[LINUX] Fix blkfront driver to check connection status to backend in

all critical circumstances.
Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
index 433d7389fe52fc09f3932fa61370aeb3083e4ca7..bb718289090706e2217bd69e521e1391814f6ebc 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
@@ -407,7 +407,8 @@ static void blkif_restart_queue(void *arg)
 {
        struct blkfront_info *info = (struct blkfront_info *)arg;
        spin_lock_irq(&blkif_io_lock);
-       kick_pending_request_queues(info);
+       if (info->connected == BLKIF_STATE_CONNECTED)
+               kick_pending_request_queues(info);
        spin_unlock_irq(&blkif_io_lock);
 }
 
@@ -595,7 +596,8 @@ void do_blkif_request(request_queue_t *rq)
                        continue;
                }
 
-               if (RING_FULL(&info->ring))
+               if (unlikely(info->connected != BLKIF_STATE_CONNECTED) ||
+                   RING_FULL(&info->ring))
                        goto wait;
 
                DPRINTK("do_blk_req %p: cmd %p, sec %lx, "
@@ -768,17 +770,17 @@ static void blkif_recover(struct blkfront_info *info)
 
        (void)xenbus_switch_state(info->xbdev, XenbusStateConnected);
 
-       /* Now safe for us to use the shared ring */
        spin_lock_irq(&blkif_io_lock);
+
+       /* Now safe for us to use the shared ring */
        info->connected = BLKIF_STATE_CONNECTED;
-       spin_unlock_irq(&blkif_io_lock);
 
        /* Send off requeued requests */
        flush_requests(info);
 
        /* Kick any other new requests queued since we resumed */
-       spin_lock_irq(&blkif_io_lock);
        kick_pending_request_queues(info);
+
        spin_unlock_irq(&blkif_io_lock);
 }