[IPV6]: multicast join and misc
Here is a simplified version of the patch to fix a bug in IPv6
multicasting. It:
1) adds existence check & EADDRINUSE error for regular joins
2) adds an exception for EADDRINUSE in the source-specific multicast
join (where a prior join is ok)
3) adds a missing/needed read_lock on sock_mc_list; would've raced
with destroying the socket on interface down without
4) adds a "leave group" in the (INCLUDE, empty) source filter case.
This frees unneeded socket buffer memory, but also prevents
an inappropriate interaction among the 8 socket options that
mess with this. Some would fail as if in the group when you
aren't really.
Item #4 had a locking bug in the last version of this patch; rather than
removing the idev->lock read lock only, I've simplified it to remove
all lock state in the path and treat it as a direct "leave group" call for
the (INCLUDE,empty) case it covers. Tested on an MP machine. :-)
Much thanks to HoerdtMickael <hoerdt@clarinet.u-strasbg.fr> who
reported the original bug.
Signed-off-by: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 279ab86..f3ef4c3 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -423,11 +423,12 @@
psin6 = (struct sockaddr_in6 *)&greqs.gsr_group;
retv = ipv6_sock_mc_join(sk, greqs.gsr_interface,
&psin6->sin6_addr);
- if (retv)
+ /* prior join w/ different source is ok */
+ if (retv && retv != -EADDRINUSE)
break;
omode = MCAST_INCLUDE;
add = 1;
- } else /*IP_DROP_SOURCE_MEMBERSHIP */ {
+ } else /* MCAST_LEAVE_SOURCE_GROUP */ {
omode = MCAST_INCLUDE;
add = 0;
}