diff options
| author |   Will Deacon <will.deacon@arm.com> | 2013-10-09 15:54:27 +0100 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2013-10-24 15:46:34 +0100 |
| commit | 5686b06cea34e31ec0a549d9b5ac00776e8e8d6d (patch) | |
| tree | 69f5fa9d9ccc89232bea8c1e1337a4217751ba3d | |
| parent | arm64: locks: introduce ticket-based spinlock implementation (diff) | |
| download | linux-dev-5686b06cea34e31ec0a549d9b5ac00776e8e8d6d.tar.xz linux-dev-5686b06cea34e31ec0a549d9b5ac00776e8e8d6d.zip | |
arm64: lockref: add support for lockless lockrefs using cmpxchg
Our spinlocks are only 32-bit (2x16-bit tickets) and our cmpxchg can
deal with 8-bytes (as one would hope!).
This patch wires up the cmpxchg-based lockless lockref implementation
for arm64.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm64/Kconfig | 1 | ||||
| -rw-r--r-- | arch/arm64/include/asm/spinlock.h | 8 |
2 files changed, 7 insertions, 2 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c04454876bcb..9e8233b3f188 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1,6 +1,7 @@ config ARM64 def_bool y select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE + select ARCH_USE_CMPXCHG_LOCKREF select ARCH_WANT_OPTIONAL_GPIOLIB select ARCH_WANT_COMPAT_IPC_PARSE_VERSION select ARCH_WANT_FRAME_POINTERS diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index 525dd535443e..3d5cf064d7a1 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -92,10 +92,14 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) : "memory"); } +static inline int arch_spin_value_unlocked(arch_spinlock_t lock) +{ + return lock.owner == lock.next; +} + static inline int arch_spin_is_locked(arch_spinlock_t *lock) { - arch_spinlock_t lockval = ACCESS_ONCE(*lock); - return lockval.owner != lockval.next; + return !arch_spin_value_unlocked(ACCESS_ONCE(*lock)); } static inline int arch_spin_is_contended(arch_spinlock_t *lock) |