[PATCH] atomic: inc_not_zero

Introduce an atomic_inc_not_zero operation.  Make this a special case of
atomic_add_unless because lockless pagecache actually wants
atomic_inc_not_negativeone due to its offset refcount.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt
index f1744161ef0694cef8dab811d25e0efea9c1ea7a..23a1c2402bccf3ec6d8bbf97bba3becfcf149272 100644 (file)
--- a/Documentation/atomic_ops.txt
+++ b/Documentation/atomic_ops.txt
@@ -115,7 +115,7 @@ boolean is return which indicates whether the resulting counter value
 is negative.  It requires explicit memory barrier semantics around the
 operation.
 
-Finally:
+Then:
 
        int atomic_cmpxchg(atomic_t *v, int old, int new);
 
@@ -129,6 +129,18 @@ atomic_cmpxchg requires explicit memory barriers around the operation.
 The semantics for atomic_cmpxchg are the same as those defined for 'cas'
 below.
 
+Finally:
+
+       int atomic_add_unless(atomic_t *v, int a, int u);
+
+If the atomic value v is not equal to u, this function adds a to v, and
+returns non zero. If v is equal to u then it returns zero. This is done as
+an atomic operation.
+
+atomic_add_unless requires explicit memory barriers around the operation.
+
+atomic_inc_not_zero, equivalent to atomic_add_unless(v, 1, 0)
+
 
 If a caller requires memory barrier semantics around an atomic_t
 operation which does not return a value, a set of interfaces are

diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index be46f65451846af2eef721a0c1d111082cbeec86..cb3cf0f228221154a2dd5e658b8550733a966866 100644 (file)
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -53,6 +53,21 @@ int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       spin_lock_irqsave(ATOMIC_HASH(v), flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
+       return ret != u;
+}
+
+static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
+/* Atomic operations are already serializing */
 void atomic_set(atomic_t *v, int i)
 {
        unsigned long flags;

diff --git a/include/asm-alpha/atomic.h b/include/asm-alpha/atomic.h
index a6660809a879c99c14b2d935a2fe941ff48bdc96..36505bb4e8cbb8790e4be3d44b067f44e3ede462 100644 (file)
--- a/include/asm-alpha/atomic.h
+++ b/include/asm-alpha/atomic.h
@@ -179,6 +179,16 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t * v)
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_dec_return(v) atomic_sub_return(1,(v))
 #define atomic64_dec_return(v) atomic64_sub_return(1,(v))
 

diff --git a/include/asm-arm/atomic.h b/include/asm-arm/atomic.h
index 8ab1689ef56a1c3388fd0d25801230fd3b6516e7..75b802719723ad459d719b6f598254fe0dfe02e4 100644 (file)
--- a/include/asm-arm/atomic.h
+++ b/include/asm-arm/atomic.h
@@ -173,6 +173,17 @@ static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 
 #endif /* __LINUX_ARM_ARCH__ */
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int c, old;
+
+       c = atomic_read(v);
+       while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
+               c = old;
+       return c != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_add(i, v)       (void) atomic_add_return(i, v)
 #define atomic_inc(v)          (void) atomic_add_return(1, v)
 #define atomic_sub(i, v)       (void) atomic_sub_return(i, v)

diff --git a/include/asm-arm26/atomic.h b/include/asm-arm26/atomic.h
index 54b24ead7132520692d54ea45eec9329780b3e12..a47cadc59686237260877f1874b2c18ff0ed9421 100644 (file)
--- a/include/asm-arm26/atomic.h
+++ b/include/asm-arm26/atomic.h
@@ -76,6 +76,21 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       local_irq_restore(flags);
+
+       return ret != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 {
         unsigned long flags;

diff --git a/include/asm-cris/atomic.h b/include/asm-cris/atomic.h
index 45891f7de00fc1c58a9bcc48158c75dc2a386746..683b05a57d88068527bea8d99343c2425503318c 100644 (file)
--- a/include/asm-cris/atomic.h
+++ b/include/asm-cris/atomic.h
@@ -136,6 +136,20 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       cris_atomic_save(v, flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       cris_atomic_restore(v, flags);
+       return ret != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 /* Atomic operations are already serializing */
 #define smp_mb__before_atomic_dec()    barrier()
 #define smp_mb__after_atomic_dec()     barrier()

