xen/blkfront: realloc ring info in blkif_resume

Need to reallocate ring info in the resume path, because info->rinfo was freed
in blkif_free(). And 'multi-queue-max-queues' backend reports may have been
changed.

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Reported-and-Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 8a8dc91..83eb9e6 100644 (file)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1873,6 +1873,43 @@ again:
        return err;
 }
 
+static int negotiate_mq(struct blkfront_info *info)
+{
+       unsigned int backend_max_queues = 0;
+       int err;
+       unsigned int i;
+
+       BUG_ON(info->nr_rings);
+
+       /* Check if backend supports multiple queues. */
+       err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
+                          "multi-queue-max-queues", "%u", &backend_max_queues);
+       if (err < 0)
+               backend_max_queues = 1;
+
+       info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
+       /* We need at least one ring. */
+       if (!info->nr_rings)
+               info->nr_rings = 1;
+
+       info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
+       if (!info->rinfo) {
+               xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
+               return -ENOMEM;
+       }
+
+       for (i = 0; i < info->nr_rings; i++) {
+               struct blkfront_ring_info *rinfo;
+
+               rinfo = &info->rinfo[i];
+               INIT_LIST_HEAD(&rinfo->indirect_pages);
+               INIT_LIST_HEAD(&rinfo->grants);
+               rinfo->dev_info = info;
+               INIT_WORK(&rinfo->work, blkif_restart_queue);
+               spin_lock_init(&rinfo->ring_lock);
+       }
+       return 0;
+}
 /**
  * Entry point to this code when a new device is created.  Allocate the basic
  * structures and the ring buffer for communication with the backend, and
@@ -1883,9 +1920,7 @@ static int blkfront_probe(struct xenbus_device *dev,
                          const struct xenbus_device_id *id)
 {
        int err, vdevice;
-       unsigned int r_index;
        struct blkfront_info *info;
-       unsigned int backend_max_queues = 0;
 
        /* FIXME: Use dynamic device id if this is not set. */
        err = xenbus_scanf(XBT_NIL, dev->nodename,
@@ -1936,33 +1971,10 @@ static int blkfront_probe(struct xenbus_device *dev,
        }
 
        info->xbdev = dev;
-       /* Check if backend supports multiple queues. */
-       err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-                          "multi-queue-max-queues", "%u", &backend_max_queues);
-       if (err < 0)
-               backend_max_queues = 1;
-
-       info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
-       /* We need at least one ring. */
-       if (!info->nr_rings)
-               info->nr_rings = 1;
-
-       info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
-       if (!info->rinfo) {
-               xenbus_dev_fatal(dev, -ENOMEM, "allocating ring_info structure");
+       err = negotiate_mq(info);
+       if (err) {
                kfree(info);
-               return -ENOMEM;
-       }
-
-       for (r_index = 0; r_index < info->nr_rings; r_index++) {
-               struct blkfront_ring_info *rinfo;
-
-               rinfo = &info->rinfo[r_index];
-               INIT_LIST_HEAD(&rinfo->indirect_pages);
-               INIT_LIST_HEAD(&rinfo->grants);
-               rinfo->dev_info = info;
-               INIT_WORK(&rinfo->work, blkif_restart_queue);
-               spin_lock_init(&rinfo->ring_lock);
+               return err;
        }
 
        mutex_init(&info->mutex);
@@ -2123,12 +2135,16 @@ static int blkif_recover(struct blkfront_info *info)
 static int blkfront_resume(struct xenbus_device *dev)
 {
        struct blkfront_info *info = dev_get_drvdata(&dev->dev);
-       int err;
+       int err = 0;
 
        dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
 
        blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
 
+       err = negotiate_mq(info);
+       if (err)
+               return err;
+
        err = talk_to_blkback(dev, info);
 
        /*