linux-kernel - Re: [PATCH 1/2] Revert "net: smsc911x: Make Runtime PM handling more fine-grained"

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Date:   Thu, 16 Mar 2023 10:07:47 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc:     netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Steve Glendinning <steve.glendinning@...well.net>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] Revert "net: smsc911x: Make Runtime PM handling more fine-grained"

Hi Wolfram,

On Thu, Mar 16, 2023 at 8:46 AM Wolfram Sang
<wsa+renesas@...g-engineering.com> wrote:
> This reverts commit 1e30b8d755b81b0d1585cb22bc753e9f2124fe87. Running
> 'ifconfig' with the interface down BUGs. This is the culprit:
>
>         smsc911x_get_stats from dev_get_stats+0xe4/0xf4
>
> The above function is called with the clocks off, so register read
> fails. Enabling clocks in the above functions does not work, because it
> is called in atomic context. So, let's return to the simple and working
> PM we had before.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>

Thanks for your patch!

In sh_eth this was fixed differently, by adding a check for
mdp->is_opened to sh_eth_get_stats() [1].
I believe the modern way would be to add a check for netif_running()
instead.

Would adding such a check to smsc911x_get_stats() work for you, too?

[1] 7fa2955ff70ce453 ("sh_eth: Fix sleeping function called from
invalid context")

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds