Re: [PATCH v2 22/32] s390: define __smp_xxx

On Mon, Jan 04, 2016 at 02:45:25PM +0100, Peter Zijlstra wrote: > On Thu, Dec 31, 2015 at 09:08:38PM +0200, Michael S. Tsirkin wrote: > > This defines __smp_xxx barriers for s390, > > for use by virtualization. > > > > Some smp_xxx barriers are removed as they are > > defined correctly by

Re: [PATCH v2 06/32] s390: reuse asm-generic/barrier.h

On Mon, Jan 04, 2016 at 02:20:42PM +0100, Peter Zijlstra wrote: > On Thu, Dec 31, 2015 at 09:06:30PM +0200, Michael S. Tsirkin wrote: > > On s390 read_barrier_depends, smp_read_barrier_depends > > smp_store_mb(), smp_mb__before_atomic and smp_mb__after_atomic match the > > asm-generic variants

Re: [PATCH v2 17/32] arm: define __smp_xxx

On Mon, Jan 04, 2016 at 02:36:58PM +0100, Peter Zijlstra wrote: > On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote: > > On Sat, Jan 02, 2016 at 11:24:38AM +, Russell King - ARM Linux wrote: > > > > My only concern is that it gives people an additional handle onto a > > >

[PATCH 0/3] checkpatch: handling of memory barriers

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This applies on top of my series arch: barrier cleanup + barriers for virt and will be included in the next version of the series. Michael S. Tsirkin (3):

Re: [PATCH v2 34/34] xen/io: use virt_xxx barriers

On Thu, 31 Dec 2015, Michael S. Tsirkin wrote: > include/xen/interface/io/ring.h uses > full memory barriers to communicate with the other side. > > For guests compiled with CONFIG_SMP, smp_wmb and smp_mb > would be sufficient, so mb() and wmb() here are only needed if > a non-SMP guest runs on

Re: [PATCH v2 33/34] xenbus: use virt_xxx barriers

On Thu, 31 Dec 2015, Michael S. Tsirkin wrote: > drivers/xen/xenbus/xenbus_comms.c uses > full memory barriers to communicate with the other side. > > For guests compiled with CONFIG_SMP, smp_wmb and smp_mb > would be sufficient, so mb() and wmb() here are only needed if > a non-SMP guest runs on

Re: [Xen-devel] [PATCH v2 34/34] xen/io: use virt_xxx barriers

On 31/12/15 19:10, Michael S. Tsirkin wrote: > include/xen/interface/io/ring.h uses > full memory barriers to communicate with the other side. > > For guests compiled with CONFIG_SMP, smp_wmb and smp_mb > would be sufficient, so mb() and wmb() here are only needed if > a non-SMP guest runs on an

[PATCH 1/3] checkpatch.pl: add missing memory barriers

SMP-only barriers were missing in checkpatch.pl Refactor code slightly to make adding more variants easier. Signed-off-by: Michael S. Tsirkin --- scripts/checkpatch.pl | 9 - 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/scripts/checkpatch.pl

Re: [PATCH v2 20/32] metag: define __smp_xxx

Hi Michael, On Thu, Dec 31, 2015 at 09:08:22PM +0200, Michael S. Tsirkin wrote: > This defines __smp_xxx barriers for metag, > for use by virtualization. > > smp_xxx barriers are removed as they are > defined correctly by asm-generic/barriers.h > > Note: as __smp_XX macros should not depend on

Re: [PATCH v2 17/32] arm: define __smp_xxx

On Sun, Jan 03, 2016 at 11:12:44AM +0200, Michael S. Tsirkin wrote: > On Sat, Jan 02, 2016 at 11:24:38AM +, 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 __* > >

Re: [PATCH v2 06/32] s390: reuse asm-generic/barrier.h

On Thu, Dec 31, 2015 at 09:06:30PM +0200, Michael S. Tsirkin wrote: > On s390 read_barrier_depends, smp_read_barrier_depends > smp_store_mb(), smp_mb__before_atomic and smp_mb__after_atomic match the > asm-generic variants exactly. Drop the local definitions and pull in > asm-generic/barrier.h

Re: [PATCH v2 20/32] metag: define __smp_xxx

On Thu, Dec 31, 2015 at 09:08:22PM +0200, Michael S. Tsirkin wrote: > +#ifdef CONFIG_SMP > +#define fence() metag_fence() > +#else > +#define fence() do { } while (0) > #endif James, it strikes me as odd that fence() is a no-op instead of a barrier() for UP, can you verify/explain?

