36 | count = spin_retry; | 36 | if (!owner) { |
| 37 | do { | 37 | if (_raw_compare_and_swap(&lp->lock, 0, cpu)) |
| 38 | if (arch_spin_is_locked(lp)) | 38 | return; |
| 39 | continue; | 39 | continue; |
| 40 | if (_raw_compare_and_swap(&lp->lock, 0, cpu)) | ||
| 41 | return; | ||
| 42 | } while (count-- > 0); | ||
| 43 | if (MACHINE_IS_LPAR) | ||
| 44 | continue; | ||
| 45 | } | 40 | } |
| 46 | owner = lp->lock; | 41 | /* Check if the lock owner is running. */ |
| 47 | if (owner) | 42 | if (!smp_vcpu_scheduled(~owner)) { |
| 43 | smp_yield_cpu(~owner); | ||
| 44 | continue; | ||
| 45 | } | ||
| 46 | /* Loop for a while on the lock value. */ | ||
| 47 | count = spin_retry; | ||
| 48 | do { | ||
| 49 | owner = ACCESS_ONCE(lp->lock); | ||
| 50 | } while (owner && count-- > 0); | ||
| 51 | if (!owner) | ||
| 52 | continue; | ||
| 53 | /* | ||
| 54 | * For multiple layers of hypervisors, e.g. z/VM + LPAR | ||
| 55 | * yield the CPU if the lock is still unavailable. | ||
| 56 | */ | ||
| 57 | if (!MACHINE_IS_LPAR) | ||
| 48 | smp_yield_cpu(~owner); | 58 | smp_yield_cpu(~owner); |
| 49 | if (_raw_compare_and_swap(&lp->lock, 0, cpu)) | ||
| 50 | return; | ||
| 51 | } | 59 | } |
| 52 | } | 60 | } |
| 53 | EXPORT_SYMBOL(arch_spin_lock_wait); | 61 | EXPORT_SYMBOL(arch_spin_lock_wait); |
| @@ -60,27 +68,32 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags) | |||
| 60 | 68 | ||
| 61 | local_irq_restore(flags); | 69 | local_irq_restore(flags); |
| 62 | while (1) { | 70 | while (1) { |
| 63 | owner = lp->lock; | 71 | owner = ACCESS_ONCE(lp->lock); |
| 64 | if (!owner || smp_vcpu_scheduled(~owner)) { | 72 | /* Try to get the lock if it is free. */ |
| 65 | count = spin_retry; | 73 | if (!owner) { |
| 66 | do { | 74 | local_irq_disable(); |
| 67 | if (arch_spin_is_locked(lp)) | 75 | if (_raw_compare_and_swap(&lp->lock, 0, cpu)) |
| 68 | continue; | 76 | return; |
| 69 | local_irq_disable(); | 77 | local_irq_restore(flags); |
| 70 | if (_raw_compare_and_swap(&lp->lock, 0, cpu)) | ||
| 71 | return; | ||
| 72 | local_irq_restore(flags); | ||
| 73 | } while (count-- > 0); | ||
| 74 | if (MACHINE_IS_LPAR) | ||
| 75 | continue; | ||
| 76 | } | 78 | } |
| 77 | owner = lp->lock; | 79 | /* Check if the lock owner is running. */ |
| 78 | if (owner) | 80 | if (!smp_vcpu_scheduled(~owner)) { |
| 81 | smp_yield_cpu(~owner); | ||
| 82 | continue; | ||
| 83 | } | ||
| 84 | /* Loop for a while on the lock value. */ | ||
| 85 | count = spin_retry; | ||
| 86 | do { | ||
| 87 | owner = ACCESS_ONCE(lp->lock); | ||
| 88 | } while (owner && count-- > 0); | ||
| 89 | if (!owner) | ||
| 90 | continue; | ||
| 91 | /* | ||
| 92 | * For multiple layers of hypervisors, e.g. z/VM + LPAR | ||
| 93 | * yield the CPU if the lock is still unavailable. | ||
| 94 | */ | ||
| 95 | if (!MACHINE_IS_LPAR) | ||
| 79 | smp_yield_cpu(~owner); | 96 | smp_yield_cpu(~owner); |
| 80 | local_irq_disable(); | ||
| 81 | if (_raw_compare_and_swap(&lp->lock, 0, cpu)) | ||
| 82 | return; | ||
| 83 | local_irq_restore(flags); | ||
| 84 | } | 97 | } |
| 85 | } | 98 | } |
| 86 | EXPORT_SYMBOL(arch_spin_lock_wait_flags); | 99 | EXPORT_SYMBOL(arch_spin_lock_wait_flags); |