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Date: Thu, 30 Aug 2018 16:43:44 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Will Deacon <will.deacon@....com> Cc: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>, "mingo@...nel.org" <mingo@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Alexey.Brodkin@...opsys.com" <Alexey.Brodkin@...opsys.com>, "Vineet.Gupta1@...opsys.com" <Vineet.Gupta1@...opsys.com>, "tglx@...utronix.de" <tglx@...utronix.de>, "linux-snps-arc@...ts.infradead.org" <linux-snps-arc@...ts.infradead.org>, "yamada.masahiro@...ionext.com" <yamada.masahiro@...ionext.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org> Subject: Re: Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash On Thu, Aug 30, 2018 at 04:29:20PM +0200, Peter Zijlstra wrote: > Also, once it all works, they should look at switching to _relaxed > atomics for LL/SC. A little something like so.. should save a few smp_mb(). --- diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h index 4e0072730241..714b54c308b0 100644 --- a/arch/arc/include/asm/atomic.h +++ b/arch/arc/include/asm/atomic.h @@ -44,7 +44,7 @@ static inline void atomic_##op(int i, atomic_t *v) \ } \ #define ATOMIC_OP_RETURN(op, c_op, asm_op) \ -static inline int atomic_##op##_return(int i, atomic_t *v) \ +static inline int atomic_##op##_return_relaxed(int i, atomic_t *v) \ { \ unsigned int val; \ \ @@ -69,8 +69,11 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \ return val; \ } +#define atomic_add_return_relaxed atomic_add_return_relaxed +#define atomic_sub_return_relaxed atomic_sub_return_relaxed + #define ATOMIC_FETCH_OP(op, c_op, asm_op) \ -static inline int atomic_fetch_##op(int i, atomic_t *v) \ +static inline int atomic_fetch_##op##_relaxed(int i, atomic_t *v) \ { \ unsigned int val, orig; \ \ @@ -96,6 +99,14 @@ static inline int atomic_fetch_##op(int i, atomic_t *v) \ return orig; \ } +#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed +#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed + +#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed +#define atomic_fetch_andnot_relaxed atomic_fetch_andnot_relaxed +#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed +#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed + #else /* !CONFIG_ARC_HAS_LLSC */ #ifndef CONFIG_SMP @@ -379,7 +390,7 @@ static inline void atomic64_##op(long long a, atomic64_t *v) \ } \ #define ATOMIC64_OP_RETURN(op, op1, op2) \ -static inline long long atomic64_##op##_return(long long a, atomic64_t *v) \ +static inline long long atomic64_##op##_return_relaxed(long long a, atomic64_t *v) \ { \ unsigned long long val; \ \ @@ -401,8 +412,11 @@ static inline long long atomic64_##op##_return(long long a, atomic64_t *v) \ return val; \ } +#define atomic64_add_return_relaxed atomic64_add_return_relaxed +#define atomic64_sub_return_relaxed atomic64_sub_return_relaxed + #define ATOMIC64_FETCH_OP(op, op1, op2) \ -static inline long long atomic64_fetch_##op(long long a, atomic64_t *v) \ +static inline long long atomic64_fetch_##op##_relaxed(long long a, atomic64_t *v) \ { \ unsigned long long val, orig; \ \ @@ -424,6 +438,14 @@ static inline long long atomic64_fetch_##op(long long a, atomic64_t *v) \ return orig; \ } +#define atomic64_fetch_add_relaxed atomic64_fetch_add_relaxed +#define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed + +#define atomic64_fetch_and_relaxed atomic64_fetch_and_relaxed +#define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot_relaxed +#define atomic64_fetch_or_relaxed atomic64_fetch_or_relaxed +#define atomic64_fetch_xor_relaxed atomic64_fetch_xor_relaxed + #define ATOMIC64_OPS(op, op1, op2) \ ATOMIC64_OP(op, op1, op2) \ ATOMIC64_OP_RETURN(op, op1, op2) \ @@ -434,6 +456,12 @@ static inline long long atomic64_fetch_##op(long long a, atomic64_t *v) \ ATOMIC64_OPS(add, add.f, adc) ATOMIC64_OPS(sub, sub.f, sbc) + +#undef ATOMIC64_OPS +#define ATOMIC64_OPS(op, op1, op2) \ + ATOMIC64_OP(op, op1, op2) \ + ATOMIC64_FETCH_OP(op, op1, op2) + ATOMIC64_OPS(and, and, and) ATOMIC64_OPS(andnot, bic, bic) ATOMIC64_OPS(or, or, or)
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