Commit f1c6bb2c authored Apr 15, 2014 by Jeff Layton

locks: allow __break_lease to sleep even when break_time is 0



A fl->fl_break_time of 0 has a special meaning to the lease break code
that basically means "never break the lease". knfsd uses this to ensure
that leases don't disappear out from under it.

Unfortunately, the code in __break_lease can end up passing this value
to wait_event_interruptible as a timeout, which prevents it from going
to sleep at all. This makes __break_lease to spin in a tight loop and
causes soft lockups.

Fix this by ensuring that we pass a minimum value of 1 as a timeout
instead.

Cc: <stable@vger.kernel.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Reported-by: Terry Barnaby <terry1@beam.ltd.uk>
Signed-off-by: Jeff Layton <jlayton@redhat.com>

parent 55101e2d

fs/locks.c

+3 −4

Original line number	Original line	Diff line number	Diff line
	@@ -1391,11 +1391,10 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)

	restart:		restart:
	break_time = flock->fl_break_time;		break_time = flock->fl_break_time;
	if (break_time != 0) {		if (break_time != 0)
	break_time -= jiffies;		break_time -= jiffies;
	if (break_time == 0)		if (break_time == 0)
	break_time++;		break_time++;
	}
	locks_insert_block(flock, new_fl);		locks_insert_block(flock, new_fl);
	spin_unlock(&inode->i_lock);		spin_unlock(&inode->i_lock);
	error = wait_event_interruptible_timeout(new_fl->fl_wait,		error = wait_event_interruptible_timeout(new_fl->fl_wait,

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