search for: barrier

...oes this (conceptually): #ifdef CONFIG_SMP smp_mb(); #else mb(); #endif Similarly, Xen calls mb() when it's not doing any MMIO at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just sw...

...oes this (conceptually): #ifdef CONFIG_SMP smp_mb(); #else mb(); #endif Similarly, Xen calls mb() when it's not doing any MMIO at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just sw...

...oes this (conceptually): #ifdef CONFIG_SMP smp_mb(); #else mb(); #endif Similarly, Xen calls mb() when it's not doing any MMIO at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just sw...

...oes this (conceptually): #ifdef CONFIG_SMP smp_mb(); #else mb(); #endif Similarly, Xen calls mb() when it's not doing any MMIO at all. Of course it's wrong in the sense that it's suboptimal. What we would really like is to have, on UP, exactly the same barrier as on SMP. This is because a UP guest can run on an SMP host. But Linux doesn't provide this ability: if CONFIG_SMP is not defined is optimizes most barriers out to a compiler barrier. Consider for example x86: what we want is xchg (NOT mfence - there's no real IO going on here - just sw...

...afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc: Linux 4.4 (2016-01-10 15:01:32 -0800) are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to 43e361f23c49dbddf74f56ddf6cdd85c5dbff6da: checkpatch: add virt barriers (2016-01-12 20:47:08 +0200) ---------------------------------------------------------------- virtio: barrier rework+fixes This adds a new kind of barrier, and reworks virtio and xen to use it. Plus some fixes here and there. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> ---------...

...afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc: Linux 4.4 (2016-01-10 15:01:32 -0800) are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to 43e361f23c49dbddf74f56ddf6cdd85c5dbff6da: checkpatch: add virt barriers (2016-01-12 20:47:08 +0200) ---------------------------------------------------------------- virtio: barrier rework+fixes This adds a new kind of barrier, and reworks virtio and xen to use it. Plus some fixes here and there. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> ---------...

Changes since v2: - extended checkpatch tests for barriers, and added patches teaching it to warn about incorrect usage of barriers (__smp_xxx barriers are for use by asm-generic code only), should help prevent misuse by arch code to address comments by Russell King - patched more instances of xen to use virt_ barriers as suggested by Stefano Stabe...

Changes since v2: - extended checkpatch tests for barriers, and added patches teaching it to warn about incorrect usage of barriers (__smp_xxx barriers are for use by asm-generic code only), should help prevent misuse by arch code to address comments by Russell King - patched more instances of xen to use virt_ barriers as suggested by Stefano Stabe...

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 CONFIG_SMP, they can not > use the existing fence() macro since that is defined differently be...

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 CONFIG_SMP, they can not > use the existing fence() macro since that is defined differently be...

...t; Linux 4.4 (2016-01-10 15:01:32 -0800) > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus > > for you to fetch changes up to 43e361f23c49dbddf74f56ddf6cdd85c5dbff6da: > > checkpatch: add virt barriers (2016-01-12 20:47:08 +0200) > > ---------------------------------------------------------------- > virtio: barrier rework+fixes > > This adds a new kind of barrier, and reworks virtio and xen > to use it. > Plus some fixes here and there. > > Signed-off-by: Michael S....

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This replaces the checkpatch patches in my series arch: barrier cleanup + barriers for virt and will be included in the pull request including the series. changes from v3: rename smp_barrier_stem...

As part of memory barrier cleanup, this patchset extends checkpatch to make it easier to stop incorrect memory barrier usage. This replaces the checkpatch patches in my series arch: barrier cleanup + barriers for virt and will be included in the pull request including the series. changes from v3: rename smp_barrier_stem...

...e ("locking/arch: Rename set_mb() to smp_store_mb()") > it was made clear that the context of this call (and thus set_mb) > is strictly for CPU ordering, as opposed to IO. As such all archs > should use the smp variant of mb(), respecting the semantics and > saving a mandatory barrier on UP. > > Signed-off-by: Davidlohr Bueso <dbueso at suse.de> > Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org> > Cc: <linux-arch at vger.kernel.org> > Cc: Andrew Morton <akpm at linux-foundation.org> > Cc: Benjamin Herrenschmidt <benh a...

...e ("locking/arch: Rename set_mb() to smp_store_mb()") > it was made clear that the context of this call (and thus set_mb) > is strictly for CPU ordering, as opposed to IO. As such all archs > should use the smp variant of mb(), respecting the semantics and > saving a mandatory barrier on UP. > > Signed-off-by: Davidlohr Bueso <dbueso at suse.de> > Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org> > Cc: <linux-arch at vger.kernel.org> > Cc: Andrew Morton <akpm at linux-foundation.org> > Cc: Benjamin Herrenschmidt <benh a...

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): checkpatch.pl: add missing memory barri...

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): checkpatch.pl: add missing memory barri...

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. Changes from v2: catch optional\s* before () in barriers rewrit...

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. Changes from v2: catch optional\s* before () in barriers rewrit...

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 asm-generic/barriers.h > > Note: smp_mb, smp_rmb and smp_wmb are defined as full barriers > unconditionally on this architecture. > > Signed-off-by: Michael...