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net: prepare (struct ubuf_info)->refcnt conversion

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In order to convert this atomic_t refcnt to refcount_t,
we need to init the refcount to one to not trigger
a 0 -> 1 transition.

This also removes one atomic operation in fast path.

v2: removed dead code in sock_zerocopy_put_abort()
as suggested by Willem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-08-31 16:48:21 -07:00 committed by David S. Miller
parent 487234cc19
commit db5bce32fb
2 changed files with 2 additions and 10 deletions
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10
net/core/skbuff.c
View File

@ -963,7 +963,7 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
uarg->len = 1;
uarg->bytelen = size;
uarg->zerocopy = 1;
atomic_set(&uarg->refcnt, 0);
atomic_set(&uarg->refcnt, 1);
sock_hold(sk);
return uarg;
@ -1005,6 +1005,7 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
uarg->len++;
uarg->bytelen = bytelen;
atomic_set(&sk->sk_zckey, ++next);
sock_zerocopy_get(uarg);
return uarg;
}
}
@ -1102,13 +1103,6 @@ void sock_zerocopy_put_abort(struct ubuf_info *uarg)
atomic_dec(&sk->sk_zckey);
uarg->len--;
/* sock_zerocopy_put expects a ref. Most sockets take one per
* skb, which is zero on abort. tcp_sendmsg holds one extra, to
* avoid an skb send inside the main loop triggering uarg free.
*/
if (sk->sk_type != SOCK_STREAM)
atomic_inc(&uarg->refcnt);
sock_zerocopy_put(uarg);
}
}

2
net/ipv4/tcp.c
View File

@ -1190,8 +1190,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
goto out_err;
}
/* skb may be freed in main loop, keep extra ref on uarg */
sock_zerocopy_get(uarg);
if (!(sk_check_csum_caps(sk) && sk->sk_route_caps & NETIF_F_SG))
uarg->zerocopy = 0;
}