Sorry last patch was just the delta over my original patch. Here is
the complete patch:
---
net/core/dst.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/core/dst.c b/net/core/dst.c
index a1656e3..f63027e 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -433,8 +433,11 @@ static void dst_ifdown(struct dst_entry *dst,
struct net_device *dev,
dst->input = dst_discard;
dst->output = dst_discard_out;
} else {
- dst->dev = dev_net(dst->dev)->loopback_dev;
- dev_hold(dst->dev);
+ if (dst->dev != dev_net(dst->dev)->loopback_dev) {
+ dst->dev = dev_net(dst->dev)->loopback_dev;
+ dev_hold(dst->dev);
+ }
+
dev_put(dev);
}
}
--
1.8.3.1
On Thu, Sep 8, 2016 at 4:16 PM, Jojy Varghese <jojy.vargh...@gmail.com> wrote:
> 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
--
Jojy G Varghese
