[Xen-devel] [PATCH net-next 3/8] xen-netback: support multiple extra info segments passed from frontend

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

The code does not currently allow a frontend to pass multiple extra info
segments to the backend in a tx request. A subsequent patch in this series
needs this functionality so it is added here, without any other
modification, for better bisectability.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 drivers/net/xen-netback/common.h  |  1 +
 drivers/net/xen-netback/netback.c | 27 +++++++++++++++++++--------
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 136ace1..ce40bd7 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -51,6 +51,7 @@ typedef unsigned int pending_ring_idx_t;
 
 struct pending_tx_info {
        struct xen_netif_tx_request req; /* tx request */
+       unsigned int extra_count; /* Number of extras following the request */
        /* 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 27c6779..9f0c9f5 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -95,7 +95,8 @@ 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,
-                            s8       st);
+                            s8       st,
+                            unsigned int extra_count);
 static void push_tx_responses(struct xenvif_queue *queue);
 
 static inline int tx_work_todo(struct xenvif_queue *queue);
@@ -646,7 +647,7 @@ static void xenvif_tx_err(struct xenvif_queue *queue,
 
        do {
                spin_lock_irqsave(&queue->response_lock, flags);
-               make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR);
+               make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR, 0);
                push_tx_responses(queue);
                spin_unlock_irqrestore(&queue->response_lock, flags);
                if (cons == end)
@@ -1292,7 +1293,8 @@ static void xenvif_tx_build_gops(struct xenvif_queue 
*queue,
                        make_tx_response(queue, &txreq,
                                         (ret == 0) ?
                                         XEN_NETIF_RSP_OKAY :
-                                        XEN_NETIF_RSP_ERROR);
+                                        XEN_NETIF_RSP_ERROR,
+                                        1);
                        push_tx_responses(queue);
                        continue;
                }
@@ -1303,7 +1305,7 @@ 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, XEN_NETIF_RSP_OKAY, 1);
                        push_tx_responses(queue);
                        continue;
                }
@@ -1411,6 +1413,9 @@ static void xenvif_tx_build_gops(struct xenvif_queue 
*queue,
                               sizeof(txreq));
                }
 
+               if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type)
+                       queue->pending_tx_info[pending_idx].extra_count++;
+
                queue->pending_cons++;
 
                gop = xenvif_get_requests(queue, skb, txfrags, gop,
@@ -1749,7 +1754,9 @@ 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, status,
+                        pending_tx_info->extra_count);
+       memset(pending_tx_info, 0, sizeof(*pending_tx_info));
 
        /* Release the pending index before pusing the Tx response so
         * its available before a new Tx request is pushed by the
@@ -1766,7 +1773,8 @@ 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,
-                            s8       st)
+                            s8       st,
+                            unsigned int extra_count)
 {
        RING_IDX i = queue->tx.rsp_prod_pvt;
        struct xen_netif_tx_response *resp;
@@ -1775,8 +1783,11 @@ static void make_tx_response(struct xenvif_queue *queue,
        resp->id     = txp->id;
        resp->status = st;
 
-       if (txp->flags & XEN_NETTXF_extra_info)
-               RING_GET_RESPONSE(&queue->tx, ++i)->status = XEN_NETIF_RSP_NULL;
+       WARN_ON(!(txp->flags & XEN_NETTXF_extra_info) != !extra_count);
+
+       while (extra_count-- != 0)
+               RING_GET_RESPONSE(&queue->tx, ++i)->status =
+                       XEN_NETIF_RSP_NULL;
 
        queue->tx.rsp_prod_pvt = ++i;
 }
-- 
2.1.4


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