Chas,
It's been a while since I've looked at that call path in detail, but
if memory
serves, when the interface is going down, the thread that is doing the
"down" acquires
a reference to the in_dev, so nothing in the chain should actually have the
last
reference-- the in_dev is freed when the last reference is removed in the
thread that
caused all of it.
But there is a bug in starting the timer from igmp_group_dropped()
after the
ifc timer has been deleted-- I now see your point there. ip_mc_down()
clears the list
of deleted records that would be reported, but the timer would be started,
anyway.
Below is a patch that I think might do the trick, for your case, but
I need to
check on possible races with group drops while doing a down-- if so, it'll
need some
reworking to handle those.
I'm concerned about checking IFF_UP in the same place as it does the
all hosts group because a) I'm not sure the flag is cleared at that point
and b) I'm
not sure in the v2 case if it currently sends (immediately) leave messages
that with
the check might not be sent. A little investigation would turn up the
answers to those, but
a patch that doesn't affect existing v2 behaviour (unless it's incorrect
:-)) would be better.
Meantime, if you get a chance to try this patch, please let me know
if it doesn't
work. I'll do some testing on my own, but haven't done any yet.
+-DLS
(in-line for viewing, attached for applying, since my mailer messes with
whitespace)
*** linux-2.5.73F4/net/ipv4/igmp.c 2003-06-23 13:26:02.000000000 -0700
--- linux-2.5.73F5/net/ipv4/igmp.c 2003-07-07 12:54:57.000000000 -0700
***************
*** 1196,1202 ****
--- 1196,1206 ----
ASSERT_RTNL();
+ for (i=in_dev->mc_list; i; i=i->next)
+ igmp_group_dropped(i);
+
#ifdef CONFIG_IP_MULTICAST
+ igmpv3_clear_delrec(in_dev);
in_dev->mr_ifc_count = 0;
if (del_timer(&in_dev->mr_ifc_timer))
__in_dev_put(in_dev);
***************
*** 1205,1217 ****
__in_dev_put(in_dev);
#endif
- for (i=in_dev->mc_list; i; i=i->next)
- igmp_group_dropped(i);
-
- #ifdef CONFIG_IP_MULTICAST
- igmpv3_clear_delrec(in_dev);
- #endif
-
ip_mc_dec_group(in_dev, IGMP_ALL_HOSTS);
}
--- 1209,1214 ----
(See attached file: igmp.patch)Attachment:
igmp.patch
Description: Binary data
