Veaceslav,
It looks to me like this will leak the source filters if we are
called from ip_mc_destroy_dev(),
Even with your previous patch, you're assuming that we don't free the
ip_mc_list and so we have the
same one when we up the device, but if there are no timers running, it
looks like refcnt canl go to 0 and free
it. If we can ever free the ip_mc_list when users != 0 (or going to 0
immediately after the drop), we
have to do the ip_mc_clear_src() or leak the list. I haven't looked at
this code in years, so I'll need
to refresh my memory.
So, I'll look at that a bit more; at a minimum, I think you need
to do the clear_src
also in the destroy case. We could lose the filters and set the exclude
count to users, instead
of 1; but I like the idea of keeping the source filters across a down/up,
if we can be sure there
are no cases where we free the ip_mc_list without first freeing all the
filters.
+-DLS
Veaceslav Falico <vfalico@xxxxxxxxxx> wrote on 05/17/2011 07:37:56 AM:
> From: Veaceslav Falico <vfalico@xxxxxxxxxx>
> To: David Stevens/Beaverton/IBM@IBMUS
> Cc: David Miller <davem@xxxxxxxxxxxxx>, jmorris@xxxxxxxxx,
> kaber@xxxxxxxxx, kuznet@xxxxxxxxxxxxx, linux-kbuild@xxxxxxxxxxxxxxx,
> linux-kernel@xxxxxxxxxxxxxxx, mmarek@xxxxxxx,
> netdev@xxxxxxxxxxxxxxx, pekkas@xxxxxxxxxx, yoshfuji@xxxxxxxxxxxxxx
> Date: 05/17/2011 07:39 AM
> Subject: [PATCH v3 1/1] igmp: call ip_mc_clear_src() only when we
> have no users of ip_mc_list
>
> In igmp_group_dropped() we call ip_mc_clear_src(), which resets the
number
> of source filters per mulitcast. However, igmp_group_dropped() is also
> called on NETDEV_DOWN, NETDEV_PRE_TYPE_CHANGE and NETDEV_UNREGISTER,
which
> means that the group might get added back on NETDEV_UP, NETDEV_REGISTER
and
> NETDEV_POST_TYPE_CHANGE respectively, leaving us with broken source
> filters.
>
> To fix that, we must clear the source filters only when there are no
users
> in the ip_mc_list, i.e. in ip_mc_dec_group().
>
> Correct version of the patch.
>
> Signed-off-by: Veaceslav Falico <vfalico@xxxxxxxxxx>
> ---
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 1fd3d9c..142ca0d 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -1169,20 +1169,18 @@ static void igmp_group_dropped(struct ip_mc_list
*im)
>
> if (!in_dev->dead) {
> if (IGMP_V1_SEEN(in_dev))
> - goto done;
> + return;
> if (IGMP_V2_SEEN(in_dev)) {
> if (reporter)
> igmp_send_report(in_dev, im, IGMP_HOST_LEAVE_MESSAGE);
> - goto done;
> + return;
> }
> /* IGMPv3 */
> igmpv3_add_delrec(in_dev, im);
>
> igmp_ifc_event(in_dev);
> }
> -done:
> #endif
> - ip_mc_clear_src(im);
> }
>
> static void igmp_group_added(struct ip_mc_list *im)
> @@ -1319,6 +1317,7 @@ void ip_mc_dec_group(struct in_device *in_dev,
> __be32 addr)
> *ip = i->next_rcu;
> in_dev->mc_count--;
> igmp_group_dropped(i);
> + ip_mc_clear_src(i);
>
> if (!in_dev->dead)
> ip_rt_multicast_event(in_dev);
--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
