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authorWillem de Bruijn <willemb@google.com>2017-08-03 23:29:41 +0300
committerDavid S. Miller <davem@davemloft.net>2017-08-04 07:37:30 +0300
commit1f8b977ab32dc5d148f103326e80d9097f1cefb5 (patch)
tree1c2c09ca72dba5bd43f8b3ead791d271f075c24b /drivers/vhost
parent76851d1212c11365362525e1e2c0a18c97478e6b (diff)
downloadlinux-1f8b977ab32dc5d148f103326e80d9097f1cefb5.tar.xz
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/vhost')
-rw-r--r--drivers/vhost/net.c1
1 files changed, 1 insertions, 0 deletions
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;