Commit-ID: 952111d7db02573e7165e338de8d4871fa447b21 Gitweb: http://git.kernel.org/tip/952111d7db02573e7165e338de8d4871fa447b21 Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Thu, 29 Jun 2017 15:53:02 -0700 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Thu, 17 Aug 2017 08:08:59 -0700 arch: Remove spin_unlock_wait() arch-specific definitions There is no agreed-upon definition of spin_unlock_wait()'s semantics, and it appears that all callers could do just as well with a lock/unlock pair. This commit therefore removes the underlying arch-specific arch_spin_unlock_wait() for all architectures providing them. Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: <linux-arch@xxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Cc: Andrea Parri <parri.andrea@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Acked-by: Will Deacon <will.deacon@xxxxxxx> Acked-by: Boqun Feng <boqun.feng@xxxxxxxxx> --- arch/alpha/include/asm/spinlock.h | 5 ---- arch/arc/include/asm/spinlock.h | 5 ---- arch/arm/include/asm/spinlock.h | 16 ---------- arch/arm64/include/asm/spinlock.h | 58 ++++-------------------------------- arch/blackfin/include/asm/spinlock.h | 5 ---- arch/hexagon/include/asm/spinlock.h | 5 ---- arch/ia64/include/asm/spinlock.h | 21 ------------- arch/m32r/include/asm/spinlock.h | 5 ---- arch/metag/include/asm/spinlock.h | 5 ---- arch/mn10300/include/asm/spinlock.h | 5 ---- arch/parisc/include/asm/spinlock.h | 7 ----- arch/powerpc/include/asm/spinlock.h | 33 -------------------- arch/s390/include/asm/spinlock.h | 7 ----- arch/sh/include/asm/spinlock-cas.h | 5 ---- arch/sh/include/asm/spinlock-llsc.h | 5 ---- arch/sparc/include/asm/spinlock_32.h | 5 ---- arch/tile/include/asm/spinlock_32.h | 2 -- arch/tile/include/asm/spinlock_64.h | 2 -- arch/tile/lib/spinlock_32.c | 23 -------------- arch/tile/lib/spinlock_64.c | 22 -------------- arch/xtensa/include/asm/spinlock.h | 5 ---- 21 files changed, 5 insertions(+), 241 deletions(-) diff --git a/arch/alpha/include/asm/spinlock.h b/arch/alpha/include/asm/spinlock.h index a40b9fc..718ac0b 100644 --- a/arch/alpha/include/asm/spinlock.h +++ b/arch/alpha/include/asm/spinlock.h @@ -16,11 +16,6 @@ #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) #define arch_spin_is_locked(x) ((x)->lock != 0) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, !VAL); -} - static inline int arch_spin_value_unlocked(arch_spinlock_t lock) { return lock.lock == 0; diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h index 233d5ff..a325e6a 100644 --- a/arch/arc/include/asm/spinlock.h +++ b/arch/arc/include/asm/spinlock.h @@ -16,11 +16,6 @@ #define arch_spin_is_locked(x) ((x)->slock != __ARCH_SPIN_LOCK_UNLOCKED__) #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->slock, !VAL); -} - #ifdef CONFIG_ARC_HAS_LLSC static inline void arch_spin_lock(arch_spinlock_t *lock) diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h index 4bec454..c030143 100644 --- a/arch/arm/include/asm/spinlock.h +++ b/arch/arm/include/asm/spinlock.h @@ -52,22 +52,6 @@ static inline void dsb_sev(void) * memory. */ -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - u16 owner = READ_ONCE(lock->tickets.owner); - - for (;;) { - arch_spinlock_t tmp = READ_ONCE(*lock); - - if (tmp.tickets.owner == tmp.tickets.next || - tmp.tickets.owner != owner) - break; - - wfe(); - } - smp_acquire__after_ctrl_dep(); -} - #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) static inline void arch_spin_lock(arch_spinlock_t *lock) diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index cae331d..f445bd7 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -26,58 +26,6 @@ * The memory barriers are implicit with the load-acquire and store-release * instructions. */ -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - unsigned int tmp; - arch_spinlock_t lockval; - u32 owner; - - /* - * Ensure prior