diff --git a/include/asm-frv/atomic.h b/include/asm-frv/atomic.h
index 55f06a0e949f57046869dc0174ea6fb2d25441a7..f6539ff569c5278abece2c6442cbab205dd80311 100644 (file)
--- a/include/asm-frv/atomic.h
+++ b/include/asm-frv/atomic.h
@@ -416,4 +416,14 @@ extern uint32_t __cmpxchg_32(uint32_t *v, uint32_t test, uint32_t new);
 
 #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #endif /* _ASM_ATOMIC_H */

diff --git a/include/asm-h8300/atomic.h b/include/asm-h8300/atomic.h
index d504392594919e3389918ab8210c84eb520bc0e2..f23d86819ea82b83fb75bcce32516b78817524e0 100644 (file)
--- a/include/asm-h8300/atomic.h
+++ b/include/asm-h8300/atomic.h
@@ -95,6 +95,20 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       local_irq_restore(flags);
+       return ret != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 static __inline__ void atomic_clear_mask(unsigned long mask, unsigned long *v)
 {
        __asm__ __volatile__("stc ccr,r1l\n\t"

diff --git a/include/asm-i386/atomic.h b/include/asm-i386/atomic.h
index 5ff698e9d2c2f79738fe5d2de237320138bf7f3c..c68557aa04b2b0ef9246086f6d52b156c72966c0 100644 (file)
--- a/include/asm-i386/atomic.h
+++ b/include/asm-i386/atomic.h
@@ -217,6 +217,25 @@ static __inline__ int atomic_sub_return(int i, atomic_t *v)
 
 #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
 
+/**
+ * atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_inc_return(v)  (atomic_add_return(1,v))
 #define atomic_dec_return(v)  (atomic_sub_return(1,v))
 

diff --git a/include/asm-ia64/atomic.h b/include/asm-ia64/atomic.h
index 593d3da9f3c20f6a03e96165fd8395e465497e24..2fbebf85c31d55a1b1ac8b5f7d69a62f5c554860 100644 (file)
--- a/include/asm-ia64/atomic.h
+++ b/include/asm-ia64/atomic.h
@@ -90,6 +90,16 @@ ia64_atomic64_sub (__s64 i, atomic64_t *v)
 
 #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_add_return(i,v)                                         \
 ({                                                                     \
        int __ia64_aar_i = (i);                                         \

diff --git a/include/asm-m68k/atomic.h b/include/asm-m68k/atomic.h
index b821975a361a1e7af8caba44d56ffb29d8a0083a..e3c962eeabf3d37871d24e87638fcc8005bf3048 100644 (file)
--- a/include/asm-m68k/atomic.h
+++ b/include/asm-m68k/atomic.h
@@ -141,6 +141,16 @@ static inline void atomic_set_mask(unsigned long mask, unsigned long *v)
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 /* Atomic operations are already serializing */
 #define smp_mb__before_atomic_dec()    barrier()
 #define smp_mb__after_atomic_dec()     barrier()

diff --git a/include/asm-m68knommu/atomic.h b/include/asm-m68knommu/atomic.h
index 2fd33a56b603a2bc63e93c26bbb94801d7b3dd14..3c1cc153c4154c233fc05dc6f0f0b8f7f3b8e9f9 100644 (file)
--- a/include/asm-m68knommu/atomic.h
+++ b/include/asm-m68knommu/atomic.h
@@ -130,6 +130,16 @@ static inline int atomic_sub_return(int i, atomic_t * v)
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_dec_return(v) atomic_sub_return(1,(v))
 #define atomic_inc_return(v) atomic_add_return(1,(v))
 

