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

[Rik van Riel]

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 hit rcu stall banging on patch set in rt with 60 synchronized core
> executive model if I let it run long enough, fwtw)

What are you using to trigger an rcu stall?

> > Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> > Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>

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