spin_lock operations to other locks have completed - * on this CPU before we test whether "lock" is locked. - */ - smp_mb(); - owner = READ_ONCE(lock->owner) << 16; - - asm volatile( -" sevl\n" -"1: wfe\n" -"2: ldaxr %w0, %2\n" - /* Is the lock free? */ -" eor %w1, %w0, %w0, ror #16\n" -" cbz %w1, 3f\n" - /* Lock taken -- has there been a subsequent unlock->lock transition? */ -" eor %w1, %w3, %w0, lsl #16\n" -" cbz %w1, 1b\n" - /* - * The owner has been updated, so there was an unlock->lock - * transition that we missed. That means we can rely on the - * store-release of the unlock operation paired with the - * load-acquire of the lock operation to publish any of our - * previous stores to the new lock owner and therefore don't - * need to bother with the writeback below. - */ -" b 4f\n" -"3:\n" - /* - * Serialise against any concurrent lockers by writing back the - * unlocked lock value - */ - ARM64_LSE_ATOMIC_INSN( - /* LL/SC */ -" stxr %w1, %w0, %2\n" - __nops(2), - /* LSE atomics */ -" mov %w1, %w0\n" -" cas %w0, %w0, %2\n" -" eor %w1, %w1, %w0\n") - /* Somebody else wrote to the lock, GOTO 10 and reload the value */ -" cbnz %w1, 2b\n" -"4:" - : "=&r" (lockval), "=&r" (tmp), "+Q" (*lock) - : "r" (owner) - : "memory"); -} #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) @@ -176,7 +124,11 @@ static inline int arch_spin_value_unlocked(arch_spinlock_t lock) static inline int arch_spin_is_locked(arch_spinlock_t *lock) { - smp_mb(); /* See arch_spin_unlock_wait */ + /* + * Ensure prior spin_lock operations to other locks have completed + * on this CPU before we test whether "lock" is locked. + */ + smp_mb(); /* ^^^ */ return !arch_spin_value_unlocked(READ_ONCE(*lock)); } diff --git a/arch/blackfin/include/asm/spinlock.h b/arch/blackfin/include/asm/spinlock.h index c58f4a8..f643143 100644 --- a/arch/blackfin/include/asm/spinlock.h +++ b/arch/blackfin/include/asm/spinlock.h @@ -48,11 +48,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) __raw_spin_unlock_asm(&lock->lock); } -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, !VAL); -} - static inline int arch_read_can_lock(arch_rwlock_t *rw) { return __raw_uncached_fetch_asm(&rw->lock) > 0; diff --git a/arch/hexagon/include/asm/spinlock.h b/arch/hexagon/include/asm/spinlock.h index a1c5578..53a8d58 100644 --- a/arch/hexagon/include/asm/spinlock.h +++ b/arch/hexagon/include/asm/spinlock.h @@ -179,11 +179,6 @@ static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock) */ #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, !VAL); -} - #define arch_spin_is_locked(x) ((x)->lock != 0) #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h index ca9e761..df2c121 100644 --- a/arch/ia64/include/asm/spinlock.h +++ b/arch/ia64/include/asm/spinlock.h @@ -76,22 +76,6 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) ACCESS_ONCE(*p) = (tmp + 2) & ~1; } -static __always_inline void __ticket_spin_unlock_wait(arch_spinlock_t *lock) -{ - int *p = (int *)&lock->lock, ticket; - - ia64_invala(); - - for (;;) { - asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory"); - if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK)) - return; - cpu_relax(); - } - - smp_acquire__after_ctrl_dep(); -} - static inline int __ticket_spin_is_locked(arch_spinlock_t *lock) { long tmp = ACCESS_ONCE(lock->lock); @@ -143,11 +127,6 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock, arch_spin_lock(lock); } -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - __ticket_spin_unlock_wait(lock); -} - #define arch_read_can_lock(rw) (*(volatile int *)(rw) >= 0) #define arch_write_can_lock(rw) (*(volatile int *)(rw) == 0) diff --git a/arch/m32r/include/asm/spinlock.h b/arch/m32r/include/asm/spinlock.h index 323c7fc..a568255 100644 --- a/arch/m32r/include/asm/spinlock.h +++ b/arch/m32r/include/asm/spinlock.h @@ -30,11 +30,6 @@ #define arch_spin_is_locked(x) (*(volatile