From 3d94ae0c70a71a9824479366775e2c7679a57d94 Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy@goop.org>
Date: Wed, 28 Sep 2011 11:49:28 -0700
Subject: [PATCH 1/2] x86/cmpxchg: add a locked add() helper
Mostly to remove some conditional code in spinlock.h.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
---
arch/x86/include/asm/cmpxchg.h | 42 +++++++++++++++++++++++++++++++++
arch/x86/include/asm/spinlock.h | 15 +-----------
2 files changed, 43 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index 5d3acdf5a7a68..49eade13161cd 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -14,6 +14,8 @@ extern void __cmpxchg_wrong_size(void)
__compiletime_error("Bad argument size for cmpxchg");
extern void __xadd_wrong_size(void)
__compiletime_error("Bad argument size for xadd");
+extern void __add_wrong_size(void)
+ __compiletime_error("Bad argument size for add");
/*
* Constants for operation sizes. On 32-bit, the 64-bit size it set to
@@ -207,4 +209,44 @@ extern void __xadd_wrong_size(void)
#define xadd_sync(ptr, inc) __xadd((ptr), (inc), "lock; ")
#define xadd_local(ptr, inc) __xadd((ptr), (inc), "")
+#define __add(ptr, inc, lock) \
+ ({ \
+ __typeof__ (*(ptr)) __ret = (inc); \
+ switch (sizeof(*(ptr))) { \
+ case __X86_CASE_B: \
+ asm volatile (lock "addb %b1, %0\n" \
+ : "+m" (*(ptr)) : "ri" (inc) \
+ : "memory", "cc"); \
+ break; \
+ case __X86_CASE_W: \
+ asm volatile (lock "addw %w1, %0\n" \
+ : "+m" (*(ptr)) : "ri" (inc) \
+ : "memory", "cc"); \
+ break; \
+ case __X86_CASE_L: \
+ asm volatile (lock "addl %1, %0\n" \
+ : "+m" (*(ptr)) : "ri" (inc) \
+ : "memory", "cc"); \
+ break; \
+ case __X86_CASE_Q: \
+ asm volatile (lock "addq %1, %0\n" \
+ : "+m" (*(ptr)) : "ri" (inc) \
+ : "memory", "cc"); \
+ break; \
+ default: \
+ __add_wrong_size(); \
+ } \
+ __ret; \
+ })
+
+/*
+ * add_*() adds "inc" to "*ptr"
+ *
+ * __add() takes a lock prefix
+ * add_smp() is locked when multiple CPUs are online
+ * add_sync() is always locked
+ */
+#define add_smp(ptr, inc) __add((ptr), (inc), LOCK_PREFIX)
+#define add_sync(ptr, inc) __add((ptr), (inc), "lock; ")
+
#endif /* ASM_X86_CMPXCHG_H */
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 972c260919a39..a82c2bf504b60 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -79,23 +79,10 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
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)
{
- asm volatile(UNLOCK_LOCK_PREFIX "incb %0"
- : "+m" (lock->head_tail)
- :
- : "memory", "cc");
+ __add(&lock->tickets.head, 1, UNLOCK_LOCK_PREFIX);
}
-#else
-static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
-{
- asm volatile(UNLOCK_LOCK_PREFIX "incw %0"
- : "+m" (lock->head_tail)
- :
- : "memory", "cc");
-}
-#endif
static inline int __ticket_spin_is_locked(arch_spinlock_t *lock)
{
From 31a8394e069e47dc47f4c29e4213aa943342f19f Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy@goop.org>
Date: Fri, 30 Sep 2011 12:14:10 -0700
Subject: [PATCH 2/2] x86: consolidate xchg and xadd macros
They both have a basic "put new value in location, return old value"
pattern, so they can use the same macro easily.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
---
arch/x86/include/asm/cmpxchg.h | 114 +++++++++++----------------------
1 file changed, 36 insertions(+), 78 deletions(-)
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index 49eade13161cd..5488e10b9dba4 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -33,60 +33,47 @@ extern void __add_wrong_size(void)
#define __X86_CASE_Q -1 /* sizeof will never return -1 */
#endif
+/*
+ * An exchange-type operation, which takes a value and a pointer, and
+ * returns a the old value.
