Messages in this thread Patch in this message | | | From | Jeremy Fitzhardinge <> | Subject | [PATCH 12/12] x86/ticketlock: make __ticket_spin_trylock common | Date | Wed, 24 Aug 2011 14:37:09 -0700 |
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From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Make trylock code common regardless of ticket size.
(Also, rename arch_spinlock.slock to head_tail.)
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> --- arch/x86/include/asm/spinlock.h | 51 ++++++++------------------------- arch/x86/include/asm/spinlock_types.h | 6 ++- 2 files changed, 16 insertions(+), 41 deletions(-)
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index adf010a..69f96d2 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -70,60 +70,33 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) barrier(); /* make sure nothing creeps before the lock is taken */ } -#if (NR_CPUS < 256) static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) { - unsigned int tmp, new; - - asm volatile("movzwl %2, %0\n\t" - "cmpb %h0,%b0\n\t" - "leal 0x100(%" REG_PTR_MODE "0), %1\n\t" - "jne 1f\n\t" - LOCK_PREFIX "cmpxchgw %w1,%2\n\t" - "1:" - "sete %b1\n\t" - "movzbl %b1,%0\n\t" - : "=&a" (tmp), "=&q" (new), "+m" (lock->slock) - : - : "memory", "cc"); + arch_spinlock_t old, new; + + old.tickets = ACCESS_ONCE(lock->tickets); + if (old.tickets.head != old.tickets.tail) + return 0; - return tmp; + new.head_tail = old.head_tail + (1 << TICKET_SHIFT); + + /* cmpxchg is a full barrier, so nothing can move before it */ + return cmpxchg_flag(&lock->head_tail, old.head_tail, new.head_tail); } +#if (NR_CPUS < 256) static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) { asm volatile(UNLOCK_LOCK_PREFIX "incb %0" - : "+m" (lock->slock) + : "+m" (lock->head_tail) : : "memory", "cc"); } #else -static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) -{ - unsigned tmp; - unsigned new; - - asm volatile("movl %2,%0\n\t" - "movl %0,%1\n\t" - "roll $16, %0\n\t" - "cmpl %0,%1\n\t" - "leal 0x00010000(%" REG_PTR_MODE "0), %1\n\t" - "jne 1f\n\t" - LOCK_PREFIX "cmpxchgl %1,%2\n\t" - "1:" - "sete %b1\n\t" - "movzbl %b1,%0\n\t" - : "=&a" (tmp), "=&q" (new), "+m" (lock->slock) - : - : "memory", "cc"); - - return tmp; -} - static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) { asm volatile(UNLOCK_LOCK_PREFIX "incw %0" - : "+m" (lock->slock) + : "+m" (lock->head_tail) : : "memory", "cc"); } diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h index e3ad1e3..72e154e 100644 --- a/arch/x86/include/asm/spinlock_types.h +++ b/arch/x86/include/asm/spinlock_types.h @@ -9,8 +9,10 @@ #if (CONFIG_NR_CPUS < 256) typedef u8 __ticket_t; +typedef u16 __ticketpair_t; #else typedef u16 __ticket_t; +typedef u32 __ticketpair_t; #endif #define TICKET_SHIFT (sizeof(__ticket_t) * 8) @@ -18,14 +20,14 @@ typedef u16 __ticket_t; typedef struct arch_spinlock { union { - unsigned int slock; + __ticketpair_t head_tail; struct __raw_tickets { __ticket_t head, tail; } tickets; }; } arch_spinlock_t; -#define __ARCH_SPIN_LOCK_UNLOCKED { { .slock = 0 } } +#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } } typedef struct { unsigned int lock; -- 1.7.6
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