3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiri Bohac <jbohac@xxxxxxx> [ Upstream commit 01462405f0c093b2f8dfddafcadcda6c9e4c5cdf ] This fixes an old regression introduced by commit b0d0d915 (ipx: remove the BKL). When a recvmsg syscall blocks waiting for new data, no data can be sent on the same socket with sendmsg because ipx_recvmsg() sleeps with the socket locked. This breaks mars-nwe (NetWare emulator): - the ncpserv process reads the request using recvmsg - ncpserv forks and spawns nwconn - ncpserv calls a (blocking) recvmsg and waits for new requests - nwconn deadlocks in sendmsg on the same socket Commit b0d0d915 has simply replaced BKL locking with lock_sock/release_sock. Unlike now, BKL got unlocked while sleeping, so a blocking recvmsg did not block a concurrent sendmsg. Only keep the socket locked while actually working with the socket data and release it prior to calling skb_recv_datagram(). Signed-off-by: Jiri Bohac <jbohac@xxxxxxx> Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipx/af_ipx.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/net/ipx/af_ipx.c +++ b/net/ipx/af_ipx.c @@ -1763,6 +1763,7 @@ static int ipx_recvmsg(struct kiocb *ioc struct ipxhdr *ipx = NULL; struct sk_buff *skb; int copied, rc; + bool locked = true; lock_sock(sk); /* put the autobinding in */ @@ -1789,6 +1790,8 @@ static int ipx_recvmsg(struct kiocb *ioc if (sock_flag(sk, SOCK_ZAPPED)) goto out; + release_sock(sk); + locked = false; skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT, flags & MSG_DONTWAIT, &rc); if (!skb) @@ -1822,7 +1825,8 @@ static int ipx_recvmsg(struct kiocb *ioc out_free: skb_free_datagram(sk, skb); out: - release_sock(sk); + if (locked) + release_sock(sk); return rc; } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html