[PATCH 4/9] locking/qrwlock: implement queue_write_unlock using smp_store_release
From: Will Deacon <hidden>
Date: 2015-07-07 17:24:20
Also in:
linux-arch
Subsystem:
generic include/asm header files, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Arnd Bergmann, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
smp_store_release supports byte accesses, so use that in writer unlock and remove the conditional macro override. Signed-off-by: Will Deacon <redacted> --- arch/x86/include/asm/qrwlock.h | 10 ---------- include/asm-generic/qrwlock.h | 9 +-------- 2 files changed, 1 insertion(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/qrwlock.h b/arch/x86/include/asm/qrwlock.h
index a8810bf135ab..c537cbb038a7 100644
--- a/arch/x86/include/asm/qrwlock.h
+++ b/arch/x86/include/asm/qrwlock.h@@ -2,16 +2,6 @@ #define _ASM_X86_QRWLOCK_H #include <asm-generic/qrwlock_types.h> - -#ifndef CONFIG_X86_PPRO_FENCE -#define queued_write_unlock queued_write_unlock -static inline void queued_write_unlock(struct qrwlock *lock) -{ - barrier(); - ACCESS_ONCE(*(u8 *)&lock->cnts) = 0; -} -#endif - #include <asm-generic/qrwlock.h> #endif /* _ASM_X86_QRWLOCK_H */
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
index deb9e8b0eb9e..eb673dde8879 100644
--- a/include/asm-generic/qrwlock.h
+++ b/include/asm-generic/qrwlock.h@@ -134,21 +134,14 @@ static inline void queued_read_unlock(struct qrwlock *lock) atomic_sub(_QR_BIAS, &lock->cnts); } -#ifndef queued_write_unlock /** * queued_write_unlock - release write lock of a queue rwlock * @lock : Pointer to queue rwlock structure */ static inline void queued_write_unlock(struct qrwlock *lock) { - /* - * If the writer field is atomic, it can be cleared directly. - * Otherwise, an atomic subtraction will be used to clear it. - */ - smp_mb__before_atomic(); - atomic_sub(_QW_LOCKED, &lock->cnts); + smp_store_release((u8 *)&lock->cnts, 0); } -#endif /* * Remapping rwlock architecture specific functions to the corresponding
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2.1.4