From: Saeed Mahameed <saeed@kernel.org>
To: Heiner Kallweit <hkallweit1@gmail.com>,
David Miller <davem@davemloft.net>
Cc: geert+renesas@glider.be, f.fainelli@gmail.com, andrew@lunn.ch,
kuba@kernel.org, gaku.inami.xh@renesas.com,
yoshihiro.shimoda.uh@renesas.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "net: linkwatch: add check for netdevice being present to linkwatch_do_dev"
Date: Wed, 23 Sep 2020 15:42:17 -0700 [thread overview]
Message-ID: <a7ff1afd2e1fc2232103ceb9aa763064daf90212.camel@kernel.org> (raw)
In-Reply-To: <e6f50a85-aa25-5fb7-7fd2-158668d55378@gmail.com>
On Wed, 2020-09-23 at 22:44 +0200, Heiner Kallweit wrote:
> On 23.09.2020 22:15, David Miller wrote:
> > From: Heiner Kallweit <hkallweit1@gmail.com>
> > Date: Wed, 23 Sep 2020 21:58:59 +0200
> >
> > > On 23.09.2020 20:35, Saeed Mahameed wrote:
> > > > Why would a driver detach the device on ndo_stop() ?
> > > > seems like this is the bug you need to be chasing ..
> > > > which driver is doing this ?
> > > >
> > > Some drivers set the device to PCI D3hot at the end of ndo_stop()
> > > to save power (using e.g. Runtime PM). Marking the device as
> > > detached
> > > makes clear to to the net core that the device isn't accessible
> > > any
> > > longer.
> >
> > That being the case, the problem is that IFF_UP+!present is not a
> > valid netdev state.
> >
> If this combination is invalid, then netif_device_detach() should
> clear IFF_UP? At a first glance this should be sufficient to avoid
> the issue I was dealing with.
>
Feels like a work around and would conflict with the assumption that
netif_device_detach() should only be called when !IFF_UP
Maybe we need to clear IFF_UP before calling ops->ndo_stop(dev),
instead of after on __dev_close_many(). Assuming no driver is checking
IFF_UP state on its own ndo_stop(), other than this, the order
shouldn't really matter, since clearing the flag and calling ndo_stop()
should be considered as one atomic operation.
> > Is it simply the issue that, upon resume, IFF_UP is marked true
> > before
> > the device is brought out from D3hot state and thus marked as
> > present
> > again?
> >
> I can't really comment on that. The issue I was dealing with at the
> time I submitted this change was about an async linkwatch event
> (caused by powering down the PHY in ndo_stop) trying to access the
> device when it was powered down already.
next prev parent reply other threads:[~2020-09-23 22:42 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 15:02 [PATCH] Revert "net: linkwatch: add check for netdevice being present to linkwatch_do_dev" Geert Uytterhoeven
2020-09-03 21:58 ` David Miller
2020-09-10 19:20 ` David Miller
2020-09-11 6:32 ` Geert Uytterhoeven
2020-09-12 0:44 ` David Miller
2020-09-12 12:33 ` Geert Uytterhoeven
2020-09-13 1:34 ` David Miller
2020-09-14 7:40 ` Geert Uytterhoeven
2020-09-18 12:35 ` Nikolay Aleksandrov
2020-09-18 21:47 ` David Miller
2020-09-18 17:58 ` Saeed Mahameed
2020-09-18 22:10 ` David Miller
2020-09-23 11:49 ` Heiner Kallweit
2020-09-23 18:35 ` Saeed Mahameed
2020-09-23 19:58 ` Heiner Kallweit
2020-09-23 20:15 ` David Miller
2020-09-23 20:44 ` Heiner Kallweit
2020-09-23 22:42 ` Saeed Mahameed [this message]
2020-09-24 0:21 ` David Miller
2020-09-24 0:23 ` David Miller
2020-09-24 5:49 ` Saeed Mahameed
2020-09-24 16:03 ` Jakub Kicinski
2020-09-24 18:16 ` Saeed Mahameed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a7ff1afd2e1fc2232103ceb9aa763064daf90212.camel@kernel.org \
--to=saeed@kernel.org \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=f.fainelli@gmail.com \
--cc=gaku.inami.xh@renesas.com \
--cc=geert+renesas@glider.be \
--cc=hkallweit1@gmail.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=yoshihiro.shimoda.uh@renesas.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).