This is a note to let you know that I've just added the patch titled
xen/blkback: don't use xen_blkif_get() in xen-blkback kthread
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-blkback-don-t-use-xen_blkif_get-in-xen-blkback-kthread.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a24fa22ce22ae302b3bf8f7008896d52d5d57b8d Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@xxxxxxxx>
Date: Thu, 18 May 2017 17:28:49 +0200
Subject: xen/blkback: don't use xen_blkif_get() in xen-blkback kthread
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Juergen Gross <jgross@xxxxxxxx>
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@xxxxxxxx>
Tested-by: Steven Haigh <netwiz@xxxxxxxxx>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/xen-blkback/blkback.c | 3 ---
drivers/block/xen-blkback/xenbus.c | 1 -
2 files changed, 4 deletions(-)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -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;
}
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -221,7 +221,6 @@ static int xen_blkif_disconnect(struct x
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
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-4.4/xen-blkback-don-t-free-be-structure-too-early.patch
queue-4.4/xen-blkback-don-t-use-xen_blkif_get-in-xen-blkback-kthread.patch