[Xen-devel] [PATCH V7 net-next 4/7] xen-netback: Correctly clean up after queue initialisation error.

["Andrew J. Bennieston" <andrew.bennieston@xxxxxxxxxx>]

From: "Andrew J. Bennieston" <andrew.bennieston@xxxxxxxxxx>

Multiple queues were introduced in the previous patch, but if the
initialisation of a queue failed, earlier queues would not be cleaned
up. This patch adds cleanup logic for this scenario, making use of code
from the regular teardown sequence.

Signed-off-by: Andrew J. Bennieston <andrew.bennieston@xxxxxxxxxx>
---
 drivers/net/xen-netback/common.h    |    1 +
 drivers/net/xen-netback/interface.c |   15 +++++++++++----
 drivers/net/xen-netback/xenbus.c    |   25 +++++++++++++++++++++++--
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 50efc29..16d6a05 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -237,6 +237,7 @@ struct xenvif *xenvif_alloc(struct device *parent,
                            unsigned int handle);
 
 int xenvif_init_queue(struct xenvif_queue *queue);
+void xenvif_deinit_queue(struct xenvif_queue *queue);
 
 int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref,
                   unsigned long rx_ring_ref, unsigned int tx_evtchn,
diff --git a/drivers/net/xen-netback/interface.c 
b/drivers/net/xen-netback/interface.c
index 0eb6941..3ded8e5 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -733,6 +733,16 @@ void xenvif_disconnect(struct xenvif *vif)
        }
 }
 
+/* Reverse the relevant parts of xenvif_init_queue().
+ * Used for queue teardown from xenvif_free(), and on the
+ * error handling paths in xenbus.c:connect().
+ */
+void xenvif_deinit_queue(struct xenvif_queue *queue)
+{
+       free_xenballooned_pages(MAX_PENDING_REQS, queue->mmap_pages);
+       netif_napi_del(&queue->napi);
+}
+
 void xenvif_free(struct xenvif *vif)
 {
        struct xenvif_queue *queue = NULL;
@@ -756,11 +766,8 @@ void xenvif_free(struct xenvif *vif)
 
        for (queue_index = 0; queue_index < num_queues; ++queue_index) {
                queue = &vif->queues[queue_index];
-
                xenvif_wait_unmap_timeout(queue, worst_case_skb_lifetime);
-               free_xenballooned_pages(MAX_PENDING_REQS, queue->mmap_pages);
-
-               netif_napi_del(&queue->napi);
+               xenvif_deinit_queue(queue);
        }
 
        /* Free the array of queues. The call below does not require
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 9632e7a..96c63dc2 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -539,14 +539,33 @@ static void connect(struct backend_info *be)
                                be->vif->dev->name, queue->id);
 
                err = xenvif_init_queue(queue);
-               if (err)
+               if (err) {
+                       /* xenvif_init_queue() cleans up after itself on
+                        * failure, but we need to clean up any previously
+                        * initialised queues. Set num_queues to i so that
+                        * earlier queues can be destroyed using the regular
+                        * disconnect logic.
+                        */
+                       rtnl_lock();
+                       netif_set_real_num_tx_queues(be->vif->dev, queue_index);
+                       rtnl_unlock();
                        goto err;
+               }
 
                queue->remaining_credit = credit_bytes;
 
                err = connect_rings(be, queue);
-               if (err)
+               if (err) {
+                       /* connect_rings() cleans up after itself on failure,
+                        * but we need to clean up after xenvif_init_queue() 
here,
+                        * and also clean up any previously initialised queues.
+                        */
+                       xenvif_deinit_queue(queue);
+                       rtnl_lock();
+                       netif_set_real_num_tx_queues(be->vif->dev, queue_index);
+                       rtnl_unlock();
                        goto err;
+               }
        }
 
        xenvif_carrier_on(be->vif);
@@ -563,6 +582,8 @@ static void connect(struct backend_info *be)
        return;
 
 err:
+       if (be->vif->dev->real_num_tx_queues > 0)
+               xenvif_disconnect(be->vif); /* Clean up existing queues */
        vfree(be->vif->queues);
        be->vif->queues = NULL;
        rtnl_lock();
-- 
1.7.10.4


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