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authorWillem de Bruijn <willemb@google.com>2017-08-03 16:29:41 -0400
committerDavid S. Miller <davem@davemloft.net>2017-08-03 21:37:30 -0700
commit1f8b977ab32dc5d148f103326e80d9097f1cefb5 (patch)
tree1c2c09ca72dba5bd43f8b3ead791d271f075c24b /drivers
parent76851d1212c11365362525e1e2c0a18c97478e6b (diff)
sock: enable MSG_ZEROCOPY
Prepare the datapath for refcounted ubuf_info. Clone ubuf_info with skb_zerocopy_clone() wherever needed due to skb split, merge, resize or clone. Split skb_orphan_frags into two variants. The split, merge, .. paths support reference counted zerocopy buffers, so do not do a deep copy. Add skb_orphan_frags_rx for paths that may loop packets to receive sockets. That is not allowed, as it may cause unbounded latency. Deep copy all zerocopy copy buffers, ref-counted or not, in this path. The exact locations to modify were chosen by exhaustively searching through all code that might modify skb_frag references and/or the the SKBTX_DEV_ZEROCOPY tx_flags bit. The changes err on the safe side, in two ways. (1) legacy ubuf_info paths virtio and tap are not modified. They keep a 1:1 ubuf_info to sk_buff relationship. Calls to skb_orphan_frags still call skb_copy_ubufs and thus copy frags in this case. (2) not all copies deep in the stack are addressed yet. skb_shift, skb_split and skb_try_coalesce can be refined to avoid copying. These are not in the hot path and this patch is hairy enough as is, so that is left for future refinement. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/tun.c2
-rw-r--r--drivers/vhost/net.c1
2 files changed, 2 insertions, 1 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 68add55f8460..d21510d47aa2 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -892,7 +892,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
sk_filter(tfile->socket.sk, skb))
goto drop;
- if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
+ if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
goto drop;
skb_tx_timestamp(skb);
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 06d044862e58..ba08b78ed630 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -533,6 +533,7 @@ static void handle_tx(struct vhost_net *net)
ubuf->callback = vhost_zerocopy_callback;
ubuf->ctx = nvq->ubufs;
ubuf->desc = nvq->upend_idx;
+ atomic_set(&ubuf->refcnt, 1);
msg.msg_control = ubuf;
msg.msg_controllen = sizeof(ubuf);
ubufs = nvq->ubufs;