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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
csky: Fixup asm/cmpxchg.h with correct ordering barrier
Optimize the performance of cmpxchg by using more fine-grained
acquire/release barriers.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
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arch/csky/include/asm/cmpxchg.h
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arch/csky/include/asm/cmpxchg.h
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#ifndef __ASM_CSKY_CMPXCHG_H
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#define __ASM_CSKY_CMPXCHG_H
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#ifdef CONFIG_CPU_HAS_LDSTEX
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#ifdef CONFIG_SMP
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#include <asm/barrier.h>
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extern void __bad_xchg(void);
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#define __xchg(new, ptr, size) \
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#define __xchg_relaxed(new, ptr, size) \
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({ \
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__typeof__(ptr) __ptr = (ptr); \
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__typeof__(new) __new = (new); \
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unsigned long tmp; \
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switch (size) { \
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case 4: \
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smp_mb(); \
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asm volatile ( \
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"1: ldex.w %0, (%3) \n" \
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" mov %1, %2 \n" \
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: "=&r" (__ret), "=&r" (tmp) \
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: "r" (__new), "r"(__ptr) \
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:); \
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smp_mb(); \
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break; \
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default: \
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__bad_xchg(); \
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__ret; \
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})
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#define xchg(ptr, x) (__xchg((x), (ptr), sizeof(*(ptr))))
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#define xchg_relaxed(ptr, x) \
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(__xchg_relaxed((x), (ptr), sizeof(*(ptr))))
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#define __cmpxchg(ptr, old, new, size) \
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#define __cmpxchg_relaxed(ptr, old, new, size) \
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({ \
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__typeof__(ptr) __ptr = (ptr); \
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__typeof__(new) __new = (new); \
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__typeof__(*(ptr)) __ret; \
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switch (size) { \
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case 4: \
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smp_mb(); \
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asm volatile ( \
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"1: ldex.w %0, (%3) \n" \
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" cmpne %0, %4 \n" \
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: "=&r" (__ret), "=&r" (__tmp) \
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: "r" (__new), "r"(__ptr), "r"(__old) \
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:); \
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smp_mb(); \
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break; \
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default: \
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__bad_xchg(); \
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__ret; \
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})
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#define cmpxchg(ptr, o, n) \
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(__cmpxchg((ptr), (o), (n), sizeof(*(ptr))))
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#define cmpxchg_relaxed(ptr, o, n) \
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(__cmpxchg_relaxed((ptr), (o), (n), sizeof(*(ptr))))
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#define cmpxchg(ptr, o, n) \
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({ \
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__typeof__(*(ptr)) __ret; \
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__smp_release_fence(); \
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__ret = cmpxchg_relaxed(ptr, o, n); \
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__smp_acquire_fence(); \
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__ret; \
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})
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#else
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#include <asm-generic/cmpxchg.h>
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#endif