From 560cb12a4080a48b84da8b96878cafbd193c4d64 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 23 Apr 2014 16:12:30 +0200 Subject: locking,arch: Rewrite generic atomic support Rewrite generic atomic support to only require cmpxchg(), generate all other primitives from that. Furthermore reduce the endless repetition for all these primitives to a few CPP macros. This way we get more for less lines. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140508135852.940119622@infradead.org Cc: Arnd Bergmann Cc: David Howells Cc: Paul E. McKenney Cc: David S. Miller Cc: Linus Torvalds Cc: linux-arch@vger.kernel.org Signed-off-by: Ingo Molnar --- include/asm-generic/atomic.h | 192 ++++++++++++++++++++--------------------- include/asm-generic/atomic64.h | 20 ++++- 2 files changed, 112 insertions(+), 100 deletions(-) (limited to 'include') diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h index 9c79e7603459..56d4d36e1531 100644 --- a/include/asm-generic/atomic.h +++ b/include/asm-generic/atomic.h @@ -18,14 +18,100 @@ #include #include +/* + * atomic_$op() - $op integer to atomic variable + * @i: integer value to $op + * @v: pointer to the atomic variable + * + * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use + * smp_mb__{before,after}_atomic(). + */ + +/* + * atomic_$op_return() - $op interer to atomic variable and returns the result + * @i: integer value to $op + * @v: pointer to the atomic variable + * + * Atomically $ops @i to @v. Does imply a full memory barrier. + */ + #ifdef CONFIG_SMP -/* Force people to define core atomics */ -# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \ - !defined(atomic_clear_mask) || !defined(atomic_set_mask) -# error "SMP requires a little arch-specific magic" -# endif + +/* we can build all atomic primitives from cmpxchg */ + +#define ATOMIC_OP(op, c_op) \ +static inline void atomic_##op(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ +} + +#define ATOMIC_OP_RETURN(op, c_op) \ +static inline int atomic_##op##_return(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ + \ + return c c_op i; \ +} + +#else + +#include + +#define ATOMIC_OP(op, c_op) \ +static inline void atomic_##op(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + \ + raw_local_irq_save(flags); \ + v->counter = v->counter c_op i; \ + raw_local_irq_restore(flags); \ +} + +#define ATOMIC_OP_RETURN(op, c_op) \ +static inline int atomic_##op##_return(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + int ret; \ + \ + raw_local_irq_save(flags); \ + ret = (v->counter = v->counter c_op i); \ + raw_local_irq_restore(flags); \ + \ + return ret; \ +} + +#endif /* CONFIG_SMP */ + +#ifndef atomic_add_return +ATOMIC_OP_RETURN(add, +) +#endif + +#ifndef atomic_sub_return +ATOMIC_OP_RETURN(sub, -) +#endif + +#ifndef atomic_clear_mask +ATOMIC_OP(and, &) +#define atomic_clear_mask(i, v) atomic_and(~(i), (v)) #endif +#ifndef atomic_set_mask +#define CONFIG_ARCH_HAS_ATOMIC_OR +ATOMIC_OP(or, |) +#define atomic_set_mask(i, v) atomic_or((i), (v)) +#endif + +#undef ATOMIC_OP_RETURN +#undef ATOMIC_OP + /* * Atomic operations that C can't guarantee us. Useful for * resource counting etc.. @@ -33,8 +119,6 @@ #define ATOMIC_INIT(i) { (i) } -#ifdef __KERNEL__ - /** * atomic_read - read atomic variable * @v: pointer of type atomic_t @@ -56,52 +140,6 @@ #include -/** - * atomic_add_return - add integer to atomic variable - * @i: integer value to add - * @v: pointer of type atomic_t - * - * Atomically adds @i to @v and returns the result - */ -#ifndef atomic_add_return -static inline int atomic_add_return(int i, atomic_t *v) -{ - unsigned long flags; - int temp; - - raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ - temp = v->counter; - temp += i; - v->counter = temp; - raw_local_irq_restore(flags); - - return temp; -} -#endif - -/** - * atomic_sub_return - subtract integer from atomic variable - * @i: integer value to subtract - * @v: pointer of type atomic_t - * - * Atomically subtracts @i from @v and returns the result - */ -#ifndef atomic_sub_return -static inline int atomic_sub_return(int