diff options
| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2010-07-03 00:26:36 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2011-08-29 22:45:19 +0200 |
| commit | 84eb950db13ca40a0572ce9957e14723500943d6 (patch) | |
| tree | f2912697d8dbaade7fb1a948a6ba439a501fc03a /arch/x86/include/asm/spinlock.h | |
| parent | x86: Use xadd helper more widely (diff) | |
| download | linux-84eb950db13ca40a0572ce9957e14723500943d6.tar.xz linux-84eb950db13ca40a0572ce9957e14723500943d6.zip | |
x86, ticketlock: Clean up types and accessors
A few cleanups to the way spinlocks are defined and accessed:
- define __ticket_t which is the size of a spinlock ticket (ie, enough
bits to hold all the cpus)
- Define struct arch_spinlock as a union containing plain slock and
the head and tail tickets
- Use head and tail to implement some of the spinlock predicates.
- Make all ticket variables unsigned.
- Use TICKET_SHIFT to form constants
Most of this will be used in later patches.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/include/asm/spinlock.h')
| -rw-r--r-- | arch/x86/include/asm/spinlock.h | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index ee67edf86fdd..ea2a04f69ca9 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -55,11 +55,9 @@ * much between them in performance though, especially as locks are out of line. */ #if (NR_CPUS < 256) -#define TICKET_SHIFT 8 - static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { - short inc = 0x0100; + unsigned short inc = 1 << TICKET_SHIFT; asm volatile ( LOCK_PREFIX "xaddw %w0, %1\n" @@ -78,7 +76,7 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) { - int tmp, new; + unsigned int tmp, new; asm volatile("movzwl %2, %0\n\t" "cmpb %h0,%b0\n\t" @@ -103,12 +101,10 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) : "memory", "cc"); } #else -#define TICKET_SHIFT 16 - static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { - int inc = 0x00010000; - int tmp; + unsigned inc = 1 << TICKET_SHIFT; + unsigned tmp; asm volatile(LOCK_PREFIX "xaddl %0, %1\n" "movzwl %w0, %2\n\t" @@ -128,8 +124,8 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) { - int tmp; - int new; + unsigned tmp; + unsigned new; asm volatile("movl %2,%0\n\t" "movl %0,%1\n\t" @@ -159,16 +155,16 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) static inline int __ticket_spin_is_locked(arch_spinlock_t *lock) { - int tmp = ACCESS_ONCE(lock->slock); + struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); - return !!(((tmp >> TICKET_SHIFT) ^ tmp) & ((1 << TICKET_SHIFT) - 1)); + return !!(tmp.tail ^ tmp.head); } static inline int __ticket_spin_is_contended(arch_spinlock_t *lock) { - int tmp = ACCESS_ONCE(lock->slock); + struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets); - return (((tmp >> TICKET_SHIFT) - tmp) & ((1 << TICKET_SHIFT) - 1)) > 1; + return ((tmp.tail - tmp.head) & TICKET_MASK) > 1; } #ifndef CONFIG_PARAVIRT_SPINLOCKS |