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authorMichal Kubeček <mkubecek@suse.cz>2012-09-14 04:59:52 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-13 05:28:06 +0900
commit75cb41f8ea4e0fc3b6292eb8d7fcddfeafb4f718 (patch)
tree233ae41812b6325910d4adebb46150de0ff8297e /net
parent61c7891cbfa587d9cdcede0e5441c3900e862df9 (diff)
tcp: flush DMA queue before sk_wait_data if rcv_wnd is zero
[ Upstream commit 15c041759bfcd9ab0a4e43f1c16e2644977d0467 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-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 e57df66affc7..dd3af6c6ee0a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1592,8 +1592,14 @@ 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. */