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authorEric Dumazet <edumazet@google.com>2019-03-26 08:34:55 -0700
committerDavid S. Miller <davem@davemloft.net>2019-03-27 13:59:02 -0700
commit4f661542a40217713f2cee0bb6678fbb30d9d367 (patch)
tree8c49f8cb2bb8e14e76b8f912ec39659dc06cb4e5
parentnet: openvswitch: Add a new action check_pkt_len (diff)
downloadlinux-dev-4f661542a40217713f2cee0bb6678fbb30d9d367.tar.xz
linux-dev-4f661542a40217713f2cee0bb6678fbb30d9d367.zip
tcp: fix zerocopy and notsent_lowat issues
My recent patch had at least three problems : 1) TX zerocopy wants notification when skb is acknowledged, thus we need to call skb_zcopy_clear() if the skb is cached into sk->sk_tx_skb_cache 2) Some applications might expect precise EPOLLOUT notifications, so we need to update sk->sk_wmem_queued and call sk_mem_uncharge() from sk_wmem_free_skb() in all cases. The SOCK_QUEUE_SHRUNK flag must also be set. 3) Reuse of saved skb should have used skb_cloned() instead of simply checking if the fast clone has been freed. Fixes: 472c2e07eef0 ("tcp: add one skb cache for tx") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/sock.h7
-rw-r--r--net/ipv4/tcp.c13
2 files changed, 7 insertions, 13 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index 577d91fb5626..7fa223278522 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1465,13 +1465,14 @@ static inline void sk_mem_uncharge(struct sock *sk, int size)
static inline void sk_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
{
+ sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
+ sk->sk_wmem_queued -= skb->truesize;
+ sk_mem_uncharge(sk, skb->truesize);
if (!sk->sk_tx_skb_cache) {
+ skb_zcopy_clear(skb, true);
sk->sk_tx_skb_cache = skb;
return;
}
- sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
- sk->sk_wmem_queued -= skb->truesize;
- sk_mem_uncharge(sk, skb->truesize);
__kfree_skb(skb);
}
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 29b94edf05f9..82bd707c0347 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -865,14 +865,9 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
{
struct sk_buff *skb;
- skb = sk->sk_tx_skb_cache;
- if (skb && !size) {
- const struct sk_buff_fclones *fclones;
-
- fclones = container_of(skb, struct sk_buff_fclones, skb1);
- if (refcount_read(&fclones->fclone_ref) == 1) {
- sk->sk_wmem_queued -= skb->truesize;
- sk_mem_uncharge(sk, skb->truesize);
+ if (likely(!size)) {
+ skb = sk->sk_tx_skb_cache;
+ if (skb && !skb_cloned(skb)) {
skb->truesize -= skb->data_len;
sk->sk_tx_skb_cache = NULL;
pskb_trim(skb, 0);
@@ -2543,8 +2538,6 @@ void tcp_write_queue_purge(struct sock *sk)
tcp_rtx_queue_purge(sk);
skb = sk->sk_tx_skb_cache;
if (skb) {
- sk->sk_wmem_queued -= skb->truesize;
- sk_mem_uncharge(sk, skb->truesize);
__kfree_skb(skb);
sk->sk_tx_skb_cache = NULL;
}