+ */
+#define __xchg_op(ptr, arg, op, lock) \
+ ({ \
+ __typeof__ (*(ptr)) __ret = (arg); \
+ switch (sizeof(*(ptr))) { \
+ case __X86_CASE_B: \
+ asm volatile (lock #op "b %b0, %1\n" \
+ : "+r" (__ret), "+m" (*(ptr)) \
+ : : "memory", "cc"); \
+ break; \
+ case __X86_CASE_W: \
+ asm volatile (lock #op "w %w0, %1\n" \
+ : "+r" (__ret), "+m" (*(ptr)) \
+ : : "memory", "cc"); \
+ break; \
+ case __X86_CASE_L: \
+ asm volatile (lock #op "l %0, %1\n" \
+ : "+r" (__ret), "+m" (*(ptr)) \
+ : : "memory", "cc"); \
+ break; \
+ case __X86_CASE_Q: \
+ asm volatile (lock #op "q %q0, %1\n" \
+ : "+r" (__ret), "+m" (*(ptr)) \
+ : : "memory", "cc"); \
+ break; \
+ default: \
+ __ ## op ## _wrong_size(); \
+ } \
+ __ret; \
+ })
+
/*
* Note: no "lock" prefix even on SMP: xchg always implies lock anyway.
* Since this is generally used to protect other memory information, we
* use "asm volatile" and "memory" clobbers to prevent gcc from moving
* information around.
*/
-#define __xchg(x, ptr, size) \
-({ \
- __typeof(*(ptr)) __x = (x); \
- switch (size) { \
- case __X86_CASE_B: \
- { \
- volatile u8 *__ptr = (volatile u8 *)(ptr); \
- asm volatile("xchgb %0,%1" \
- : "=q" (__x), "+m" (*__ptr) \
- : "0" (__x) \
- : "memory"); \
- break; \
- } \
- case __X86_CASE_W: \
- { \
- volatile u16 *__ptr = (volatile u16 *)(ptr); \
- asm volatile("xchgw %0,%1" \
- : "=r" (__x), "+m" (*__ptr) \
- : "0" (__x) \
- : "memory"); \
- break; \
- } \
- case __X86_CASE_L: \
- { \
- volatile u32 *__ptr = (volatile u32 *)(ptr); \
- asm volatile("xchgl %0,%1" \
- : "=r" (__x), "+m" (*__ptr) \
- : "0" (__x) \
- : "memory"); \
- break; \
- } \
- case __X86_CASE_Q: \
- { \
- volatile u64 *__ptr = (volatile u64 *)(ptr); \
- asm volatile("xchgq %0,%1" \
- : "=r" (__x), "+m" (*__ptr) \
- : "0" (__x) \
- : "memory"); \
- break; \
- } \
- default: \
- __xchg_wrong_size(); \
- } \
- __x; \
-})
-
-#define xchg(ptr, v) \
- __xchg((v), (ptr), sizeof(*ptr))
+#define xchg(ptr, v) __xchg_op((ptr), (v), xchg, "")
/*
* Atomic compare and exchange. Compare OLD with MEM, if identical,
@@ -167,36 +154,6 @@ extern void __add_wrong_size(void)
__cmpxchg_local((ptr), (old), (new), sizeof(*ptr))
#endif
-#define __xadd(ptr, inc, lock) \
- ({ \
- __typeof__ (*(ptr)) __ret = (inc); \
- switch (sizeof(*(ptr))) { \
- case __X86_CASE_B: \
- asm volatile (lock "xaddb %b0, %1\n" \
- : "+r" (__ret), "+m" (*(ptr)) \
- : : "memory", "cc"); \
- break; \
- case __X86_CASE_W: \
- asm volatile (lock "xaddw %w0, %1\n" \
- : "+r" (__ret), "+m" (*(ptr)) \
- : : "memory", "cc"); \
- break; \
- case __X86_CASE_L: \
- asm volatile (lock "xaddl %0, %1\n" \
- : "+r" (__ret), "+m" (*(ptr)) \
- : : "memory", "cc"); \
- break; \
- case __X86_CASE_Q: \
- asm volatile (lock "xaddq %q0, %1\n" \
- : "+r" (__ret), "+m" (*(ptr)) \
- : : "memory", "cc"); \
- break; \
- default: \
- __xadd_wrong_size(); \
- } \
- __ret; \
- })
-
/*
* xadd() adds "inc" to "*ptr" and atomically returns the previous
* value of "*ptr".
@@ -205,6 +162,7 @@ extern void __add_wrong_size(void)
* xadd_sync() is always locked
* xadd_local() is never locked
*/
+#define __xadd(ptr, inc, lock) __xchg_op((ptr), (inc), xadd, lock)
#define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX)
#define xadd_sync(ptr, inc) __xadd((ptr), (inc), "lock; ")
#define xadd_local(ptr, inc) __xadd((ptr), (inc), "")