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authorMichal Kubeček <mkubecek@suse.cz>2012-09-14 04:59:52 (GMT)
committerDavid S. Miller <davem@davemloft.net>2012-09-19 20:07:58 (GMT)
commit15c041759bfcd9ab0a4e43f1c16e2644977d0467 (patch)
treec530b3395136fc4c29ff022200adf5d948ce5bc8 /net/ipv4
parentdbd6b11e15a2f96030da17dbeda943a8a98ee990 (diff)
downloadlinux-15c041759bfcd9ab0a4e43f1c16e2644977d0467.tar.xz
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/ipv4')
-rw-r--r--net/ipv4/tcp.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2109ff4..bf9a8ab 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. */