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| author | Elena Reshetova <elena.reshetova@intel.com> | 2019-01-30 12:18:51 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-02-04 09:03:31 +0100 |
| commit | 47b8f3ab9c49daa824af848f9e02889662d8638f (patch) | |
| tree | bd42ab897748eafaacdc5d0bb97256a678cee3d5 /arch | |
| parent | locking/qspinlock_stat: Track the no MCS node available case (diff) | |
| download | linux-47b8f3ab9c49daa824af848f9e02889662d8638f.tar.xz linux-47b8f3ab9c49daa824af848f9e02889662d8638f.zip | |
refcount_t: Add ACQUIRE ordering on success for dec(sub)_and_test() variants
This adds an smp_acquire__after_ctrl_dep() barrier on successful
decrease of refcounter value from 1 to 0 for refcount_dec(sub)_and_test
variants and therefore gives stronger memory ordering guarantees than
prior versions of these functions.
Co-developed-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: dvyukov@google.com
Cc: keescook@chromium.org
Cc: stern@rowland.harvard.edu
Link: https://lkml.kernel.org/r/1548847131-27854-2-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/refcount.h | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/arch/x86/include/asm/refcount.h b/arch/x86/include/asm/refcount.h index dbaed55c1c24..232f856e0db0 100644 --- a/arch/x86/include/asm/refcount.h +++ b/arch/x86/include/asm/refcount.h @@ -67,16 +67,30 @@ static __always_inline void refcount_dec(refcount_t *r) static __always_inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) { - return GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl", + bool ret = GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl", REFCOUNT_CHECK_LT_ZERO, r->refs.counter, e, "er", i, "cx"); + + if (ret) { + smp_acquire__after_ctrl_dep(); + return true; + } + + return false; } static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r) { - return GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl", - REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, e, "cx"); + bool ret = GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl", + REFCOUNT_CHECK_LT_ZERO, + r->refs.counter, e, "cx"); + + if (ret) { + smp_acquire__after_ctrl_dep(); + return true; + } + + return false; } static __always_inline __must_check |