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Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for virt

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On Wed, Dec 30, 2015 at 03:46:46PM -0500, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@redhat.com>
> Date: Wed, 30 Dec 2015 14:58:19 +0200
> 
> > -. Patch 1 documents the __smp APIs, and explains why they are
> >    useful for virt
> 
> If virt is doing things like interacting with descriptors that are
> shared with a (potentially SMP) host, why don't we just annotate those
> specific cases?

Using a bunch of per-arch ifdefs in virtio?
That's fundamentally what we have now.

But basically the rework reduces the LOC count in kernel anyway
by moving all ifdef CONFIG_SMP hacks into asm-generic.
So why not let virt benefit?

Or do you mean wrappers for __smp_XXX that explicitly
say they are for talking to host?
E.g. pv_mb() pv_rmb() etc.
That sounds very reasonable to me.

__smp_XXX things then become an implementation detail.

> The other memory barriers in the kernel do not matter for SMP'ness
> when build UP.
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Thread

[PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for virt "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 20:40 +0100
  Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for  virt David Miller <davem@davemloft.net> - 2015-12-30 21:50 +0100
    Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for virt "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 22:40 +0100
      Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for  virt David Miller <davem@davemloft.net> - 2015-12-30 23:00 +0100
  [PATCH 17/34] arm64: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 22:50 +0100
  [PATCH 18/34] arm: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 22:50 +0100
  Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for virt "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 22:50 +0100
    Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for virt Arnd Bergmann <arnd@arndb.de> - 2015-12-30 23:50 +0100
  [PATCH 20/34] ia64: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 28/34] x86: define __smp_xxX "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 26/34] tile: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 31/34] xenbus: use __smp_xxx barriers "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 23/34] s390: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 21/34] metag: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 22/34] mips: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 24/34] sh: define __smp_xxx, fix smp_store_mb for !SMP "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 27/34] xtensa: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 25/34] sparc: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 19/34] blackfin: define __smp_xxx "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100
  [PATCH 32/34] xen/io: use __smp_xxx barriers "Michael S. Tsirkin" <mst@redhat.com> - 2015-12-30 23:00 +0100

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