xen-netback: support multiple extra info fragments passed from frontend

The code does not currently support a frontend passing multiple extra info
fragments to the backend in a tx request. The xenvif_get_extras() function
handles multiple extra_info fragments but make_tx_response() assumes there
is only ever a single extra info fragment.

This patch modifies xenvif_get_extras() to pass back a count of extra
info fragments, which is then passed to make_tx_response() (after
possibly being stashed in pending_tx_info for deferred responses).

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 43 insertions, 23 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 112825200d41..f44b38846420 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -52,6 +52,7 @@ typedef unsigned int pending_ring_idx_t;
 
 struct pending_tx_info {
         struct xen_netif_tx_request req; /* tx request */
+        unsigned int extra_count;
         /* Callback data for released SKBs. The callback is always
          * xenvif_zerocopy_callback, desc contains the pending_idx, which is
          * also an index in pending_tx_info array. It is initialized in
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 61b97c34bb3b..b42f26029225 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -95,6 +95,7 @@ static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
 
 static void make_tx_response(struct xenvif_queue *queue,
                              struct xen_netif_tx_request *txp,
+                             unsigned int extra_count,
                              s8       st);
 static void push_tx_responses(struct xenvif_queue *queue);
 
@@ -696,14 +697,15 @@ void xenvif_tx_credit_callback(unsigned long data)
 }
 
 static void xenvif_tx_err(struct xenvif_queue *queue,
-                          struct xen_netif_tx_request *txp, RING_IDX end)
+                          struct xen_netif_tx_request *txp,
+                          unsigned int extra_count, RING_IDX end)
 {
         RING_IDX cons = queue->tx.req_cons;
         unsigned long flags;
 
         do {
                 spin_lock_irqsave(&queue->response_lock, flags);
-                make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR);
+                make_tx_response(queue, txp, extra_count, XEN_NETIF_RSP_ERROR);
                 push_tx_responses(queue);
                 spin_unlock_irqrestore(&queue->response_lock, flags);
                 if (cons == end)
@@ -724,6 +726,7 @@ static void xenvif_fatal_tx_err(struct xenvif *vif)
 
 static int xenvif_count_requests(struct xenvif_queue *queue,
                                  struct xen_netif_tx_request *first,
+                                 unsigned int extra_count,
                                  struct xen_netif_tx_request *txp,
                                  int work_to_do)
 {
@@ -812,7 +815,7 @@ static int xenvif_count_requests(struct xenvif_queue *queue,
         } while (more_data);
 
         if (drop_err) {
-                xenvif_tx_err(queue, first, cons + slots);
+                xenvif_tx_err(queue, first, extra_count, cons + slots);
                 return drop_err;
         }
 
@@ -827,9 +830,10 @@ struct xenvif_tx_cb {
 #define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)
 
 static inline void xenvif_tx_create_map_op(struct xenvif_queue *queue,
-                                          u16 pending_idx,
-                                          struct xen_netif_tx_request *txp,
-                                          struct gnttab_map_grant_ref *mop)
+                                           u16 pending_idx,
+                                           struct xen_netif_tx_request *txp,
+                                           unsigned int extra_count,
+                                           struct gnttab_map_grant_ref *mop)
 {
         queue->pages_to_map[mop-queue->tx_map_ops] = queue->mmap_pages[pending_idx];
         gnttab_set_map_op(mop, idx_to_kaddr(queue, pending_idx),
@@ -838,6 +842,7 @@ static inline void xenvif_tx_create_map_op(struct xenvif_queue *queue,
 
         memcpy(&queue->pending_tx_info[pending_idx].req, txp,
                sizeof(*txp));
+        queue->pending_tx_info[pending_idx].extra_count = extra_count;
 }
 
 static inline struct sk_buff *xenvif_alloc_skb(unsigned int size)
@@ -880,7 +885,7 @@ static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif_queue *que
              shinfo->nr_frags++, txp++, gop++) {
                 index = pending_index(queue->pending_cons++);
                 pending_idx = queue->pending_ring[index];
-                xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
+                xenvif_tx_create_map_op(queue, pending_idx, txp, 0, gop);
                 frag_set_pending_idx(&frags[shinfo->nr_frags], pending_idx);
         }
 
@@ -893,7 +898,8 @@ static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif_queue *que
                      shinfo->nr_frags++, txp++, gop++) {
                         index = pending_index(queue->pending_cons++);
                         pending_idx = queue->pending_ring[index];
-                        xenvif_tx_create_map_op(queue, pending_idx, txp, gop);
+                        xenvif_tx_create_map_op(queue, pending_idx, txp, 0,
+                                                gop);
                         frag_set_pending_idx(&frags[shinfo->nr_frags],
                                              pending_idx);
                 }
@@ -1095,8 +1101,9 @@ static void xenvif_fill_frags(struct xenvif_queue *queue, struct sk_buff *skb)
 }
 
 static int xenvif_get_extras(struct xenvif_queue *queue,
-                                struct xen_netif_extra_info *extras,
-                                int work_to_do)
+                             struct xen_netif_extra_info *extras,
+                             unsigned int *extra_count,
+                             int work_to_do)
 {
         struct xen_netif_extra_info extra;
         RING_IDX cons = queue->tx.req_cons;
@@ -1109,9 +1116,12 @@ static int xenvif_get_extras(struct xenvif_queue *queue,
                 }
 
