The dst's do disappear but the net device does not. A better solution
is to only hold reference to dst's net device ONLY if it is not a
loopback device. In the case of the loopback device, we want to do
only a "put" on it and skip the "hold".
Updating the patch below:
---
net/core/dst.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/core/dst.c b/net/core/dst.c
index 7e45593..f63027e 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -433,12 +433,11 @@ static void dst_ifdown(struct dst_entry *dst,
struct net_device *dev,
dst->input = dst_discard;
dst->output = dst_discard_out;
} else {
- if (dst->dev == dev_net(dst->dev)->loopback_dev)
- dst->dev = init_net.loopback_dev;
- else
+ if (dst->dev != dev_net(dst->dev)->loopback_dev) {
dst->dev = dev_net(dst->dev)->loopback_dev;
+ dev_hold(dst->dev);
+ }
- dev_hold(dst->dev);
dev_put(dev);
}
}
--
1.8.3.1
On Thu, Sep 8, 2016 at 3:16 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> On Thu, 2016-09-08 at 15:12 -0700, Jojy Varghese wrote:
>> Hi Eric/Lance
>>
>> Thanks for taking time to look at the patch. The problem in dst.c's
>> "dst_ifdown" is that it will never do an actual "dev_put" on the
>> loopback net device. This results in the loopback net device to be
>> alive even when the dst goes away.
>
> Sure, but the dst themselves should disappear, and thus release their
> dst->dev reference.
>
> Something is missing.
>
> loopback device is only used when we remove one device from the system,
> but namespace (and loopback device) is still around.
>
>
>
--
Jojy G Varghese
