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

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commit a24fa22ce22ae302b3bf8f7008896d52d5d57b8d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Juergen Gross 2017-05-18 17:28:49 +02:00 • committed by Greg Kroah-Hartman
parent 53f5772477
commit 366f50133b
2 changed files with 0 additions and 4 deletions
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3
drivers/block/xen-blkback/blkback.c
View file

@ -595,8 +595,6 @@ int xen_blkif_schedule(void *arg)
unsigned long timeout;
int ret;
xen_blkif_get(blkif);
while (!kthread_should_stop()) {
if (try_to_freeze())
continue;
@ -650,7 +648,6 @@ purge_gnt_list:
print_stats(blkif);
blkif->xenblkd = NULL;
xen_blkif_put(blkif);
return 0;
}

1
drivers/block/xen-blkback/xenbus.c
View file

@ -221,7 +221,6 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
if (blkif->xenblkd) {
kthread_stop(blkif->xenblkd);
wake_up(&blkif->shutdown_wq);
blkif->xenblkd = NULL;
}
/* The above kthread_stop() guarantees that at this point we