From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> - Using smp_cond_load_acquire in arch_spin_lock by Peter's advice. - Using __smp_acquire_fence in arch_spin_trylock - Using smp_store_release in arch_spin_unlock All above are just coding conventions and won't affect the function. TODO in smp_cond_load_acquire for architecture: - current csky only has: lr.w val, <p0> sc.w <p0>. val2 (Any other stores to p0 will let sc.w failed) - But smp_cond_load_acquire need: lr.w val, <p0> wfe (Any stores to p0 will send the event to let wfe retired) Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/linux-riscv/CAAhSdy1JHLUFwu7RuCaQ+RUWRBks2KsDva7EpRt8--4ZfofSUQ@xxxxxxxxxxxxxx/T/#m13adac285b7f51f4f879a5d6b65753ecb1a7524e Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> --- arch/csky/include/asm/spinlock.h | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h index 69f5aa249c5f..69677167977a 100644 --- a/arch/csky/include/asm/spinlock.h +++ b/arch/csky/include/asm/spinlock.h @@ -26,10 +26,8 @@ static inline void arch_spin_lock(arch_spinlock_t *lock) : "r"(p), "r"(ticket_next) : "cc"); - while (lockval.tickets.next != lockval.tickets.owner) - lockval.tickets.owner = READ_ONCE(lock->tickets.owner); - - smp_mb(); + smp_cond_load_acquire(&lock->tickets.owner, + VAL == lockval.tickets.next); } static inline int arch_spin_trylock(arch_spinlock_t *lock) @@ -55,15 +53,14 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) } while (!res); if (!contended) - smp_mb(); + __smp_acquire_fence(); return !contended; } static inline void arch_spin_unlock(arch_spinlock_t *lock) { - smp_mb(); - WRITE_ONCE(lock->tickets.owner, lock->tickets.owner + 1); + smp_store_release(&lock->tickets.owner, lock->tickets.owner + 1); } static inline int arch_spin_value_unlocked(arch_spinlock_t lock) -- 2.17.1
