linux-kernel - Re: [PATCH] driver core: Fix double failed probing with fw

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Message-ID: <CAJZ5v0ikVbMX0R9e_=wOxKfJX5X322AipmpWy-7wVnWE7Ogc9A@mail.gmail.com>
Date:   Mon, 15 Feb 2021 15:58:52 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Saravana Kannan <saravanak@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] driver core: Fix double failed probing with fw_devlink=on

On Mon, Feb 15, 2021 at 12:16 PM Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
>
> With fw_devlink=permissive, devices are added to the deferred probe
> pending list if their driver's .probe() method returns -EPROBE_DEFER.
>
> With fw_devlink=on, devices are added to the deferred probe pending list
> if they are determined to be a consumer, which happens before their
> driver's .probe() method is called.  If the actual probe fails later
> (real failure, not -EPROBE_DEFER), the device will still be on the
> deferred probe pending list, and it will be probed again when deferred
> probing kicks in, which is futile.
>
> Fix this by explicitly removing the device from the deferred probe
> pending list in case of probe failures.
>
> Fixes: e590474768f1cc04 ("driver core: Set fw_devlink=on by default")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>

Good catch:

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
> Seen on various Renesas R-Car platforms, cfr.
> https://lore.kernel.org/linux-acpi/CAMuHMdVL-1RKJ5u-HDVA4F4w_+8yGvQQuJQBcZMsdV4yXzzfcw@mail.gmail.com
> ---
>  drivers/base/dd.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 9179825ff646f4e3..91c4181093c43709 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -639,11 +639,13 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>         case -ENXIO:
>                 pr_debug("%s: probe of %s rejects match %d\n",
>                          drv->name, dev_name(dev), ret);
> +               driver_deferred_probe_del(dev);
>                 break;
>         default:
>                 /* driver matched but the probe failed */
>                 pr_warn("%s: probe of %s failed with error %d\n",
>                         drv->name, dev_name(dev), ret);
> +               driver_deferred_probe_del(dev);
>         }
>         /*
>          * Ignore errors returned by ->probe so that the next driver can try
> --
> 2.25.1
>