diff --git a/include/asm-mips/atomic.h b/include/asm-mips/atomic.h
index 4fba0d003c995b1b8c4ed3313a6b8d715c1b073c..2c87b41e69baa60019143bfed35550fc13fc6e2f 100644 (file)
--- a/include/asm-mips/atomic.h
+++ b/include/asm-mips/atomic.h
@@ -289,6 +289,25 @@ static __inline__ int atomic_sub_if_positive(int i, atomic_t * v)
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+/**
+ * atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_dec_return(v) atomic_sub_return(1,(v))
 #define atomic_inc_return(v) atomic_add_return(1,(v))
 

diff --git a/include/asm-parisc/atomic.h b/include/asm-parisc/atomic.h
index 52c9a45b5f871211bfd4aa7bc28f65be82735ffe..983e9a2b6042858b492d8dbde8b97b9d5f96b701 100644 (file)
--- a/include/asm-parisc/atomic.h
+++ b/include/asm-parisc/atomic.h
@@ -166,6 +166,25 @@ static __inline__ int atomic_read(const atomic_t *v)
 /* exported interface */
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+/**
+ * atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_add(i,v)        ((void)(__atomic_add_return( ((int)i),(v))))
 #define atomic_sub(i,v)        ((void)(__atomic_add_return(-((int)i),(v))))
 #define atomic_inc(v)  ((void)(__atomic_add_return(   1,(v))))

diff --git a/include/asm-powerpc/atomic.h b/include/asm-powerpc/atomic.h
index 37205faa9d7c7a872f4a711ee3b162ec1858ab6d..ec4b14468959e295dc29ebbd0b212b6899597f70 100644 (file)
--- a/include/asm-powerpc/atomic.h
+++ b/include/asm-powerpc/atomic.h
@@ -166,6 +166,31 @@ static __inline__ int atomic_dec_return(atomic_t *v)
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+/**
+ * atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic_add_unless(v, a, u)                                                      \
+({                                                                                                                      \
+          int c, old;                                                                                   \
+          c = atomic_read(v);                                                                   \
+          for (;;) {                                                                                     \
+                          if (unlikely(c == (u)))                                               \
+                                          break;                                                                 \
+                          old = atomic_cmpxchg((v), c, c + (a));                 \
+                          if (likely(old == c))                                                   \
+                                          break;                                                                 \
+                          c = old;                                                                             \
+          }                                                                                                       \
+          c != (u);                                                                                       \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_sub_and_test(a, v)      (atomic_sub_return((a), (v)) == 0)
 #define atomic_dec_and_test(v)         (atomic_dec_return((v)) == 0)
 

diff --git a/include/asm-s390/atomic.h b/include/asm-s390/atomic.h
index 631014d5de9084ba843454ee136f4288703e452d..b3bd4f679f727d2c3bc24293d845e6f6166ff471 100644 (file)
--- a/include/asm-s390/atomic.h
+++ b/include/asm-s390/atomic.h
@@ -200,6 +200,16 @@ atomic_compare_and_swap(int expected_oldval,int new_val,atomic_t *v)
 
 #define atomic_cmpxchg(v, o, n) (atomic_compare_and_swap((o), (n), &((v)->counter)))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define smp_mb__before_atomic_dec()    smp_mb()
 #define smp_mb__after_atomic_dec()     smp_mb()
 #define smp_mb__before_atomic_inc()    smp_mb()

diff --git a/include/asm-sh/atomic.h b/include/asm-sh/atomic.h
index a148c762d3666567b70528c102c58152cabf0ca2..aabfd334462c178bbba76327a86a48a1efef70ab 100644 (file)
--- a/include/asm-sh/atomic.h
+++ b/include/asm-sh/atomic.h
@@ -101,6 +101,21 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       local_irq_restore(flags);
+
+       return ret != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 static __inline__ void atomic_clear_mask(unsigned int mask, atomic_t *v)
 {
        unsigned long flags;

diff --git a/include/asm-sh64/atomic.h b/include/asm-sh64/atomic.h
index 6eeb57b015ce50442cd5b3c17dad2e21d022980f..927a2bc27b3086140bea65c7345f49b2f97bd995 100644 (file)
--- a/include/asm-sh64/atomic.h
+++ b/include/asm-sh64/atomic.h
@@ -113,6 +113,21 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       local_irq_restore(flags);
+
+       return ret != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 static __inline__ void atomic_clear_mask(unsigned int mask, atomic_t *v)
 {
        unsigned long flags;

