Greg Kroah-Hartman wrote:
On Mon, Aug 05, 2019 at 11:11:01PM +0300, Jari Ruusu wrote:
Peter Zijlstra's "x86/atomic: Fix smp_mb__{before,after}_atomic()" upstream commit 69d927bba39517d0980462efc051875b7f4db185 seems to be missing/lost from 4.9 and older stable kernels.
Can you send properly backported and tested patches?
linux-4.4 backport of "x86/atomic: Fix smp_mb__{before,after}_atomic()". Tested.
Signed-off-by: Jari Ruusu jari.ruusu@gmail.com
--- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h @@ -49,7 +49,7 @@ { asm volatile(LOCK_PREFIX "addl %1,%0" : "+m" (v->counter) - : "ir" (i)); + : "ir" (i) : "memory"); }
/** @@ -63,7 +63,7 @@ { asm volatile(LOCK_PREFIX "subl %1,%0" : "+m" (v->counter) - : "ir" (i)); + : "ir" (i) : "memory"); }
/** @@ -89,7 +89,7 @@ static __always_inline void atomic_inc(atomic_t *v) { asm volatile(LOCK_PREFIX "incl %0" - : "+m" (v->counter)); + : "+m" (v->counter) :: "memory"); }
/** @@ -101,7 +101,7 @@ static __always_inline void atomic_dec(atomic_t *v) { asm volatile(LOCK_PREFIX "decl %0" - : "+m" (v->counter)); + : "+m" (v->counter) :: "memory"); }
/** --- a/arch/x86/include/asm/atomic64_64.h +++ b/arch/x86/include/asm/atomic64_64.h @@ -44,7 +44,7 @@ { asm volatile(LOCK_PREFIX "addq %1,%0" : "=m" (v->counter) - : "er" (i), "m" (v->counter)); + : "er" (i), "m" (v->counter) : "memory"); }
/** @@ -58,7 +58,7 @@ { asm volatile(LOCK_PREFIX "subq %1,%0" : "=m" (v->counter) - : "er" (i), "m" (v->counter)); + : "er" (i), "m" (v->counter) : "memory"); }
/** @@ -85,7 +85,7 @@ { asm volatile(LOCK_PREFIX "incq %0" : "=m" (v->counter) - : "m" (v->counter)); + : "m" (v->counter) : "memory"); }
/** @@ -98,7 +98,7 @@ { asm volatile(LOCK_PREFIX "decq %0" : "=m" (v->counter) - : "m" (v->counter)); + : "m" (v->counter) : "memory"); }
/** --- a/arch/x86/include/asm/barrier.h +++ b/arch/x86/include/asm/barrier.h @@ -116,7 +116,7 @@ #endif
/* Atomic operations are already serializing on x86 */ -#define smp_mb__before_atomic() barrier() -#define smp_mb__after_atomic() barrier() +#define smp_mb__before_atomic() do { } while (0) +#define smp_mb__after_atomic() do { } while (0)
#endif /* _ASM_X86_BARRIER_H */