linux-kernel - Re: [PATCH 1/2] driver core: clear deferred probe reason on probe retry

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Message-ID: <CAHp75VcFy1=p6x0nj6wC-tK5ph6Puvx++8aVALLC0WTrkoN8AA@mail.gmail.com>
Date:   Thu, 18 Mar 2021 14:47:58 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Sascha Hauer <kernel@...gutronix.de>, stable@...nel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] driver core: clear deferred probe reason on probe retry

On Thu, Mar 18, 2021 at 9:39 AM Ahmad Fatoum <a.fatoum@...gutronix.de> wrote:
>
> When retrying a deferred probe, any old defer reason string should be
> discarded. Otherwise, if probe is deferred again at a different spot,

probe -> the probe

> but without setting a message, a now incorrect probe reason will remain.

a now incorrect -> now the incorrect

> This was observed with the i.MX I2C driver, which ultimately failed
> to probe due to lack of the GPIO driver. The probe defer for GPIO
> doesn't record a message, but a previous probe defer to clock_get did.
> This had the effect that /sys/kernel/debug/devices_deferred listed
> a misleading probe deferral reason.

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Cc: stable@...nel.org
> Fixes: d090b70ede02 ("driver core: add deferring probe reason to devices_deferred property")
> Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>
> ---
>  drivers/base/dd.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 9179825ff646..e2cf3b29123e 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -97,6 +97,9 @@ static void deferred_probe_work_func(struct work_struct *work)
>
>                 get_device(dev);
>
> +               kfree(dev->p->deferred_probe_reason);
> +               dev->p->deferred_probe_reason = NULL;
> +
>                 /*
>                  * Drop the mutex while probing each device; the probe path may
>                  * manipulate the deferred list
> --
> 2.29.2
>


-- 
With Best Regards,
Andy Shevchenko