[Xen-devel] [PATCH net-next v3 2/3] xen-netback: Non-functional follow-up patch for grant mapping series

[Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
v2:
- expand commit message and split this into 2 patch
- fix typos

v3: Change the subject

diff --git a/drivers/net/xen-netback/interface.c 
b/drivers/net/xen-netback/interface.c
index e71fb1a..cdc298e 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;
                }
        }
diff --git a/drivers/net/xen-netback/netback.c 
b/drivers/net/xen-netback/netback.c
index f5c440b..684c10b 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -56,7 +56,7 @@ bool separate_tx_rx_irq = 1;
 module_param(separate_tx_rx_irq, bool, 0644);
 
 /* When guest ring is filled up, qdisc queues the packets for us, but we have
- * to timeout them, otherwise other guests' packets can get stucked there
+ * to timeout them, otherwise other guests' packets can get stuck there
  */
 unsigned int rx_drain_timeout_msecs = 10000;
 module_param(rx_drain_timeout_msecs, uint, 0444);
@@ -1545,7 +1545,6 @@ static inline void xenvif_tx_dealloc_action(struct xenvif 
*vif)
                                            idx_to_kaddr(vif, pending_idx),
                                            GNTMAP_host_map,
                                            vif->grant_tx_handle[pending_idx]);
-                       /* Btw. already unmapped? */
                        xenvif_grant_handle_reset(vif, pending_idx);
                        ++gop;
                }
@@ -1678,7 +1677,6 @@ void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx)
                            idx_to_kaddr(vif, pending_idx),
                            GNTMAP_host_map,
                            vif->grant_tx_handle[pending_idx]);
-       /* Btw. already unmapped? */
        xenvif_grant_handle_reset(vif, pending_idx);
 
        ret = gnttab_unmap_refs(&tx_unmap_op, NULL,

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