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Re: [PATCH v2] netlink: Replace rhash_portid with bound

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On Tue, Sep 22, 2015 at 1:36 PM, Bjørn Mork <bjorn@mork.no> wrote:
>
> http://download.intel.com/design/archives/processors/pro/docs/24268935.pdf
>
> Says "NoFix" for erratas 66 and 92.

Yeah, 66 and 92 do look like they could cause the apparent ordering of
accesses to be violated. That said, both of them <i>seem</i> to be
"processor had exclusive access to line A, and gave it away but ended
up still reading now-stale data".

And that's not what we use "smp_wmb()" or "smp_rmb()" to protect
against. If we did a write and then wanted to do an ordered read, we'd
use smp_mb(), which always does that barrier.

So I don't know whether either of those really merit our PPRO
workaround. Cache coherency is hard.

There's also errata 41, which looks like it would be a bad situation.

                 Linus
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Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-22 18:20 +0200
  Re: [PATCH v2] netlink: Replace rhash_portid with bound Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 20:50 +0200
    Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-22 21:00 +0200
      Re: [PATCH v2] netlink: Replace rhash_portid with bound Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 21:30 +0200
        Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-22 22:00 +0200
          Re: [PATCH v2] netlink: Replace rhash_portid with bound Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 22:10 +0200
            Re: [PATCH v2] netlink: Replace rhash_portid with bound Bjørn Mork <bjorn@mork.no> - 2015-09-22 22:50 +0200
              Re: [PATCH v2] netlink: Replace rhash_portid with bound Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 23:10 +0200
  Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-23 08:20 +0200
    Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-23 18:00 +0200
      Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-24 04:40 +0200
        Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-24 04:50 +0200
          Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-24 05:00 +0200
            Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-24 05:10 +0200
              Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-24 05:30 +0200
                Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-24 05:30 +0200
                Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-24 05:40 +0200
                Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-24 05:50 +0200
                Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-24 05:50 +0200
                Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-24 05:50 +0200
                Re: [PATCH v2] netlink: Replace rhash_portid with bound Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-24 05:50 +0200

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