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yaml
---
r: 269552
b: refs/heads/master
c: 2994488
h: refs/heads/master
v: v3
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Jeremy Fitzhardinge authored and H. Peter Anvin committed Aug 29, 2011
1 parent 807e712 commit e5b62c4
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Showing 2 changed files with 6 additions and 31 deletions.
2 changes: 1 addition & 1 deletion [refs]
Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: c576a3ea905c25d50339503e0e5c7fef724e0147
refs/heads/master: 2994488fe5bb721de1ded53af1a2fc41f47f6ddc
35 changes: 5 additions & 30 deletions trunk/arch/x86/include/asm/spinlock.h
Original file line number Diff line number Diff line change
Expand Up @@ -54,26 +54,22 @@
* 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)
{
register union {
struct __raw_tickets tickets;
unsigned short slock;
} inc = { .slock = 1 << TICKET_SHIFT };
register struct __raw_tickets inc = { .tail = 1 };

asm volatile (LOCK_PREFIX "xaddw %w0, %1\n"
: "+Q" (inc), "+m" (lock->slock) : : "memory", "cc");
inc = xadd(&lock->tickets, inc);

for (;;) {
if (inc.tickets.head == inc.tickets.tail)
if (inc.head == inc.tail)
break;
cpu_relax();
inc.tickets.head = ACCESS_ONCE(lock->tickets.head);
inc.head = ACCESS_ONCE(lock->tickets.head);
}
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;
Expand Down Expand Up @@ -101,27 +97,6 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
: "memory", "cc");
}
#else
static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
{
unsigned inc = 1 << TICKET_SHIFT;
__ticket_t tmp;

asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t"
: "+r" (inc), "+m" (lock->slock)
: : "memory", "cc");

tmp = inc;
inc >>= TICKET_SHIFT;

for (;;) {
if ((__ticket_t)inc == tmp)
break;
cpu_relax();
tmp = 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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