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tcp: fix recv with flags MSG_WAITALL | MSG_PEEK

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Currently, tcp_recvmsg enters a busy loop in sk_wait_data if called
with flags = MSG_WAITALL | MSG_PEEK.

sk_wait_data waits for sk_receive_queue not empty, but in this case,
the receive queue is not empty, but does not contain any skb that we
can use.

Add a "last skb seen on receive queue" argument to sk_wait_data, so
that it sleeps until the receive queue has new skbs.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=99461
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=18493
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1205258
Reported-by: Enrico Scholz <rh-bugzilla@ensc.de>
Reported-by: Dan Searle <dan@censornet.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sabrina Dubroca
2015-07-24 18:19:25 +02:00
committed by David S. Miller
parent 3d3af88592
commit dfbafc9953
5 changed files with 14 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
net/ipv4/tcp.c
View File

@@ -780,7 +780,7 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
ret = -EAGAIN;
break;
}
sk_wait_data(sk, &timeo);
sk_wait_data(sk, &timeo, NULL);
if (signal_pending(current)) {
ret = sock_intr_errno(timeo);
break;
@@ -1575,7 +1575,7 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
int target; /* Read at least this many bytes */
long timeo;
struct task_struct *user_recv = NULL;
struct sk_buff *skb;
struct sk_buff *skb, *last;
u32 urg_hole = 0;
if (unlikely(flags & MSG_ERRQUEUE))
@@ -1635,7 +1635,9 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
/* Next get a buffer. */
last = skb_peek_tail(&sk->sk_receive_queue);
skb_queue_walk(&sk->sk_receive_queue, skb) {
last = skb;
/* Now that we have two receive queues this
* shouldn't happen.
*/
@@ -1754,8 +1756,9 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
/* Do not sleep, just process backlog. */
release_sock(sk);
lock_sock(sk);
} else
sk_wait_data(sk, &timeo);
} else {
sk_wait_data(sk, &timeo, last);
}
if (user_recv) {
int chunk;