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.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Glenn Enright <glenn@xxxxxxxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
drivers/block/xen-blkback/blkback.c | 3 ---
drivers/block/xen-blkback/xenbus.c | 1 -
2 files changed, 4 deletions(-)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 726c32e35db9..6b14c509f3c7 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -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;
}
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 4d2f57fa35da..1dc0ff5ed912 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -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
--
2.12.0