Re: [PATCH] Revert "net: linkwatch: add check for netdevice being present to linkwatch_do_dev"

From: Saeed Mahameed
Date: Fri Sep 18 2020 - 13:58:54 EST


On Tue, 2020-09-01 at 17:02 +0200, Geert Uytterhoeven wrote:
> This reverts commit 124eee3f6955f7aa19b9e6ff5c9b6d37cb3d1e2c.
>
> Inami-san reported that this commit breaks bridge support in a Xen
> environment, and that reverting it fixes this.
>
> During system resume, bridge ports are no longer enabled, as that
> relies
> on the receipt of the NETDEV_CHANGE notification. This notification
> is
> not sent, as netdev_state_change() is no longer called.
>
> Note that the condition this commit intended to fix never existed
> upstream, as the patch triggering it and referenced in the commit was
> never applied upstream. Hence I can confirm s2ram on r8a73a4/ape6evm
> and sh73a0/kzm9g works fine before/after this revert.
>
> Reported-by Gaku Inami <gaku.inami.xh@xxxxxxxxxxx>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> net/core/link_watch.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/link_watch.c b/net/core/link_watch.c
> index 75431ca9300fb9c4..c24574493ecf95e6 100644
> --- a/net/core/link_watch.c
> +++ b/net/core/link_watch.c
> @@ -158,7 +158,7 @@ static void linkwatch_do_dev(struct net_device
> *dev)
> clear_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state);
>
> rfc2863_policy(dev);
> - if (dev->flags & IFF_UP && netif_device_present(dev)) {
> + if (dev->flags & IFF_UP) {

So with your issue the devices is both IFF_UP and !present ? how so ?
I think you should look into that.

I am ok with removing the "dev present" check from here just because we
shouldn't be expecting IFF_UP && !present .. such thing must be a bug
somewhere else.

> if (netif_carrier_ok(dev))
> dev_activate(dev);
> else