From bbae71bf9c2fe90dc5642d4cddbbc1994861fd92 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 22 Sep 2014 16:34:38 +0200 Subject: 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 --- arch/s390/lib/spinlock.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'arch/s390/lib') 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; -- cgit v1.2.3