net: fec: correct the counting of XDP sent frames

[ Upstream commit 26312c685ae0bca61e06ac75ee158b1e69546415 ]

In the current xdp_xmit implementation, if any single frame fails to
transmit due to insufficient buffer descriptors, the function nevertheless
reports success in sending all frames. This results in erroneously
indicating that frames were transmitted when in fact they were dropped.

This patch fixes the issue by ensureing the return value properly
indicates the actual number of frames successfully transmitted, rather than
potentially reporting success for all frames when some could not transmit.

Fixes: 6d6b39f180b8 ("net: fec: add initial XDP support")
Signed-off-by: Gagandeep Singh <g.singh@nxp.com>
Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 2341597408d129cda9979f6dddb4db759f3a87fa..5fd3b413198279cb816c37948bf0b3840c8fc886 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -3737,7 +3737,8 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep,
        entries_free = fec_enet_get_free_txdesc_num(txq);
        if (entries_free < MAX_SKB_FRAGS + 1) {
                netdev_err(fep->netdev, "NOT enough BD for SG!\n");
-               return NETDEV_TX_OK;
+               xdp_return_frame(frame);
+               return NETDEV_TX_BUSY;
        }
 
        /* Fill in a Tx ring entry */
@@ -3795,6 +3796,7 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
        struct fec_enet_private *fep = netdev_priv(dev);
        struct fec_enet_priv_tx_q *txq;
        int cpu = smp_processor_id();
+       unsigned int sent_frames = 0;
        struct netdev_queue *nq;
        unsigned int queue;
        int i;
@@ -3805,8 +3807,11 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
 
        __netif_tx_lock(nq, cpu);
 
-       for (i = 0; i < num_frames; i++)
-               fec_enet_txq_xmit_frame(fep, txq, frames[i]);
+       for (i = 0; i < num_frames; i++) {
+               if (fec_enet_txq_xmit_frame(fep, txq, frames[i]) != 0)
+                       break;
+               sent_frames++;
+       }
 
        /* Make sure the update to bdp and tx_skbuff are performed. */
        wmb();
@@ -3816,7 +3821,7 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
 
        __netif_tx_unlock(nq);
 
-       return num_frames;
+       return sent_frames;
 }
 
 static const struct net_device_ops fec_netdev_ops = {