Re: [PATCH -mm -next] ipc,sem: untangle RCU locking withfind_alloc_undo

[Mike Galbraith]

On Fri, 2013-04-05 at 09:21 -0400, Rik van Riel wrote: 
> On 04/05/2013 12:38 AM, Mike Galbraith wrote:
> > On Tue, 2013-03-26 at 16:00 -0400, Rik van Riel wrote:
> 
> >> The ipc semaphore code has a nasty RCU locking tangle, with both
> >> find_alloc_undo and semtimedop taking the rcu_read_lock(). The
> >> code can be cleaned up somewhat by only taking the rcu_read_lock
> >> once.
> >>
> >> There are no other callers to find_alloc_undo.
> >>
> >> This should also solve the trinity issue reported by Sasha Levin.
> >
> > I take it this is on top of the patchlet Sasha submitted?
> 
> Indeed, and all the other fixes that got submitted :)

I plugged it into my 64 core rt box and beat on it again, no stalls or
any other troubles noted.

-Mike

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