Messages in this thread | | | Date | Tue, 22 Sep 2015 14:04:33 -0700 | Subject | Re: [PATCH v2] netlink: Replace rhash_portid with bound | From | Linus Torvalds <> |
| |
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
| |