Commit 5bbbfdf6 authored Nov 17, 2015 by Junichi Nomura Committed by Mike Snitzer Nov 17, 2015

dm: fix ioctl retry termination with signal



dm-mpath retries ioctl, when no path is readily available and the device
is configured to queue I/O in such a case. If you want to stop the retry
before multipathd decides to turn off queueing mode, you could send
signal for the process to exit from the loop.

However the check of fatal signal has not carried along when commit
6c182cd8 ("dm mpath: fix ioctl deadlock when no paths") moved the
loop from dm-mpath to dm core. As a result, we can't terminate such
a process in the retry loop.

Easy reproducer of the situation is:

  # dmsetup create mp --table '0 1024 multipath 0 0 0 0'
  # dmsetup message mp 0 'queue_if_no_path'
  # sg_inq /dev/mapper/mp

then you should be able to terminate sg_inq by pressing Ctrl+C.

Fixes: 6c182cd8 ("dm mpath: fix ioctl deadlock when no paths")
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org

parent 172c2386

drivers/md/dm-mpath.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1562,7 +1562,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti,

		spin_unlock_irqrestore(&m->lock, flags);

		if (r == -ENOTCONN && !fatal_signal_pending(current)) {
		if (r == -ENOTCONN) {
		spin_lock_irqsave(&m->lock, flags);
		if (!m->current_pg) {
		/* Path status changed, redo selection */

drivers/md/dm.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -591,7 +591,7 @@ retry:

		out:
		dm_put_live_table(md, *srcu_idx);
		if (r == -ENOTCONN) {
		if (r == -ENOTCONN && !fatal_signal_pending(current)) {
		msleep(10);
		goto retry;
		}

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