xen-netback: Non-functional follow-up patch for grant mapping series

Ian made some late comments about the grant mapping series, I incorporated the
non-functional outcomes into this patch:

- typo fixes in a comment of xenvif_free(), and add another one there as well
- typo fix for comment of rx_drain_timeout_msecs
- remove stale comment before calling xenvif_grant_handle_reset()

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 3 deletions

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index e71fb1ac5c4d..cdc298e3b747 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -574,15 +574,15 @@ void xenvif_disconnect(struct xenvif *vif)
 void xenvif_free(struct xenvif *vif)
 {
         int i, unmap_timeout = 0;
-        /* Here we want to avoid timeout messages if an skb can be legitimatly
-         * stucked somewhere else. Realisticly this could be an another vif's
+        /* Here we want to avoid timeout messages if an skb can be legitimately
+         * stuck somewhere else. Realistically this could be an another vif's
          * internal or QDisc queue. That another vif also has this
          * rx_drain_timeout_msecs timeout, but the timer only ditches the
          * internal queue. After that, the QDisc queue can put in worst case
          * XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS skbs into that another vif's
          * internal queue, so we need several rounds of such timeouts until we
          * can be sure that no another vif should have skb's from us. We are
-         * not sending more skb's, so newly stucked packets are not interesting
+         * not sending more skb's, so newly stuck packets are not interesting
          * for us here.
          */
         unsigned int worst_case_skb_lifetime = (rx_drain_timeout_msecs/1000) *
@@ -597,6 +597,13 @@ void xenvif_free(struct xenvif *vif)
                                 netdev_err(vif->dev,
                                            "Page still granted! Index: %x\n",
                                            i);
+                        /* If there are still unmapped pages, reset the loop to
+                         * start checking again. We shouldn't exit here until
+                         * dealloc thread and NAPI instance release all the
+                         * pages. If a kernel bug causes the skbs to stall
+                         * somewhere, the interface cannot be brought down
+                         * properly.
+                         */
                         i = -1;
                 }
         }