int *)(&(x)->slock) <= 0) #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->slock, VAL > 0); -} - /** * arch_spin_trylock - Try spin lock and return a result * @lock: Pointer to the lock variable diff --git a/arch/metag/include/asm/spinlock.h b/arch/metag/include/asm/spinlock.h index c0c7a22..ddf7fe5 100644 --- a/arch/metag/include/asm/spinlock.h +++ b/arch/metag/include/asm/spinlock.h @@ -15,11 +15,6 @@ * locked. */ -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, !VAL); -} - #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) diff --git a/arch/mn10300/include/asm/spinlock.h b/arch/mn10300/include/asm/spinlock.h index 9c7b8f7..fe413b4 100644 --- a/arch/mn10300/include/asm/spinlock.h +++ b/arch/mn10300/include/asm/spinlock.h @@ -26,11 +26,6 @@ #define arch_spin_is_locked(x) (*(volatile signed char *)(&(x)->slock) != 0) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->slock, !VAL); -} - static inline void arch_spin_unlock(arch_spinlock_t *lock) { asm volatile( diff --git a/arch/parisc/include/asm/spinlock.h b/arch/parisc/include/asm/spinlock.h index e32936c..55bfe4a 100644 --- a/arch/parisc/include/asm/spinlock.h +++ b/arch/parisc/include/asm/spinlock.h @@ -14,13 +14,6 @@ static inline int arch_spin_is_locked(arch_spinlock_t *x) #define arch_spin_lock(lock) arch_spin_lock_flags(lock, 0) -static inline void arch_spin_unlock_wait(arch_spinlock_t *x) -{ - volatile unsigned int *a = __ldcw_align(x); - - smp_cond_load_acquire(a, VAL); -} - static inline void arch_spin_lock_flags(arch_spinlock_t *x, unsigned long flags) { diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index 8c1b913..d256e44 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -170,39 +170,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) lock->slock = 0; } -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - arch_spinlock_t lock_val; - - smp_mb(); - - /* - * Atomically load and store back the lock value (unchanged). This - * ensures that our observation of the lock value is ordered with - * respect to other lock operations. - */ - __asm__ __volatile__( -"1: " PPC_LWARX(%0, 0, %2, 0) "\n" -" stwcx. %0, 0, %2\n" -" bne- 1b\n" - : "=&r" (lock_val), "+m" (*lock) - : "r" (lock) - : "cr0", "xer"); - - if (arch_spin_value_unlocked(lock_val)) - goto out; - - while (lock->slock) { - HMT_low(); - if (SHARED_PROCESSOR) - __spin_yield(lock); - } - HMT_medium(); - -out: - smp_mb(); -} - /* * Read-write spinlocks, allowing multiple readers * but only one writer. diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h index f7838ec..217ee52 100644 --- a/arch/s390/include/asm/spinlock.h +++ b/arch/s390/include/asm/spinlock.h @@ -98,13 +98,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lp) : "cc", "memory"); } -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - while (arch_spin_is_locked(lock)) - arch_spin_relax(lock); - smp_acquire__after_ctrl_dep(); -} - /* * Read-write spinlocks, allowing multiple readers * but only one writer. diff --git a/arch/sh/include/asm/spinlock-cas.h b/arch/sh/include/asm/spinlock-cas.h index c46e8cc..5ed7dbb 100644 --- a/arch/sh/include/asm/spinlock-cas.h +++ b/arch/sh/include/asm/spinlock-cas.h @@ -29,11 +29,6 @@ static inline unsigned __sl_cas(volatile unsigned *p, unsigned old, unsigned new #define arch_spin_is_locked(x) ((x)->lock <= 0) #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, VAL > 0); -} - static inline void arch_spin_lock(arch_spinlock_t *lock) { while (!