search for: __smp_mb

...body does include asm-generic/barrier.h, you could > simply #undef the __smp version at the end of that, once we've generated > all the regular primitives from it, no? Not so simple - that's why I mentioned using inline functions. The new smp_* _macros_ are: +#define smp_mb() __smp_mb() which means if we simply #undef __smp_mb(), smp_mb() then points at something which is no longer available, and we'll end up with errors saying that __smp_mb() doesn't exist. My suggestion was to change: #ifndef smp_mb #define smp_mb() __smp_mb() #endif to: #ifndef smp_mb static inli...

...body does include asm-generic/barrier.h, you could > simply #undef the __smp version at the end of that, once we've generated > all the regular primitives from it, no? Not so simple - that's why I mentioned using inline functions. The new smp_* _macros_ are: +#define smp_mb() __smp_mb() which means if we simply #undef __smp_mb(), smp_mb() then points at something which is no longer available, and we'll end up with errors saying that __smp_mb() doesn't exist. My suggestion was to change: #ifndef smp_mb #define smp_mb() __smp_mb() #endif to: #ifndef smp_mb static inli...

...lly is an artifact of interfacing with an SMP host while running an UP kernel, but since we have (at least) two users, it seems to make sense to put these APIs in a central place. In fact, smp_ barriers are stubs on !SMP, so they can be defined as follows: arch/XXX/include/asm/barrier.h: #define __smp_mb() DOSOMETHING include/asm-generic/barrier.h: #ifdef CONFIG_SMP #define smp_mb() __smp_mb() #else #define smp_mb() barrier() #endif This has the benefit of cleaning out a bunch of duplicated ifdefs on a bunch of architectures - this patchset brings about a net reduction in LOC, compensated for by...

...lly is an artifact of interfacing with an SMP host while running an UP kernel, but since we have (at least) two users, it seems to make sense to put these APIs in a central place. In fact, smp_ barriers are stubs on !SMP, so they can be defined as follows: arch/XXX/include/asm/barrier.h: #define __smp_mb() DOSOMETHING include/asm-generic/barrier.h: #ifdef CONFIG_SMP #define smp_mb() __smp_mb() #else #define smp_mb() barrier() #endif This has the benefit of cleaning out a bunch of duplicated ifdefs on a bunch of architectures - this patchset brings about a net reduction in LOC, compensated for by...

...clude/asm/barrier.h > @@ -26,18 +26,21 @@ > #define wmb() barrier() > #define dma_rmb() mb() > #define dma_wmb() mb() > -#define smp_mb() mb() > -#define smp_rmb() rmb() > -#define smp_wmb() wmb() > - > -#define smp_store_release(p, v) \ > +#define __smp_mb() mb() > +#define __smp_rmb() rmb() > +#define __smp_wmb() wmb() > +#define smp_mb() __smp_mb() > +#define smp_rmb() __smp_rmb() > +#define smp_wmb() __smp_wmb() Why define the smp_*mb() primitives here? Would not the inclusion of asm-generic/barrier.h do this?

...clude/asm/barrier.h > @@ -26,18 +26,21 @@ > #define wmb() barrier() > #define dma_rmb() mb() > #define dma_wmb() mb() > -#define smp_mb() mb() > -#define smp_rmb() rmb() > -#define smp_wmb() wmb() > - > -#define smp_store_release(p, v) \ > +#define __smp_mb() mb() > +#define __smp_rmb() rmb() > +#define __smp_wmb() wmb() > +#define smp_mb() __smp_mb() > +#define smp_rmb() __smp_rmb() > +#define smp_wmb() __smp_wmb() Why define the smp_*mb() primitives here? Would not the inclusion of asm-generic/barrier.h do this?

...() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "sfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #else #define mb() asm volatile("mfence":::"memory") @@ -30,7 +30,11 @@ #endif #define dma_wmb() barrier() -#define __smp_mb() mb() +#ifdef CONFIG_X86_32 +#define __smp_mb() asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc") +#else +#define __smp_mb() asm volatile("lock; addl $0,-4(%%rsp)" ::: "memory", "cc") +#endif #define __smp_rmb() dma_rmb() #defi...

...() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "sfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #else #define mb() asm volatile("mfence":::"memory") @@ -30,7 +30,11 @@ #endif #define dma_wmb() barrier() -#define __smp_mb() mb() +#ifdef CONFIG_X86_32 +#define __smp_mb() asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc") +#else +#define __smp_mb() asm volatile("lock; addl $0,-4(%%rsp)" ::: "memory", "cc") +#endif #define __smp_rmb() dma_rmb() #defi...

...p_load_acquire(p) \ | ({ \ | __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \ | compiletime_assert_atomic_type(*p); \ | __smp_mb(); \ | (typeof(*p))___p1; \ | }) | #endif ... where the __smp_mb() would be alpha's mb() from earlier in the patch context, i.e. | #define mb() __asm__ __volatile__("mb": : :&quo...

