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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-22 18:34:38 +0400 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-25 12:52:13 +0400 |
| commit | bbae71bf9c2fe90dc5642d4cddbbc1994861fd92 (patch) | |
| tree | 80ce9213a904817502ffc588eb31d5731cc9a250 /arch/s390/lib | |
| parent | 94232a4332de3bc210e7067fd43521b3eb12336a (diff) | |
| download | linux-bbae71bf9c2fe90dc5642d4cddbbc1994861fd92.tar.xz | |
s390/rwlock: use the interlocked-access facility 1 instructions
Make use of the load-and-add, load-and-or and load-and-and instructions
to atomically update the read-write lock without a compare-and-swap loop.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib')
| -rw-r--r-- | arch/s390/lib/spinlock.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index 01f29bb9c71b..034a35a3e9c1 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -114,6 +114,9 @@ void _raw_read_lock_wait(arch_rwlock_t *rw) unsigned int owner, old; int count = spin_retry; +#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES + __RAW_LOCK(&rw->lock, -1, __RAW_OP_ADD); +#endif owner = 0; while (1) { if (count-- <= 0) { @@ -147,6 +150,35 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw) } EXPORT_SYMBOL(_raw_read_trylock_retry); +#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES + +void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned int prev) +{ + unsigned int owner, old; + int count = spin_retry; + + owner = 0; + while (1) { + if (count-- <= 0) { + if (owner && !smp_vcpu_scheduled(~owner)) + smp_yield_cpu(~owner); + count = spin_retry; + } + old = ACCESS_ONCE(rw->lock); + owner = ACCESS_ONCE(rw->owner); + smp_rmb(); + if ((int) old >= 0) { + prev = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR); + old = prev; + } + if ((old & 0x7fffffff) == 0 && (int) prev >= 0) + break; + } +} +EXPORT_SYMBOL(_raw_write_lock_wait); + +#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */ + void _raw_write_lock_wait(arch_rwlock_t *rw) { unsigned int owner, old, prev; @@ -173,6 +205,8 @@ void _raw_write_lock_wait(arch_rwlock_t *rw) } EXPORT_SYMBOL(_raw_write_lock_wait); +#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */ + int _raw_write_trylock_retry(arch_rwlock_t *rw) { unsigned int old; |