tcp: fix recv with flags MSG_WAITALL | MSG_PEEK

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 <[email protected]>
Reported-by: Dan Searle <[email protected]>
Signed-off-by: Sabrina Dubroca <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Sabrina Dubroca 2015-07-24 18:19:25 +02:00 • committed by David S. Miller
commit dfbafc9953
5 changed files with 14 additions and 10 deletions

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;