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x86, ticketlock: Make __ticket_spin_trylock common

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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>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Jeremy Fitzhardinge
2010-07-13 15:14:26 -07:00
committed by H. Peter Anvin
parent 2994488fe5
commit 229855d6f3
2 changed files with 15 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

49
arch/x86/include/asm/spinlock.h
View File

@@ -69,60 +69,33 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
barrier(); /* make sure nothing creeps before the lock is taken */ 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) static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
{ {
unsigned int tmp, new; arch_spinlock_t old, new;
asm volatile("movzwl %2, %0\n\t" old.tickets = ACCESS_ONCE(lock->tickets);
"cmpb %h0,%b0\n\t" if (old.tickets.head != old.tickets.tail)
"leal 0x100(%" REG_PTR_MODE "0), %1\n\t" return 0;
"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");
return tmp; new.head_tail = old.head_tail + (1 << TICKET_SHIFT);
/* cmpxchg is a full barrier, so nothing can move before it */
return cmpxchg(&lock->head_tail, old.head_tail, new.head_tail) == old.head_tail;
} }
#if (NR_CPUS < 256)
static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
{ {
asm volatile(UNLOCK_LOCK_PREFIX "incb %0" asm volatile(UNLOCK_LOCK_PREFIX "incb %0"
: "+m" (lock->slock) : "+m" (lock->head_tail)
: :
: "memory", "cc"); : "memory", "cc");
} }
#else #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) static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
{ {
asm volatile(UNLOCK_LOCK_PREFIX "incw %0" asm volatile(UNLOCK_LOCK_PREFIX "incw %0"
: "+m" (lock->slock) : "+m" (lock->head_tail)
: :
: "memory", "cc"); : "memory", "cc");
} }

6
arch/x86/include/asm/spinlock_types.h
View File

@@ -9,8 +9,10 @@
#if (CONFIG_NR_CPUS < 256) #if (CONFIG_NR_CPUS < 256)
typedef u8 __ticket_t; typedef u8 __ticket_t;
typedef u16 __ticketpair_t;
#else #else
typedef u16 __ticket_t; typedef u16 __ticket_t;
typedef u32 __ticketpair_t;
#endif #endif
#define TICKET_SHIFT (sizeof(__ticket_t) * 8) #define TICKET_SHIFT (sizeof(__ticket_t) * 8)
@@ -18,14 +20,14 @@ typedef u16 __ticket_t;
typedef struct arch_spinlock { typedef struct arch_spinlock {
union { union {
unsigned int slock; __ticketpair_t head_tail;
struct __raw_tickets { struct __raw_tickets {
__ticket_t head, tail; __ticket_t head, tail;
} tickets; } tickets;
}; };
} arch_spinlock_t; } arch_spinlock_t;
#define __ARCH_SPIN_LOCK_UNLOCKED { { .slock = 0 } } #define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } }
#include <asm/rwlock.h> #include <asm/rwlock.h>