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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2010-07-02 23:26:36 +0100
committerH. Peter Anvin <hpa@linux.intel.com>2011-08-29 13:45:19 -0700
commit84eb950db13ca40a0572ce9957e14723500943d6 (patch)
treef2912697d8dbaade7fb1a948a6ba439a501fc03a
parent8b8bc2f7311c3223213dbe346d9cc2e299fdb5eb (diff)
downloadlinaro-lsk-84eb950db13ca40a0572ce9957e14723500943d6.tar.gz
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>
-rw-r--r--arch/x86/include/asm/spinlock.h24
-rw-r--r--arch/x86/include/asm/spinlock_types.h20
2 files changed, 28 insertions, 16 deletions
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index ee67edf86fd..ea2a04f69ca 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
diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
index 7c7a486fcb6..1c51bd231e4 100644
--- a/arch/x86/include/asm/spinlock_types.h
+++ b/arch/x86/include/asm/spinlock_types.h
@@ -5,11 +5,27 @@
# error "please don't include this file directly"
#endif
+#include <linux/types.h>
+
+#if (CONFIG_NR_CPUS < 256)
+typedef u8 __ticket_t;
+#else
+typedef u16 __ticket_t;
+#endif
+
+#define TICKET_SHIFT (sizeof(__ticket_t) * 8)
+#define TICKET_MASK ((__ticket_t)((1 << TICKET_SHIFT) - 1))
+
typedef struct arch_spinlock {
- unsigned int slock;
+ union {
+ unsigned int slock;
+ struct __raw_tickets {
+ __ticket_t head, tail;
+ } tickets;
+ };
} arch_spinlock_t;
-#define __ARCH_SPIN_LOCK_UNLOCKED { 0 }
+#define __ARCH_SPIN_LOCK_UNLOCKED { { .slock = 0 } }
#include <asm/rwlock.h>