i, atomic_t *v) -{ - unsigned long flags; - int temp; - - raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ - temp = v->counter; - temp -= i; - v->counter = temp; - raw_local_irq_restore(flags); - - return temp; -} -#endif - static inline int atomic_add_negative(int i, atomic_t *v) { return atomic_add_return(i, v) < 0; @@ -139,49 +177,11 @@ static inline void atomic_dec(atomic_t *v) 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; -} - -/** - * atomic_clear_mask - Atomically clear bits in atomic variable - * @mask: Mask of the bits to be cleared - * @v: pointer of type atomic_t - * - * Atomically clears the bits set in @mask from @v - */ -#ifndef atomic_clear_mask -static inline void atomic_clear_mask(unsigned long mask, atomic_t *v) -{ - unsigned long flags; - - mask = ~mask; - raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ - v->counter &= mask; - raw_local_irq_restore(flags); + int c, old; + c = atomic_read(v); + while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) + c = old; + return c; } -#endif - -/** - * atomic_set_mask - Atomically set bits in atomic variable - * @mask: Mask of the bits to be set - * @v: pointer of type atomic_t - * - * Atomically sets the bits set in @mask in @v - */ -#ifndef atomic_set_mask -static inline void atomic_set_mask(unsigned int mask, atomic_t *v) -{ - unsigned long flags; - - raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ - v->counter |= mask; - raw_local_irq_restore(flags); -} -#endif -#endif /* __KERNEL__ */ #endif /* __ASM_GENERIC_ATOMIC_H */ diff --git a/include/asm-generic/atomic64.h b/include/asm-generic/atomic64.h index b18ce4f9ee3d..30ad9c86cebb 100644 --- a/include/asm-generic/atomic64.h +++ b/include/asm-generic/atomic64.h @@ -20,10 +20,22 @@ typedef struct { extern long long atomic64_read(const atomic64_t *v); extern void atomic64_set(atomic64_t *v, long long i); -extern void atomic64_add(long long a, atomic64_t *v); -extern long long atomic64_add_return(long long a, atomic64_t *v); -extern void atomic64_sub(long long a, atomic64_t *v); -extern long long atomic64_sub_return(long long a, atomic64_t *v); + +#define ATOMIC64_OP(op) \ +extern void atomic64_##op(long long a, atomic64_t *v); + +#define ATOMIC64_OP_RETURN(op) \ +extern long long atomic64_##op##_return(long long a, atomic64_t *v); + +#define ATOMIC64_OPS(op) ATOMIC64_OP(op) ATOMIC64_OP_RETURN(op) + +ATOMIC64_OPS(add) +ATOMIC64_OPS(sub) + +#undef ATOMIC64_OPS +#undef ATOMIC64_OP_RETURN +#undef ATOMIC64_OP + extern long long atomic64_dec_if_positive(atomic64_t *v); extern long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n); extern long long atomic64_xchg(atomic64_t *v, long long new); -- cgit v1.2.3 From 2291059c852706c6f5ffb400366042b7625066cd Mon Sep 17 00:00:00 2001 From: Pranith Kumar Date: Tue, 23 Sep 2014 10:29:50 -0400 Subject: locking,arch: Use ACCESS_ONCE() instead of cast to volatile in atomic_read() Use the much more reader friendly ACCESS_ONCE() instead of the cast to volatile. This is purely a stylistic change. Signed-off-by: Pranith Kumar Acked-by: Jesper Nilsson Acked-by: Hans-Christian Egtvedt Acked-by: Max Filippov Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/1411482607-20948-1-git-send-email-bobby.prani@gmail.com Signed-off-by: Ingo Molnar --- arch/alpha/include/asm/atomic.h | 4 ++-- arch/arm/include/asm/atomic.h | 2 +- arch/arm64/include/asm/atomic.h | 4 ++-- arch/avr32/include/asm/atomic.h | 2 +- arch/cris/include/asm/atomic.h | 2 +- arch/frv/include/asm/atomic.h | 2 +- arch/ia64/include/asm/atomic.h | 4 ++-- arch/m32r/include/asm/atomic.h | 2 +- arch/m68k/include/asm/atomic.h | 2 +- arch/mips/include/asm/atomic.h | 4 ++-- arch/parisc/include/asm/atomic.h | 4 ++-- arch/sh/include/asm/atomic.h | 2 +- arch/sparc/include/asm/atomic_32.h | 2 +- arch/sparc/include/asm/atomic_64.h | 4 ++-- arch/x86/include/asm/atomic.h | 2 +- arch/x86/include/asm/atomic64_64.h | 2 +- arch/xtensa/include/asm/atomic.h | 2 +- include/asm-generic/atomic.h | 2 +- 18 files changed, 24 insertions(+), 24 deletions(-) (limited to 'include') diff --git a/arch/alpha/include/asm/atomic.h b/arch/alpha/include/asm/atomic.h index 6fbb53a13049..8f8eafbedd7c 100644 --- a/arch/alpha/include/asm/atomic.h +++ b/arch/alpha/include/asm/atomic.h @@ -17,8 +17,8 @@ #define ATOMIC_INIT(i) { (i) } #define ATOMIC64_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) -#define atomic64_read(v) (*(volatile long *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) +#define atomic64_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v,i) ((v)->counter = (i)) #define atomic64_set(v,i) ((v)->counter = (i)) diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h index 832f1cdfcd6a..e22c11970b7b 100644 --- a/arch/arm/include/asm/atomic.h +++ b/arch/arm/include/asm/atomic.h @@ -27,7 +27,7 @@ * strex/ldrex monitor on some implementations. The reason we can use it for * atomic_set() is the clrex or dummy strex done on every exception return. */ -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v,i) (((v)->counter) = (i)) #if __LINUX_ARM_ARCH__ >= 6 diff --git a/arch/arm64/include/asm/atomic.h b/arch/arm64/include/asm/atomic.h index b83c325e587f..7047051ded40 100644 --- a/arch/arm64/include/asm/atomic.h +++ b/arch/arm64/include/asm/atomic.h @@ -35,7 +35,7 @@ * strex/ldrex monitor on some implementations. The reason we can use it for * atomic_set() is the clrex or dummy strex done on every exception return. */ -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v,i) (((v)->counter) = (i)) /* @@ -139,7 +139,7 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u) */ #define ATOMIC64_INIT(i) { (i) } -#define atomic64_read(v) (*(volatile long *)&(v)->counter) +#define atomic64_read(v) ACCESS_ONCE((v)->counter) #define atomic64_set(v,i) (((v)->counter) = (i)) #define ATOMIC64_OP(op, asm_op) \ diff --git a/arch/avr32/include/asm/atomic.h b/arch/avr32/include/asm/atomic.h index 83e980a4e483..2d07ce1c5327 100644 --- a/arch/avr32/include/asm/atomic.h +++ b/arch/avr32/include/asm/atomic.h @@ -19,7 +19,7 @@ #define ATOMIC_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v, i) (((v)->counter) = i) #define ATOMIC_OP_RETURN(op, asm_op, asm_con) \ diff --git a/arch/cris/include/asm/atomic.h b/arch/cris/include/asm/atomic.h index 0033f9dfea24..279766a70664 100644 --- a/arch/cris/include/asm/atomic.h +++ b/arch/cris/include/asm/atomic.h @@ -17,7 +17,7 @@ #define ATOMIC_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v,i) (((v)->counter) = (i)) /* These should be written in asm but we do it in C for now. */ diff --git a/arch/frv/include/asm/atomic.h b/arch/frv/include/asm/atomic.h index f6c3a1690101..102190a61d65 100644 --- a/arch/frv/include/asm/atomic.h +++ b/arch/frv/include/asm/atomic.h @@ -31,7 +31,7 @@ */ #define ATOMIC_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v, i) (((v)->counter) = (i)) #ifndef CONFIG_FRV_OUTOFLINE_ATOMIC_OPS diff --git a/arch/ia64/include/asm/atomic.h b/arch/ia64/include/asm/atomic.h index 42919a831c6c..0bf03501fe5c 100644 --- a/arch/ia64/include/asm/atomic.h +++ b/arch/ia64/include/asm/atomic.h @@ -21,8 +21,8 @@ #define ATOMIC_INIT(i) { (i) } #define ATOMIC64_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) -#define atomic64_read(v) (*(volatile long *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) +#define atomic64_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v,i) (((v)->counter) = (i)) #define atomic64_set(v,i) (((v)->counter) = (i)) diff --git a/arch/m32r/include/asm/atomic.h b/arch/m32r/include/asm/atomic.h index 3946b2c8d971..31bb74adba08 100644 --- a/arch/m32r/include/asm/atomic.h +++ b/arch/m32r/include/asm/atomic.h @@ -28,7 +28,7 @@ * * Atomically reads the value of @v. */ -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) /** * atomic_set - set atomic variable diff --git a/arch/m68k/include/asm/atomic.h b/arch/m68k/include/asm/atomic.h index 663d4ba2462c..e85f047fb072 100644 --- a/arch/m68k/include/asm/atomic.h +++ b/arch/m68k/include/asm/atomic.h @@ -17,7 +17,7 @@ #define ATOMIC_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v, i) (((v)->counter) = i) /* diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h