net: Fix soft lockups/OOM issues w/ unix garbage collector

This is an implementation of David Miller's suggested fix in:
  https://bugzilla.redhat.com/show_bug.cgi?id=470201

It has been updated to use wait_event() instead of
wait_event_interruptible().

Paraphrasing the description from the above report, it makes sendmsg()
block while UNIX garbage collection is in progress. This avoids a
situation where child processes continue to queue new FDs over a
AF_UNIX socket to a parent which is in the exit path and running
garbage collection on these FDs. This contention can result in soft
lockups and oom-killing of unrelated processes.

Signed-off-by: dann frazier <dannf@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index c29ff1da8a18..1614d78c60ed 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -9,6 +9,7 @@
 extern void unix_inflight(struct file *fp);
 extern void unix_notinflight(struct file *fp);
 extern void unix_gc(void);
+extern void wait_for_unix_gc(void);
 
 #define UNIX_HASH_SIZE  256