[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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



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?


Tested against an HVM debian guest with a QCOW2 image as system disk, and
as a hot-plugged/unplgged secondary disk.

And I've run an osstest flight with the patch.

Thanks,


Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.