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authorTony Luck <tony.luck@intel.com>2009-10-23 17:58:54 -0700
committerTony Luck <tony.luck@intel.com>2009-10-23 17:58:54 -0700
commit48fade6c5a96d29cd3d0e016557a3fd835fd4049 (patch)
tree671554b43c2deed301dfe1a93acaab4766cf6fef /arch/ia64
parentb94b08081fcecf83fa690d6c5664f6316fe72208 (diff)
parent1502f08edc040b6ba4b986454416564088995e79 (diff)
downloadlinux-2.6.38-lt-ux500-48fade6c5a96d29cd3d0e016557a3fd835fd4049.tar.gz
Pull ticket4byte into release branch
Diffstat (limited to 'arch/ia64')
-rw-r--r--arch/ia64/include/asm/spinlock.h62
-rw-r--r--arch/ia64/include/asm/spinlock_types.h2
2 files changed, 42 insertions, 22 deletions
diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h
index 30bb930e111..239ecdc9516 100644
--- a/arch/ia64/include/asm/spinlock.h
+++ b/arch/ia64/include/asm/spinlock.h
@@ -25,61 +25,82 @@
* by atomically noting the tail and incrementing it by one (thus adding
* ourself to the queue and noting our position), then waiting until the head
* becomes equal to the the initial value of the tail.
+ * The pad bits in the middle are used to prevent the next_ticket number
+ * overflowing into the now_serving number.
*
- * 63 32 31 0
+ * 31 17 16 15 14 0
* +----------------------------------------------------+
- * | next_ticket_number | now_serving |
+ * | now_serving | padding | next_ticket |
* +----------------------------------------------------+
*/
-#define TICKET_SHIFT 32
+#define TICKET_SHIFT 17
+#define TICKET_BITS 15
+#define TICKET_MASK ((1 << TICKET_BITS) - 1)
static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock)
{
- int *p = (int *)&lock->lock, turn, now_serving;
+ int *p = (int *)&lock->lock, ticket, serve;
- now_serving = *p;
- turn = ia64_fetchadd(1, p+1, acq);
+ ticket = ia64_fetchadd(1, p, acq);
- if (turn == now_serving)
+ if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
return;
- do {
+ ia64_invala();
+
+ for (;;) {
+ asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(p) : "memory");
+
+ if (!(((serve >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
+ return;
cpu_relax();
- } while (ACCESS_ONCE(*p) != turn);
+ }
}
static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock)
{
- long tmp = ACCESS_ONCE(lock->lock), try;
-
- if (!(((tmp >> TICKET_SHIFT) ^ tmp) & ((1L << TICKET_SHIFT) - 1))) {
- try = tmp + (1L << TICKET_SHIFT);
+ int tmp = ACCESS_ONCE(lock->lock);
- return ia64_cmpxchg(acq, &lock->lock, tmp, try, sizeof (tmp)) == tmp;
- }
+ if (!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK))
+ return ia64_cmpxchg(acq, &lock->lock, tmp, tmp + 1, sizeof (tmp)) == tmp;
return 0;
}
static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock)
{
- int *p = (int *)&lock->lock;
+ unsigned short *p = (unsigned short *)&lock->lock + 1, tmp;
- (void)ia64_fetchadd(1, p, rel);
+ asm volatile ("ld2.bias %0=[%1]" : "=r"(tmp) : "r"(p));
+ ACCESS_ONCE(*p) = (tmp + 2) & ~1;
+}
+
+static __always_inline void __ticket_spin_unlock_wait(raw_spinlock_t *lock)
+{
+ int *p = (int *)&lock->lock, ticket;
+
+ ia64_invala();
+
+ for (;;) {
+ asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory");
+ if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
+ return;
+ cpu_relax();
+ }
}
static inline int __ticket_spin_is_locked(raw_spinlock_t *lock)
{
long tmp = ACCESS_ONCE(lock->lock);
- return !!(((tmp >> TICKET_SHIFT) ^ tmp) & ((1L << TICKET_SHIFT) - 1));
+ return !!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK);
}
static inline int __ticket_spin_is_contended(raw_spinlock_t *lock)
{
long tmp = ACCESS_ONCE(lock->lock);
- return (((tmp >> TICKET_SHIFT) - tmp) & ((1L << TICKET_SHIFT) - 1)) > 1;
+ return ((tmp - (tmp >> TICKET_SHIFT)) & TICKET_MASK) > 1;
}
static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
@@ -116,8 +137,7 @@ static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock,
static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
{
- while (__raw_spin_is_locked(lock))
- cpu_relax();
+ __ticket_spin_unlock_wait(lock);
}
#define __raw_read_can_lock(rw) (*(volatile int *)(rw) >= 0)
diff --git a/arch/ia64/include/asm/spinlock_types.h b/arch/ia64/include/asm/spinlock_types.h
index b61d136d9bc..474e46f1ab4 100644
--- a/arch/ia64/include/asm/spinlock_types.h
+++ b/arch/ia64/include/asm/spinlock_types.h
@@ -6,7 +6,7 @@
#endif
typedef struct {
- volatile unsigned long lock;
+ volatile unsigned int lock;
} raw_spinlock_t;
#define __RAW_SPIN_LOCK_UNLOCKED { 0 }