lkml.org 
[lkml]   [2014]   [Apr]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: dcache shrink list corruption?
On Wed, Apr 30, 2014 at 04:14:14PM -0700, Linus Torvalds wrote:
> On Wed, Apr 30, 2014 at 4:04 PM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > Let me go talk to the paravirt people. Maybe they don't need this, and
> > I don't know exactly *how* they use that lock pointer after the unlock
> > in the "kick waiters" part. Maybe it's all good.
>
> .. looking at current users (xen and kvm) it does in fact look all
> good. Yes, we "kick" possible waiters after the unlock, but the lock
> itself is not touched by that, it just uses the pointer to the lock as
> a way to figure out who to kick.
>
> In fact, I kind of knew that, but had forgotten. We very much depend
> on spin_unlock being safe wrt immediate deleton already: the
> "completion" code very much depends on it. It does a "spin_unlock()"
> to release the completion, and it can get reused immediately (it might
> be on the stack, it might be in some data structure that gets freed).
>
> So I'd suggest removing that whole RCU thing, because it should be
> safe to unlock something that can go away immediately. We'd have huge
> problems elsewhere if it wasn't safe.

OK, done and force-pushed. Should propagate in a few...


\
 
 \ /
  Last update: 2014-05-01 02:21    [W:0.250 / U:0.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site