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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-03 10:26:41 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-03 10:26:41 -0700 |
commit | 8f5759aeb88a47448cd92ab55a016d013b154a98 (patch) | |
tree | a9c0536e10300a95292b99332171837675af1e16 /arch/s390/lib/spinlock.c | |
parent | e5c4ecdc55b6d824365ba7964bcd3185223f9688 (diff) | |
parent | 63aef00b55d37e9fad837a8b38a2c261f0d32041 (diff) | |
download | linux-8f5759aeb88a47448cd92ab55a016d013b154a98.tar.bz2 |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux into next
Pull first set of s390 updates from Martin Schwidefsky:
"The biggest change in this patchset is conversion from the bootmem
bitmaps to the memblock code. This conversion requires two common
code patches to introduce the 'physmem' memblock list.
We experimented with ticket spinlocks but in the end decided against
them as they perform poorly on virtualized systems. But the spinlock
cleanup and some small improvements are included.
The uaccess code got another optimization, the get_user/put_user calls
are now inline again for kernel compiles targeted at z10 or newer
machines. This makes the text segment shorter and the code gets a
little bit faster.
And as always some bug fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (31 commits)
s390/lowcore: replace lowcore irb array with a per-cpu variable
s390/lowcore: reserve 96 bytes for IRB in lowcore
s390/facilities: remove extract-cpu-time facility check
s390: require mvcos facility for z10 and newer machines
s390/boot: fix boot of compressed kernel built with gcc 4.9
s390/cio: remove weird assignment during argument evaluation
s390/time: cast tv_nsec to u64 prior to shift in update_vsyscall
s390/oprofile: make return of 0 explicit
s390/spinlock: refactor arch_spin_lock_wait[_flags]
s390/rwlock: add missing local_irq_restore calls
s390/spinlock,rwlock: always to a load-and-test first
s390/cio: fix multiple structure definitions
s390/spinlock: fix system hang with spin_retry <= 0
s390/appldata: add slab.h for kzalloc/kfree
s390/uaccess: provide inline variants of get_user/put_user
s390/pci: add some new arch specific pci attributes
s390/pci: use pdev->dev.groups for attribute creation
s390/pci: use macro for attribute creation
s390/pci: improve state check when processing hotplug events
s390: split TIF bits into CIF, PIF and TIF bits
...
Diffstat (limited to 'arch/s390/lib/spinlock.c')
-rw-r--r-- | arch/s390/lib/spinlock.c | 157 |
1 files changed, 87 insertions, 70 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index f709983f41f8..5b0e445bc3f3 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -26,83 +26,81 @@ __setup("spin_retry=", spin_retry_setup); void arch_spin_lock_wait(arch_spinlock_t *lp) { - int count = spin_retry; - unsigned int cpu = ~smp_processor_id(); + unsigned int cpu = SPINLOCK_LOCKVAL; unsigned int owner; + int count; while (1) { - 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; + owner = ACCESS_ONCE(lp->lock); + /* Try to get the lock if it is free. */ + if (!owner) { + if (_raw_compare_and_swap(&lp->lock, 0, cpu)) + return; + continue; } - owner = lp->owner_cpu; - if (owner) + /* Check if the lock owner is running. */ + if (!smp_vcpu_scheduled(~owner)) { + smp_yield_cpu(~owner); + continue; + } + /* Loop for a while on the lock value. */ + count = spin_retry; + do { + owner = ACCESS_ONCE(lp->lock); + } while (owner && count-- > 0); + if (!owner) + continue; + /* + * For multiple layers of hypervisors, e.g. z/VM + LPAR + * yield the CPU if the lock is still unavailable. + */ + if (!MACHINE_IS_LPAR) smp_yield_cpu(~owner); - if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0) - return; } } EXPORT_SYMBOL(arch_spin_lock_wait); 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 cpu = SPINLOCK_LOCKVAL; unsigned int owner; + int count; local_irq_restore(flags); while (1) { - 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; + owner = ACCESS_ONCE(lp->lock); + /* Try to get the lock if it is free. */ + if (!owner) { + local_irq_disable(); + if (_raw_compare_and_swap(&lp->lock, 0, cpu)) + return; + local_irq_restore(flags); } - owner = lp->owner_cpu; - if (owner) + /* Check if the lock owner is running. */ + if (!smp_vcpu_scheduled(~owner)) { smp_yield_cpu(~owner); - local_irq_disable(); - if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0) - return; - local_irq_restore(flags); - } -} -EXPORT_SYMBOL(arch_spin_lock_wait_flags); - -int arch_spin_trylock_retry(arch_spinlock_t *lp) -{ - unsigned int cpu = ~smp_processor_id(); - int count; - - 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 1; + } + /* Loop for a while on the lock value. */ + count = spin_retry; + do { + owner = ACCESS_ONCE(lp->lock); + } while (owner && count-- > 0); + if (!owner) + continue; + /* + * For multiple layers of hypervisors, e.g. z/VM + LPAR + * yield the CPU if the lock is still unavailable. + */ + if (!MACHINE_IS_LPAR) + smp_yield_cpu(~owner); } - return 0; } -EXPORT_SYMBOL(arch_spin_trylock_retry); +EXPORT_SYMBOL(arch_spin_lock_wait_flags); -void arch_spin_relax(arch_spinlock_t *lock) +void arch_spin_relax(arch_spinlock_t *lp) { - unsigned int cpu = lock->owner_cpu; + unsigned int cpu = lp->lock; if (cpu != 0) { if (MACHINE_IS_VM || MACHINE_IS_KVM || !smp_vcpu_scheduled(~cpu)) @@ -111,6 +109,17 @@ void arch_spin_relax(arch_spinlock_t *lock) } EXPORT_SYMBOL(arch_spin_relax); +int arch_spin_trylock_retry(arch_spinlock_t *lp) +{ + int count; + + for (count = spin_retry; count > 0; count--) + if (arch_spin_trylock_once(lp)) + return 1; + return 0; +} +EXPORT_SYMBOL(arch_spin_trylock_retry); + void _raw_read_lock_wait(arch_rwlock_t *rw) { unsigned int old; @@ -121,10 +130,10 @@ void _raw_read_lock_wait(arch_rwlock_t *rw) smp_yield(); count = spin_retry; } - if (!arch_read_can_lock(rw)) + old = ACCESS_ONCE(rw->lock); + if ((int) old < 0) continue; - old = rw->lock & 0x7fffffffU; - if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old) + if (_raw_compare_and_swap(&rw->lock, old, old + 1)) return; } } @@ -141,12 +150,13 @@ void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags) smp_yield(); count = spin_retry; } - if (!arch_read_can_lock(rw)) + old = ACCESS_ONCE(rw->lock); + if ((int) old < 0) continue; - old = rw->lock & 0x7fffffffU; local_irq_disable(); - if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old) + if (_raw_compare_and_swap(&rw->lock, old, old + 1)) return; + local_irq_restore(flags); } } EXPORT_SYMBOL(_raw_read_lock_wait_flags); @@ -157,10 +167,10 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw) int count = spin_retry; while (count-- > 0) { - if (!arch_read_can_lock(rw)) + old = ACCESS_ONCE(rw->lock); + if ((int) old < 0) continue; - old = rw->lock & 0x7fffffffU; - if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old) + if (_raw_compare_and_swap(&rw->lock, old, old + 1)) return 1; } return 0; @@ -169,6 +179,7 @@ EXPORT_SYMBOL(_raw_read_trylock_retry); void _raw_write_lock_wait(arch_rwlock_t *rw) { + unsigned int old; int count = spin_retry; while (1) { @@ -176,9 +187,10 @@ void _raw_write_lock_wait(arch_rwlock_t *rw) smp_yield(); count = spin_retry; } - if (!arch_write_can_lock(rw)) + old = ACCESS_ONCE(rw->lock); + if (old) continue; - if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0) + if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000)) return; } } @@ -186,6 +198,7 @@ EXPORT_SYMBOL(_raw_write_lock_wait); void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags) { + unsigned int old; int count = spin_retry; local_irq_restore(flags); @@ -194,23 +207,27 @@ void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags) smp_yield(); count = spin_retry; } - if (!arch_write_can_lock(rw)) + old = ACCESS_ONCE(rw->lock); + if (old) continue; local_irq_disable(); - if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0) + if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000)) return; + local_irq_restore(flags); } } EXPORT_SYMBOL(_raw_write_lock_wait_flags); int _raw_write_trylock_retry(arch_rwlock_t *rw) { + unsigned int old; int count = spin_retry; while (count-- > 0) { - if (!arch_write_can_lock(rw)) + old = ACCESS_ONCE(rw->lock); + if (old) continue; - if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0) + if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000)) return 1; } return 0; |