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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