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

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Date:   Fri, 18 Sep 2020 15:10:55 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     saeed@...nel.org
Cc:     geert+renesas@...der.be, hkallweit1@...il.com,
        f.fainelli@...il.com, andrew@...n.ch, kuba@...nel.org,
        gaku.inami.xh@...esas.com, yoshihiro.shimoda.uh@...esas.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Revert "net: linkwatch: add check for netdevice being
 present to linkwatch_do_dev"

From: Saeed Mahameed <saeed@...nel.org>
Date: Fri, 18 Sep 2020 10:58:49 -0700

> On Tue, 2020-09-01 at 17:02 +0200, Geert Uytterhoeven wrote:
>> @@ -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.

Indeed, this is why I just asked in another email why a link change event
is firing for a device which hasn't fully resumed and marked itself as
"present" yet.

More and more I think this is a driver or PHY layer bug.