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The following two commits:79d442461d("locking/xchg/alpha: Clean up barrier usage by using smp_mb() in place of __ASM__MB")472e8c55cf("locking/xchg/alpha: Fix xchg() and cmpxchg() memory ordering bugs") ... ended up adding unnecessary barriers to the _local() variants on Alpha, which the previous code took care to avoid. Fix them by adding the smp_mb() into the cmpxchg() macro rather than into the ____cmpxchg() variants. Reported-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrea Parri <parri.andrea@gmail.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-alpha@vger.kernel.org Fixes:472e8c55cf("locking/xchg/alpha: Fix xchg() and cmpxchg() memory ordering bugs") Fixes:79d442461d("locking/xchg/alpha: Clean up barrier usage by using smp_mb() in place of __ASM__MB") Link: http://lkml.kernel.org/r/1519704058-13430-1-git-send-email-parri.andrea@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ALPHA_CMPXCHG_H
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#define _ALPHA_CMPXCHG_H
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/*
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* Atomic exchange routines.
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*/
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#define ____xchg(type, args...) __xchg ## type ## _local(args)
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#define ____cmpxchg(type, args...) __cmpxchg ## type ## _local(args)
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#include <asm/xchg.h>
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#define xchg_local(ptr, x) \
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({ \
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__typeof__(*(ptr)) _x_ = (x); \
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(__typeof__(*(ptr))) __xchg_local((ptr), (unsigned long)_x_, \
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sizeof(*(ptr))); \
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})
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#define cmpxchg_local(ptr, o, n) \
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({ \
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__typeof__(*(ptr)) _o_ = (o); \
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__typeof__(*(ptr)) _n_ = (n); \
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(__typeof__(*(ptr))) __cmpxchg_local((ptr), (unsigned long)_o_, \
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(unsigned long)_n_, \
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sizeof(*(ptr))); \
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})
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#define cmpxchg64_local(ptr, o, n) \
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({ \
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BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
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cmpxchg_local((ptr), (o), (n)); \
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})
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#undef ____xchg
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#undef ____cmpxchg
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#define ____xchg(type, args...) __xchg ##type(args)
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#define ____cmpxchg(type, args...) __cmpxchg ##type(args)
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#include <asm/xchg.h>
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/*
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* The leading and the trailing memory barriers guarantee that these
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* operations are fully ordered.
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*/
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#define xchg(ptr, x) \
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({ \
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__typeof__(*(ptr)) __ret; \
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__typeof__(*(ptr)) _x_ = (x); \
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smp_mb(); \
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__ret = (__typeof__(*(ptr))) \
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__xchg((ptr), (unsigned long)_x_, sizeof(*(ptr))); \
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smp_mb(); \
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__ret; \
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})
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#define cmpxchg(ptr, o, n) \
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({ \
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__typeof__(*(ptr)) __ret; \
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__typeof__(*(ptr)) _o_ = (o); \
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__typeof__(*(ptr)) _n_ = (n); \
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smp_mb(); \
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__ret = (__typeof__(*(ptr))) __cmpxchg((ptr), \
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(unsigned long)_o_, (unsigned long)_n_, sizeof(*(ptr)));\
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smp_mb(); \
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__ret; \
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})
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#define cmpxchg64(ptr, o, n) \
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({ \
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BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
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cmpxchg((ptr), (o), (n)); \
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})
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#undef ____cmpxchg
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#endif /* _ALPHA_CMPXCHG_H */
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