[PATCH 05/20] x86/ticketlock: make __ticket_spin_lock common
DORMANTno replies
From: Jeremy Fitzhardinge <hidden>
Date: 2010-11-03 14:59:46
Subsystem:
locking primitives, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Linus Torvalds, Thomas Gleixner, Borislav Petkov, Dave Hansen
Revision v1 of 2 in this series.
Revisions (2)
- v1 current
- v1
From: Jeremy Fitzhardinge <redacted> Aside from the particular form of the xadd instruction, they're identical. So factor out the xadd and use common code for the rest. Signed-off-by: Jeremy Fitzhardinge <redacted> --- arch/x86/include/asm/spinlock.h | 42 ++++++++++++++++++-------------------- 1 files changed, 20 insertions(+), 22 deletions(-)
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 7586d7a..4f9fa24 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h@@ -69,13 +69,27 @@ static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) * save some instructions and make the code more elegant. There really isn't * much between them in performance though, especially as locks are out of line. */ -#if (NR_CPUS < 256) -static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) +static __always_inline struct __raw_tickets __ticket_spin_claim(struct arch_spinlock *lock) { - register struct __raw_tickets inc = { .tail = 1 }; + register struct __raw_tickets tickets = { .tail = 1 }; + + if (sizeof(lock->tickets.head) == sizeof(u8)) + asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" + : "+r" (tickets), "+m" (lock->tickets) + : : "memory", "cc"); + else + asm volatile (LOCK_PREFIX "xaddl %0, %1\n" + : "+r" (tickets), "+m" (lock->tickets) + : : "memory", "cc"); - asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" - : "+r" (inc), "+m" (lock->tickets) : : "memory", "cc"); + return tickets; +} + +static __always_inline void __ticket_spin_lock(struct arch_spinlock *lock) +{ + register struct __raw_tickets inc; + + inc = __ticket_spin_claim(lock); for (;;) { if (inc.head == inc.tail)
@@ -86,6 +100,7 @@ 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;
@@ -105,23 +120,6 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) return tmp; } #else -static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) -{ - register struct __raw_tickets inc = { .tickets.tail = 1 }; - - asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t" - : "+r" (inc), "+m" (lock->tickets) - : : "memory", "cc"); - - for (;;) { - if (inc.head == inc.tail) - return; - cpu_relax(); - inc.head = ACCESS_ONCE(lock->tickets.head); - } - barrier(); /* make sure nothing creeps before the lock is taken */ -} - static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) { unsigned tmp;
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1.7.2.3