...p_load_acquire(p) \ | ({ \ | __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \ | compiletime_assert_atomic_type(*p); \ | __smp_mb(); \ | (typeof(*p))___p1; \ | }) | #endif ... where the __smp_mb() would be alpha's mb() from earlier in the patch context, i.e. | #define mb() __asm__ __volatile__("mb": : :&quo...

...(_r)->req_prod_pvt; \ - wmb(); /* back sees requests /before/ updated producer index */ \ + __smp_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = __new; \ - mb(); /* back sees new requests /before/ we check req_event */ \ + __smp_mb(); /* back sees new requests /before/ we check req_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -260,9 +260,9 @@ struct __name##_back_ring { \ #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify...

On Wed, Jan 27, 2016 at 7:10 AM, Michael S. Tsirkin <mst at redhat.com> wrote: > > -#define __smp_mb() mb() > +#define __smp_mb() asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc") So this doesn't look right for x86-64. Using %esp rather than %rsp. How did that even work for you? Linus

On Wed, Jan 27, 2016 at 7:10 AM, Michael S. Tsirkin <mst at redhat.com> wrote: > > -#define __smp_mb() mb() > +#define __smp_mb() asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc") So this doesn't look right for x86-64. Using %esp rather than %rsp. How did that even work for you? Linus

On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote: > On Sat, Jan 02, 2016 at 11:24:38AM +0000, Russell King - ARM Linux wrote: > > My only concern is that it gives people an additional handle onto a > > "new" set of barriers - just because they're prefixed with __* > > unfortunately doesn't stop anyone from using it (been there with >

On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote: > On Sat, Jan 02, 2016 at 11:24:38AM +0000, Russell King - ARM Linux wrote: > > My only concern is that it gives people an additional handle onto a > > "new" set of barriers - just because they're prefixed with __* > > unfortunately doesn't stop anyone from using it (been there with >

...lly is an artifact of interfacing with an SMP host while running an UP kernel, but since we have (at least) two users, it seems to make sense to put these APIs in a central place. In fact, smp_ barriers are stubs on !SMP, so they can be defined as follows: arch/XXX/include/asm/barrier.h: #define __smp_mb() DOSOMETHING include/asm-generic/barrier.h: #ifdef CONFIG_SMP #define smp_mb() __smp_mb() #else #define smp_mb() barrier() #endif This has the benefit of cleaning out a bunch of duplicated ifdefs on a bunch of architectures - this patchset brings about a net reduction in LOC, even with new barr...

...lly is an artifact of interfacing with an SMP host while running an UP kernel, but since we have (at least) two users, it seems to make sense to put these APIs in a central place. In fact, smp_ barriers are stubs on !SMP, so they can be defined as follows: arch/XXX/include/asm/barrier.h: #define __smp_mb() DOSOMETHING include/asm-generic/barrier.h: #ifdef CONFIG_SMP #define smp_mb() __smp_mb() #else #define smp_mb() barrier() #endif This has the benefit of cleaning out a bunch of duplicated ifdefs on a bunch of architectures - this patchset brings about a net reduction in LOC, even with new barr...

...() -#define smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0) -#else /* !SMP */ -#define smp_mb() barrier() -#define smp_rmb() barrier() -#define smp_wmb() barrier() -#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0) -#endif /* SMP */ +#define __smp_mb() mb() +#define __smp_rmb() dma_rmb() +#define __smp_wmb() barrier() +#define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0) #if defined(CONFIG_X86_PPRO_FENCE) @@ -50,31 +43,31 @@ * model and we should fall back to full barriers. */ -#define smp_store_release(p,...

...lly is an artifact of interfacing with an SMP host while running an UP kernel, but since we have (at least) two users, it seems to make sense to put these APIs in a central place. In fact, smp_ barriers are stubs on !SMP, so they can be defined as follows: arch/XXX/include/asm/barrier.h: #define __smp_mb() DOSOMETHING include/asm-generic/barrier.h: #ifdef CONFIG_SMP #define smp_mb() __smp_mb() #else #define smp_mb() barrier() #endif This has the benefit of cleaning out a bunch of duplicated ifdefs on a bunch of architectures - this patchset brings about a net reduction in LOC, more than compensa...

...lly is an artifact of interfacing with an SMP host while running an UP kernel, but since we have (at least) two users, it seems to make sense to put these APIs in a central place. In fact, smp_ barriers are stubs on !SMP, so they can be defined as follows: arch/XXX/include/asm/barrier.h: #define __smp_mb() DOSOMETHING include/asm-generic/barrier.h: #ifdef CONFIG_SMP #define smp_mb() __smp_mb() #else #define smp_mb() barrier() #endif This has the benefit of cleaning out a bunch of duplicated ifdefs on a bunch of architectures - this patchset brings about a net reduction in LOC, more than compensa...