Re: [Xen-devel] [PATCH] xen-bus/block: explicitly assign event channels to an AioContext

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Jan 29, 2020 at 10:22:14PM +0000, Julien Grall wrote:
> Hi Anthony,
> 
> On 19/12/2019 17:11, Anthony PERARD wrote:
> > On Mon, Dec 16, 2019 at 02:34:51PM +0000, Paul Durrant wrote:
> > > It is not safe to close an event channel from the QEMU main thread when
> > > that channel's poller is running in IOThread context.
> > > 
> > > This patch adds a new xen_device_set_event_channel_context() function
> > > to explicitly assign the channel AioContext, and modifies
> > > xen_device_bind_event_channel() to initially assign the channel's poller
> > > to the QEMU main thread context. The code in xen-block's dataplane is
> > > then modified to assign the channel to IOThread context during
> > > xen_block_dataplane_start() and de-assign it during in
> > > xen_block_dataplane_stop(), such that the channel is always assigned
> > > back to main thread context before it is closed. aio_set_fd_handler()
> > > already deals with all the necessary synchronization when moving an fd
> > > between AioContext-s so no extra code is needed to manage this.
> > > 
> > > Reported-by: Julien Grall <jgrall@xxxxxxxxxx>
> > > Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
> > 
> > Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> 
> I can't find the patch in QEMU upstream. Are we missing any ack/review for
> this patch?

No, I just need to prepare a pull request. It's in my list of patch for
upstream, so there will be a pull request at some point before the next
QEMU release.

Cheers,

-- 
Anthony PERARD

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