Re: [PATCH v2 31/32] sh: support a 2-byte smp_store_mb

On Thu, Dec 31, 2015 at 09:09:47PM +0200, Michael S. Tsirkin wrote: > At the moment, xchg on sh only supports 4 and 1 byte values, so using it > from smp_store_mb means attempts to store a 2 byte value using this > macro fail. > > And happens to be exactly what virtio drivers want to do. > >

Re: [PATCH v2 33/34] xenbus: use virt_xxx barriers

On Thu, Dec 31, 2015 at 09:10:01PM +0200, Michael S. Tsirkin wrote: > drivers/xen/xenbus/xenbus_comms.c uses > full memory barriers to communicate with the other side. > > For guests compiled with CONFIG_SMP, smp_wmb and smp_mb > would be sufficient, so mb() and wmb() here are only needed if > a

Re: [PATCH v2 06/32] s390: reuse asm-generic/barrier.h

On Mon, 4 Jan 2016 14:20:42 +0100 Peter Zijlstra wrote: > On Thu, Dec 31, 2015 at 09:06:30PM +0200, Michael S. Tsirkin wrote: > > On s390 read_barrier_depends, smp_read_barrier_depends > > smp_store_mb(), smp_mb__before_atomic and smp_mb__after_atomic match the > >

Re: [PATCH v2 20/32] metag: define __smp_xxx

Hi Peter, On Mon, Jan 04, 2016 at 02:41:28PM +0100, Peter Zijlstra wrote: > On Thu, Dec 31, 2015 at 09:08:22PM +0200, Michael S. Tsirkin wrote: > > +#ifdef CONFIG_SMP > > +#define fence() metag_fence() > > +#else > > +#define fence()do { } while (0) > > #endif > > James, it strikes

Re: [PATCH v2 20/32] metag: define __smp_xxx

On Mon, Jan 04, 2016 at 03:25:58PM +, James Hogan wrote: > It is used along with the metag specific __global_lock1() (global > voluntary lock between hw threads) whenever a write is performed, and by > smp_mb/smp_rmb to try to catch other cases, but I've never been > confident this fixes every

Re: [PATCH v2 20/32] metag: define __smp_xxx

On Mon, Jan 04, 2016 at 04:30:36PM +0100, Peter Zijlstra wrote: > On Mon, Jan 04, 2016 at 03:25:58PM +, James Hogan wrote: > > It is used along with the metag specific __global_lock1() (global > > voluntary lock between hw threads) whenever a write is performed, and by > > smp_mb/smp_rmb to

Re: [PATCH 1/3] checkpatch.pl: add missing memory barriers

On Mon, Jan 04, 2016 at 08:07:40AM -0800, Joe Perches wrote: > On Mon, 2016-01-04 at 13:36 +0200, Michael S. Tsirkin wrote: > > + my $all_barriers = join('|', (@barriers, @smp_barriers)); > > + > > + if ($line =~ /\b($all_barriers)\(/) { > > It would be better to use

Re: [PATCH 1/3] checkpatch.pl: add missing memory barriers

On Mon, 2016-01-04 at 16:11 +, Russell King - ARM Linux wrote: > On Mon, Jan 04, 2016 at 08:07:40AM -0800, Joe Perches wrote: > > On Mon, 2016-01-04 at 13:36 +0200, Michael S. Tsirkin wrote: > > > + my $all_barriers = join('|', (@barriers, @smp_barriers)); > > > + > > > + if