linux/net/ipx
Jiri Bohac 01462405f0 ipx: fix locking regression in ipx_sendmsg and ipx_recvmsg
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@suse.cz>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-20 22:57:03 -05:00
..
af_ipx.c ipx: fix locking regression in ipx_sendmsg and ipx_recvmsg 2014-11-20 22:57:03 -05:00
ipx_proc.c net: proc_fs: trivial: print UIDs as unsigned int 2013-08-15 14:37:46 -07:00
ipx_route.c net: Split sk_no_check into sk_no_check_{rx,tx} 2014-05-23 16:28:53 -04:00
Kconfig ipx: remove the BKL 2011-03-05 10:55:58 +01:00
Makefile ipx: move peII functions 2012-07-19 10:48:00 -07:00
pe2.c ipx: move peII functions 2012-07-19 10:48:00 -07:00
sysctl_net_ipx.c net: Convert all sysctl registrations to register_net_sysctl 2012-04-20 21:22:30 -04:00