Commit a24fa22c authored May 18, 2017 by Juergen Gross Committed by Konrad Rzeszutek Wilk Jun 13, 2017

xen/blkback: don't use xen_blkif_get() in xen-blkback kthread



There is no need to use xen_blkif_get()/xen_blkif_put() in the kthread
of xen-blkback. Thread stopping is synchronous and using the blkif
reference counting in the kthread will avoid to ever let the reference
count drop to zero at the end of an I/O running concurrent to
disconnecting and multiple rings.

Setting ring->xenblkd to NULL after stopping the kthread isn't needed
as the kthread does this already.

Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

parent 71df1d7c

drivers/block/xen-blkback/blkback.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -609,8 +609,6 @@ int xen_blkif_schedule(void *arg)
		unsigned long timeout;
		int ret;

		xen_blkif_get(blkif);

		set_freezable();
		while (!kthread_should_stop()) {
		if (try_to_freeze())
		@@ -665,7 +663,6 @@ int xen_blkif_schedule(void *arg)
		print_stats(ring);

		ring->xenblkd = NULL;
		xen_blkif_put(blkif);

		return 0;
		}

drivers/block/xen-blkback/xenbus.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -255,7 +255,6 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
		if (ring->xenblkd) {
		kthread_stop(ring->xenblkd);
		wake_up(&ring->shutdown_wq);
		ring->xenblkd = NULL;
		}

		/* The above kthread_stop() guarantees that at this point we