index f3ee721fe61d..6dd6bfc607e9 100644 --- a/arch/mips/include/asm/atomic.h +++ b/arch/mips/include/asm/atomic.h @@ -29,7 +29,7 @@ * * Atomically reads the value of @v. */ -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) /* * atomic_set - set atomic variable @@ -306,7 +306,7 @@ static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u) * @v: pointer of type atomic64_t * */ -#define atomic64_read(v) (*(volatile long *)&(v)->counter) +#define atomic64_read(v) ACCESS_ONCE((v)->counter) /* * atomic64_set - set atomic variable diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h index 219750bb4ae7..226f8ca993f6 100644 --- a/arch/parisc/include/asm/atomic.h +++ b/arch/parisc/include/asm/atomic.h @@ -67,7 +67,7 @@ static __inline__ void atomic_set(atomic_t *v, int i) static __inline__ int atomic_read(const atomic_t *v) { - return (*(volatile int *)&(v)->counter); + return ACCESS_ONCE((v)->counter); } /* exported interface */ @@ -204,7 +204,7 @@ atomic64_set(atomic64_t *v, s64 i) static __inline__ s64 atomic64_read(const atomic64_t *v) { - return (*(volatile long *)&(v)->counter); + return ACCESS_ONCE((v)->counter); } #define atomic64_inc(v) (atomic64_add( 1,(v))) diff --git a/arch/sh/include/asm/atomic.h b/arch/sh/include/asm/atomic.h index f57b8a6743b3..05b9f74ce2d5 100644 --- a/arch/sh/include/asm/atomic.h +++ b/arch/sh/include/asm/atomic.h @@ -14,7 +14,7 @@ #define ATOMIC_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v,i) ((v)->counter = (i)) #if defined(CONFIG_GUSA_RB) diff --git a/arch/sparc/include/asm/atomic_32.h b/arch/sparc/include/asm/atomic_32.h index 7b024f02a7ce..765c1776ec9f 100644 --- a/arch/sparc/include/asm/atomic_32.h +++ b/arch/sparc/include/asm/atomic_32.h @@ -26,7 +26,7 @@ int atomic_cmpxchg(atomic_t *, int, int); int __atomic_add_unless(atomic_t *, int, int); void atomic_set(atomic_t *, int); -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #define atomic_add(i, v) ((void)atomic_add_return( (int)(i), (v))) #define atomic_sub(i, v) ((void)atomic_add_return(-(int)(i), (v))) diff --git a/arch/sparc/include/asm/atomic_64.h b/arch/sparc/include/asm/atomic_64.h index 7e4ca1e73cd9..4082749913ce 100644 --- a/arch/sparc/include/asm/atomic_64.h +++ b/arch/sparc/include/asm/atomic_64.h @@ -14,8 +14,8 @@ #define ATOMIC_INIT(i) { (i) } #define ATOMIC64_INIT(i) { (i) } -#define atomic_read(v) (*(volatile int *)&(v)->counter) -#define atomic64_read(v) (*(volatile long *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) +#define atomic64_read(v) ACCESS_ONCE((v)->counter) #define atomic_set(v, i) (((v)->counter) = i) #define atomic64_set(v, i) (((v)->counter) = i) diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h index bf20c817ed34..5e5cd123fdfb 100644 --- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h @@ -24,7 +24,7 @@ */ static inline int atomic_read(const atomic_t *v) { - return (*(volatile int *)&(v)->counter); + return ACCESS_ONCE((v)->counter); } /** diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h index 46e9052bbd28..f8d273e18516 100644 --- a/arch/x86/include/asm/atomic64_64.h +++ b/arch/x86/include/asm/atomic64_64.h @@ -18,7 +18,7 @@ */ static inline long atomic64_read(const atomic64_t *v) { - return (*(volatile long *)&(v)->counter); + return ACCESS_ONCE((v)->counter); } /** diff --git a/arch/xtensa/include/asm/atomic.h b/arch/xtensa/include/asm/atomic.h index 626676660b80..00b7d46b35b8 100644 --- a/arch/xtensa/include/asm/atomic.h +++ b/arch/xtensa/include/asm/atomic.h @@ -47,7 +47,7 @@ * * Atomically reads the value of @v. */ -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) /** * atomic_set - set atomic variable diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h index 56d4d36e1531..1973ad2b13f4 100644 --- a/include/asm-generic/atomic.h +++ b/include/asm-generic/atomic.h @@ -126,7 +126,7 @@ ATOMIC_OP(or, |) * Atomically reads the value of @v. */ #ifndef atomic_read -#define atomic_read(v) (*(volatile int *)&(v)->counter) +#define atomic_read(v) ACCESS_ONCE((v)->counter) #endif /** -- cgit v1.2.3