__sl_cas(&lock->lock, 1, 0)); diff --git a/arch/sh/include/asm/spinlock-llsc.h b/arch/sh/include/asm/spinlock-llsc.h index cec7814..f77263a 100644 --- a/arch/sh/include/asm/spinlock-llsc.h +++ b/arch/sh/include/asm/spinlock-llsc.h @@ -21,11 +21,6 @@ #define arch_spin_is_locked(x) ((x)->lock <= 0) #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, VAL > 0); -} - /* * Simple spin lock operations. There are two variants, one clears IRQ's * on the local processor, one does not. diff --git a/arch/sparc/include/asm/spinlock_32.h b/arch/sparc/include/asm/spinlock_32.h index 8011e79..67345b2 100644 --- a/arch/sparc/include/asm/spinlock_32.h +++ b/arch/sparc/include/asm/spinlock_32.h @@ -14,11 +14,6 @@ #define arch_spin_is_locked(lock) (*((volatile unsigned char *)(lock)) != 0) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->lock, !VAL); -} - static inline void arch_spin_lock(arch_spinlock_t *lock) { __asm__ __volatile__( diff --git a/arch/tile/include/asm/spinlock_32.h b/arch/tile/include/asm/spinlock_32.h index b14b1ba..cba8ba9 100644 --- a/arch/tile/include/asm/spinlock_32.h +++ b/arch/tile/include/asm/spinlock_32.h @@ -64,8 +64,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) lock->current_ticket = old_ticket + TICKET_QUANTUM; } -void arch_spin_unlock_wait(arch_spinlock_t *lock); - /* * Read-write spinlocks, allowing multiple readers * but only one writer. diff --git a/arch/tile/include/asm/spinlock_64.h b/arch/tile/include/asm/spinlock_64.h index b9718fb..9a2c2d6 100644 --- a/arch/tile/include/asm/spinlock_64.h +++ b/arch/tile/include/asm/spinlock_64.h @@ -58,8 +58,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) __insn_fetchadd4(&lock->lock, 1U << __ARCH_SPIN_CURRENT_SHIFT); } -void arch_spin_unlock_wait(arch_spinlock_t *lock); - void arch_spin_lock_slow(arch_spinlock_t *lock, u32 val); /* Grab the "next" ticket number and bump it atomically. diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c index 076c6cc..db9333f 100644 --- a/arch/tile/lib/spinlock_32.c +++ b/arch/tile/lib/spinlock_32.c @@ -62,29 +62,6 @@ int arch_spin_trylock(arch_spinlock_t *lock) } EXPORT_SYMBOL(arch_spin_trylock); -void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - u32 iterations = 0; - int curr = READ_ONCE(lock->current_ticket); - int next = READ_ONCE(lock->next_ticket); - - /* Return immediately if unlocked. */ - if (next == curr) - return; - - /* Wait until the current locker has released the lock. */ - do { - delay_backoff(iterations++); - } while (READ_ONCE(lock->current_ticket) == curr); - - /* - * The TILE architecture doesn't do read speculation; therefore - * a control dependency guarantees a LOAD->{LOAD,STORE} order. - */ - barrier(); -} -EXPORT_SYMBOL(arch_spin_unlock_wait); - /* * The low byte is always reserved to be the marker for a "tns" operation * since the low bit is set to "1" by a tns. The next seven bits are diff --git a/arch/tile/lib/spinlock_64.c b/arch/tile/lib/spinlock_64.c index a4b5b2c..de414c2 100644 --- a/arch/tile/lib/spinlock_64.c +++ b/arch/tile/lib/spinlock_64.c @@ -62,28 +62,6 @@ int arch_spin_trylock(arch_spinlock_t *lock) } EXPORT_SYMBOL(arch_spin_trylock); -void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - u32 iterations = 0; - u32 val = READ_ONCE(lock->lock); - u32 curr = arch_spin_current(val); - - /* Return immediately if unlocked. */ - if (arch_spin_next(val) == curr) - return; - - /* Wait until the current locker has released the lock. */ - do { - delay_backoff(iterations++); - } while (arch_spin_current(READ_ONCE(lock->lock)) == curr); - - /* - * The TILE architecture doesn't do read speculation; therefore - * a control dependency guarantees a LOAD->{LOAD,STORE} order. - */ - barrier(); -} -EXPORT_SYMBOL(arch_spin_unlock_wait); /* * If the read lock fails due to a writer, we retry periodically diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h index a36221c..3bb4968 100644 --- a/arch/xtensa/include/asm/spinlock.h +++ b/arch/xtensa/include/asm/spinlock.h @@ -33,11 +33,6 @@ #define arch_spin_is_locked(x) ((x)->slock != 0) -static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) -{ - smp_cond_load_acquire(&lock->slock, !VAL); -} - #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) static inline void arch_spin_lock(arch_spinlock_t *lock)
