[PATCH] vhost: Avoid that vhost_work_flush() locks up

[Bart Van Assche <bvanassche@acm.org>]

Wake up work->done waiters even if the TIF_NEED_RESCHED task flag
has been set. This patch fixes a regression introduced in commit
d550dda (kernel v3.4).

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=60505
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Asias He <asias@redhat.com>
Cc: Nadav Har'El <nyh@math.technion.ac.il>
Cc: Abel Gordon <abelg@il.ibm.com>
Cc: <stable@vger.kernel.org> # v3.4+
---
 drivers/vhost/vhost.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 60aa5ad..cd544ae 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -227,8 +227,16 @@ static int vhost_worker(void *data)
 		if (work) {
 			__set_current_state(TASK_RUNNING);
 			work->fn(work);
-			if (need_resched())
+			if (need_resched()) {
+				spin_lock_irq(&dev->work_lock);
+				work->done_seq = seq;
+				if (work->flushing)
+					wake_up_all(&work->done);
+				spin_unlock_irq(&dev->work_lock);
+
+				work = NULL;
 				schedule();
+			}
 		} else
 			schedule();
 
-- 
1.7.10.4