xen-netback: Functional follow-up patch for grant mapping series

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

- use callback_param macro to shorten access to pending_tx_info in
  xenvif_fill_frags() and xenvif_tx_submit()
- print an error message in xenvif_idx_unmap() before panic

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

1 files changed, 19 insertions, 7 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index d3172fe0306f..cb784fe5220c 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -99,6 +99,9 @@ static inline unsigned long idx_to_kaddr(struct xenvif *vif,
         return (unsigned long)pfn_to_kaddr(idx_to_pfn(vif, idx));
 }
 
+#define callback_param(vif, pending_idx) \
+        (vif->pending_tx_info[pending_idx].callback_struct)
+
 /* Find the containing VIF's structure from a pointer in pending_tx_info array
  */
 static inline struct xenvif* ubuf_to_vif(struct ubuf_info *ubuf)
@@ -1020,12 +1023,12 @@ static void xenvif_fill_frags(struct xenvif *vif, struct sk_buff *skb)
                 /* If this is not the first frag, chain it to the previous*/
                 if (unlikely(prev_pending_idx == INVALID_PENDING_IDX))
                         skb_shinfo(skb)->destructor_arg =
-                                &vif->pending_tx_info[pending_idx].callback_struct;
+                                &callback_param(vif, pending_idx);
                 else if (likely(pending_idx != prev_pending_idx))
-                        vif->pending_tx_info[prev_pending_idx].callback_struct.ctx =
-                                &(vif->pending_tx_info[pending_idx].callback_struct);
+                        callback_param(vif, prev_pending_idx).ctx =
+                                &callback_param(vif, pending_idx);
 
-                vif->pending_tx_info[pending_idx].callback_struct.ctx = NULL;
+                callback_param(vif, pending_idx).ctx = NULL;
                 prev_pending_idx = pending_idx;
 
                 txp = &vif->pending_tx_info[pending_idx].req;
@@ -1395,13 +1398,13 @@ static int xenvif_tx_submit(struct xenvif *vif)
                 memcpy(skb->data,
                        (void *)(idx_to_kaddr(vif, pending_idx)|txp->offset),
                        data_len);
-                vif->pending_tx_info[pending_idx].callback_struct.ctx = NULL;
+                callback_param(vif, pending_idx).ctx = NULL;
                 if (data_len < txp->size) {
                         /* Append the packet payload as a fragment. */
                         txp->offset += data_len;
                         txp->size -= data_len;
                         skb_shinfo(skb)->destructor_arg =
-                                &vif->pending_tx_info[pending_idx].callback_struct;
+                                &callback_param(vif, pending_idx);
                 } else {
                         /* Schedule a response immediately. */
                         xenvif_idx_unmap(vif, pending_idx);
@@ -1681,7 +1684,16 @@ void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx)
 
         ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
                                 &vif->mmap_pages[pending_idx], 1);
-        BUG_ON(ret);
+        if (ret) {
+                netdev_err(vif->dev,
+                           "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: %x status: %d\n",
+                           ret,
+                           pending_idx,
+                           tx_unmap_op.host_addr,
+                           tx_unmap_op.handle,
+                           tx_unmap_op.status);
+                BUG();
+        }
 
         xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_OKAY);
 }