On Thu, 30 Mar 2017 08:18:34 -0500 Eric Blake <ebl...@redhat.com> wrote:
> On 03/30/2017 03:26 AM, Greg Kurz wrote:
> > If a client tries to flush the same outstanding request several times, only
> > the first flush completes. Subsequent ones keep waiting for the request
> > completion in v9fs_flush() and, therefore, leak a PDU. This will cause QEMU
> > to hang when draining active PDUs the next time the device is reset.
>
> Since this fixes a hang, is it 2.9 material?
>
Yes, definitely, I just forgot to add the for-2.9 tag :)
> >
> > Let have each flush request wake up the next one if any. The last waiter
> > frees the cancelled PDU.
> >
> > Signed-off-by: Greg Kurz <gr...@kaod.org>
> > ---
> > hw/9pfs/9p.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
>
> Reviewed-by: Eric Blake <ebl...@redhat.com>
>
> > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > index 48babce836b6..ef47a0a5ad6f 100644
> > --- a/hw/9pfs/9p.c
> > +++ b/hw/9pfs/9p.c
> > @@ -2387,8 +2387,10 @@ static void coroutine_fn v9fs_flush(void *opaque)
> > * Wait for pdu to complete.
> > */
> > qemu_co_queue_wait(&cancel_pdu->complete, NULL);
> > - cancel_pdu->cancelled = 0;
> > - pdu_free(cancel_pdu);
> > + if (!qemu_co_queue_next(&cancel_pdu->complete)) {
> > + cancel_pdu->cancelled = 0;
> > + pdu_free(cancel_pdu);
> > + }
> > }
> > pdu_complete(pdu, 7);
> > }
> >
> >
> >
>
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