net: add IFF_SKB_TX_SHARED flag to priv_flags

Pktgen attempts to transmit shared skbs to net devices, which can't be used by
some drivers as they keep state information in skbs.  This patch adds a flag
marking drivers as being able to handle shared skbs in their tx path.  Drivers
are defaulted to being unable to do so, but calling ether_setup enables this
flag, as 90% of the drivers calling ether_setup touch real hardware and can
handle shared skbs.  A subsequent patch will audit drivers to ensure that the
flag is set properly

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Jiri Pirko <jpirko@redhat.com>
CC: Robert Olsson <robert.olsson@its.uu.se>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 3 deletions

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index f76079cd750c..e35a6fbb8110 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -1070,7 +1070,9 @@ static ssize_t pktgen_if_write(struct file *file,
                 len = num_arg(&user_buffer[i], 10, &value);
                 if (len < 0)
                         return len;
-
+                if ((value > 0) &&
+                    (!(pkt_dev->odev->priv_flags & IFF_TX_SKB_SHARING)))
+                        return -ENOTSUPP;
                 i += len;
                 pkt_dev->clone_skb = value;
 
@@ -3555,7 +3557,6 @@ static int pktgen_add_device(struct pktgen_thread *t, const char *ifname)
         pkt_dev->min_pkt_size = ETH_ZLEN;
         pkt_dev->max_pkt_size = ETH_ZLEN;
         pkt_dev->nfrags = 0;
-        pkt_dev->clone_skb = pg_clone_skb_d;
         pkt_dev->delay = pg_delay_d;
         pkt_dev->count = pg_count_d;
         pkt_dev->sofar = 0;
@@ -3563,7 +3564,6 @@ static int pktgen_add_device(struct pktgen_thread *t, const char *ifname)
         pkt_dev->udp_src_max = 9;
         pkt_dev->udp_dst_min = 9;
         pkt_dev->udp_dst_max = 9;
-
         pkt_dev->vlan_p = 0;
         pkt_dev->vlan_cfi = 0;
         pkt_dev->vlan_id = 0xffff;
@@ -3575,6 +3575,8 @@ static int pktgen_add_device(struct pktgen_thread *t, const char *ifname)
         err = pktgen_setup_dev(pkt_dev, ifname);
         if (err)
                 goto out1;
+        if (pkt_dev->odev->priv_flags & IFF_TX_SKB_SHARING)
+                pkt_dev->clone_skb = pg_clone_skb_d;
 
         pkt_dev->entry = proc_create_data(ifname, 0600, pg_proc_dir,
                                           &pktgen_if_fops, pkt_dev);
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index b8453bd4b09c..27997d35ebd3 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -340,6 +340,7 @@ void ether_setup(struct net_device *dev)
         dev->addr_len           = ETH_ALEN;
         dev->tx_queue_len       = 1000; /* Ethernet wants good queues */
         dev->flags              = IFF_BROADCAST|IFF_MULTICAST;
+        dev->priv_flags         = IFF_TX_SKB_SHARING;
 
         memset(dev->broadcast, 0xFF, ETH_ALEN);