Re: [PATCH v4 5/5] x86: drop mfence in favor of lock+addl

2016-01-27 Thread Michael S. Tsirkin
On Wed, Jan 27, 2016 at 09:37:45AM -0800, Linus Torvalds wrote: > On Wed, Jan 27, 2016 at 7:10 AM, Michael S. Tsirkin 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.

Re: [PATCH v4 5/5] x86: drop mfence in favor of lock+addl

2016-01-27 Thread Linus Torvalds
On Wed, Jan 27, 2016 at 7:10 AM, Michael S. Tsirkin 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?