diff options
| author | Michal Kubeček <mkubecek@suse.cz> | 2012-09-14 04:59:52 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-09-19 16:07:58 -0400 |
| commit | 15c041759bfcd9ab0a4e43f1c16e2644977d0467 (patch) | |
| tree | c530b3395136fc4c29ff022200adf5d948ce5bc8 /net | |
| parent | dbd6b11e15a2f96030da17dbeda943a8a98ee990 (diff) | |
| download | lwn-15c041759bfcd9ab0a4e43f1c16e2644977d0467.tar.gz lwn-15c041759bfcd9ab0a4e43f1c16e2644977d0467.zip | |
tcp: flush DMA queue before sk_wait_data if rcv_wnd is zero
If recv() syscall is called for a TCP socket so that
- IOAT DMA is used
- MSG_WAITALL flag is used
- requested length is bigger than sk_rcvbuf
- enough data has already arrived to bring rcv_wnd to zero
then when tcp_recvmsg() gets to calling sk_wait_data(), receive
window can be still zero while sk_async_wait_queue exhausts
enough space to keep it zero. As this queue isn't cleaned until
the tcp_service_net_dma() call, sk_wait_data() cannot receive
any data and blocks forever.
If zero receive window and non-empty sk_async_wait_queue is
detected before calling sk_wait_data(), process the queue first.
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 2109ff4a1daf..bf9a8ab29459 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1762,8 +1762,14 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, } #ifdef CONFIG_NET_DMA - if (tp->ucopy.dma_chan) - dma_async_memcpy_issue_pending(tp->ucopy.dma_chan); + if (tp->ucopy.dma_chan) { + if (tp->rcv_wnd == 0 && + !skb_queue_empty(&sk->sk_async_wait_queue)) { + tcp_service_net_dma(sk, true); + tcp_cleanup_rbuf(sk, copied); + } else + dma_async_memcpy_issue_pending(tp->ucopy.dma_chan); + } #endif if (copied >= target) { /* Do not sleep, just process backlog. */ |