diff --git a/include/asm-sparc/atomic.h b/include/asm-sparc/atomic.h
index 52bdd1a895faaf0df90d57d42ec0140cdb5f45b8..62bec7ad271c496e81a8f2d95d4f4377cb16c952 100644 (file)
--- a/include/asm-sparc/atomic.h
+++ b/include/asm-sparc/atomic.h
@@ -20,6 +20,7 @@ typedef struct { volatile int counter; } atomic_t;
 
 extern int __atomic_add_return(int, atomic_t *);
 extern int atomic_cmpxchg(atomic_t *, int, int);
+extern int atomic_add_unless(atomic_t *, int, int);
 extern void atomic_set(atomic_t *, int);
 
 #define atomic_read(v)          ((v)->counter)
@@ -49,6 +50,8 @@ extern void atomic_set(atomic_t *, int);
 #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
 
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 /* This is the old 24-bit implementation.  It's still used internally
  * by some sparc-specific code, notably the semaphore implementation.
  */

diff --git a/include/asm-sparc64/atomic.h b/include/asm-sparc64/atomic.h
index 3a0b4383bbaca3147e97712dd896366b09c8ed0f..8198c3d0d0074368b0d9fbba5d72969b403c4884 100644 (file)
--- a/include/asm-sparc64/atomic.h
+++ b/include/asm-sparc64/atomic.h
@@ -72,6 +72,16 @@ extern int atomic64_sub_ret(int, atomic64_t *);
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 /* Atomic operations are already serializing */
 #ifdef CONFIG_SMP
 #define smp_mb__before_atomic_dec()    membar_storeload_loadload();

diff --git a/include/asm-v850/atomic.h b/include/asm-v850/atomic.h
index e497166ca42b0946c5b5aa406c936ed8c3ab4acf..bede3172ce7f7e999e202fde6b04d31a6e281478 100644 (file)
--- a/include/asm-v850/atomic.h
+++ b/include/asm-v850/atomic.h
@@ -104,6 +104,22 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
        return ret;
 }
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int ret;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       ret = v->counter;
+       if (ret != u)
+               v->counter += a;
+       local_irq_restore(flags);
+
+       return ret != u;
+}
+
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 /* Atomic operations are already serializing on ARM */
 #define smp_mb__before_atomic_dec()    barrier()
 #define smp_mb__after_atomic_dec()     barrier()

diff --git a/include/asm-x86_64/atomic.h b/include/asm-x86_64/atomic.h
index 75c8a1e96737adb4acc3ada66ce0acce8bb476d0..0866ef67f198d8380a8241727ea21f0a16a19ec1 100644 (file)
--- a/include/asm-x86_64/atomic.h
+++ b/include/asm-x86_64/atomic.h
@@ -362,6 +362,25 @@ static __inline__ int atomic_sub_return(int i, atomic_t *v)
 
 #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
 
+/**
+ * atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_inc_return(v)  (atomic_add_return(1,v))
 #define atomic_dec_return(v)  (atomic_sub_return(1,v))
 

diff --git a/include/asm-xtensa/atomic.h b/include/asm-xtensa/atomic.h
index cd40c5e75160302e3e75d3af55febf513a3c04e2..3670cc7695dad79d3326323e8c974abf417851f6 100644 (file)
--- a/include/asm-xtensa/atomic.h
+++ b/include/asm-xtensa/atomic.h
@@ -225,6 +225,25 @@ static inline int atomic_sub_return(int i, atomic_t * v)
 
 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
 
+/**
+ * atomic_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define atomic_add_unless(v, a, u)                             \
+({                                                             \
+       int c, old;                                             \
+       c = atomic_read(v);                                     \
+       while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
+               c = old;                                        \
+       c != (u);                                               \
+})
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
 {
     unsigned int all_f = -1;