                 RING_COPY_REQUEST(&queue->tx, cons, &extra);
+
+                queue->tx.req_cons = ++cons;
+                (*extra_count)++;
+
                 if (unlikely(!extra.type ||
                              extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
-                        queue->tx.req_cons = ++cons;
                         netdev_err(queue->vif->dev,
                                    "Invalid extra type: %d\n", extra.type);
                         xenvif_fatal_tx_err(queue->vif);
@@ -1119,7 +1129,6 @@ static int xenvif_get_extras(struct xenvif_queue *queue,
                 }
 
                 memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
-                queue->tx.req_cons = ++cons;
         } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
 
         return work_to_do;
@@ -1294,6 +1303,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                 struct xen_netif_tx_request txreq;
                 struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
                 struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
+                unsigned int extra_count;
                 u16 pending_idx;
                 RING_IDX idx;
                 int work_to_do;
@@ -1330,8 +1340,10 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                 queue->tx.req_cons = ++idx;
 
                 memset(extras, 0, sizeof(extras));
+                extra_count = 0;
                 if (txreq.flags & XEN_NETTXF_extra_info) {
                         work_to_do = xenvif_get_extras(queue, extras,
+                                                       &extra_count,
                                                        work_to_do);
                         idx = queue->tx.req_cons;
                         if (unlikely(work_to_do < 0))
@@ -1344,7 +1356,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                         extra = &extras[XEN_NETIF_EXTRA_TYPE_MCAST_ADD - 1];
                         ret = xenvif_mcast_add(queue->vif, extra->u.mcast.addr);
 
-                        make_tx_response(queue, &txreq,
+                        make_tx_response(queue, &txreq, extra_count,
                                          (ret == 0) ?
                                          XEN_NETIF_RSP_OKAY :
                                          XEN_NETIF_RSP_ERROR);
@@ -1358,12 +1370,14 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                         extra = &extras[XEN_NETIF_EXTRA_TYPE_MCAST_DEL - 1];
                         xenvif_mcast_del(queue->vif, extra->u.mcast.addr);
 
-                        make_tx_response(queue, &txreq, XEN_NETIF_RSP_OKAY);
+                        make_tx_response(queue, &txreq, extra_count,
+                                         XEN_NETIF_RSP_OKAY);
                         push_tx_responses(queue);
                         continue;
                 }
 
-                ret = xenvif_count_requests(queue, &txreq, txfrags, work_to_do);
+                ret = xenvif_count_requests(queue, &txreq, extra_count,
+                                            txfrags, work_to_do);
                 if (unlikely(ret < 0))
                         break;
 
@@ -1372,7 +1386,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                 if (unlikely(txreq.size < ETH_HLEN)) {
                         netdev_dbg(queue->vif->dev,
                                    "Bad packet size: %d\n", txreq.size);
-                        xenvif_tx_err(queue, &txreq, idx);
+                        xenvif_tx_err(queue, &txreq, extra_count, idx);
                         break;
                 }
 
@@ -1397,7 +1411,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                 if (unlikely(skb == NULL)) {
                         netdev_dbg(queue->vif->dev,
                                    "Can't allocate a skb in start_xmit.\n");
-                        xenvif_tx_err(queue, &txreq, idx);
+                        xenvif_tx_err(queue, &txreq, extra_count, idx);
                         break;
                 }
 
@@ -1416,7 +1430,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                         nskb = xenvif_alloc_skb(0);
                         if (unlikely(nskb == NULL)) {
                                 kfree_skb(skb);
-                                xenvif_tx_err(queue, &txreq, idx);
+                                xenvif_tx_err(queue, &txreq, extra_count, idx);
                                 if (net_ratelimit())
                                         netdev_err(queue->vif->dev,
                                                    "Can't allocate the frag_list skb.\n");
@@ -1457,13 +1471,16 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
                 if (data_len < txreq.size) {
                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
                                              pending_idx);
-                        xenvif_tx_create_map_op(queue, pending_idx, &txreq, gop);
+                        xenvif_tx_create_map_op(queue, pending_idx, &txreq,
+                                                extra_count, gop);
                         gop++;
                 } else {
                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
                                              INVALID_PENDING_IDX);
-                        memcpy(&queue->pending_tx_info[pending_idx].req, &txreq,
-                               sizeof(txreq));
+                        memcpy(&queue->pending_tx_info[pending_idx].req,
+                               &txreq, sizeof(txreq));
+                        queue->pending_tx_info[pending_idx].extra_count =
+                                extra_count;
                 }
 
                 queue->pending_cons++;
@@ -1804,7 +1821,8 @@ static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
 
         spin_lock_irqsave(&queue->response_lock, flags);
 
-        make_tx_response(queue, &pending_tx_info->req, status);
+        make_tx_response(queue, &pending_tx_info->req,
+                         pending_tx_info->extra_count, status);
 
         /* Release the pending index before pusing the Tx response so
          * its available before a new Tx request is pushed by the
@@ -1821,6 +1839,7 @@ static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
 
 static void make_tx_response(struct xenvif_queue *queue,
                              struct xen_netif_tx_request *txp,
+                             unsigned int extra_count,
                              s8       st)
 {
         RING_IDX i = queue->tx.rsp_prod_pvt;
@@ -1830,7 +1849,7 @@ static void make_tx_response(struct xenvif_queue *queue,
         resp->id     = txp->id;
         resp->status = st;
 
-        if (txp->flags & XEN_NETTXF_extra_info)
+        while (extra_count-- != 0)
                 RING_GET_RESPONSE(&queue->tx, ++i)->status = XEN_NETIF_RSP_NULL;
 
         queue->tx.rsp_prod_pvt = ++i;