linux-kernel - Re: [PATCH v2 1/2] driver core: clear deferred probe reason on probe retry

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Date:   Mon, 22 Mar 2021 09:18:06 +0100
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Ahmad Fatoum <a.fatoum@...gutronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Mark Brown <broonie@...nel.org>
Cc:     kernel@...gutronix.de, andy.shevchenko@...il.com,
        stable@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] driver core: clear deferred probe reason on
 probe retry

Hi Ahmad,

W dniu 19.03.2021 o 12:04, Ahmad Fatoum pisze:
> When retrying a deferred probe, any old defer reason string should be
> discarded. Otherwise, if the probe is deferred again at a different spot,
> but without setting a message, the now incorrect probe reason will remain.
>
> 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.
>
> Cc: stable@...nel.org
> Fixes: d090b70ede02 ("driver core: add deferring probe reason to devices_deferred property")
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Ahmad Fatoum <a.fatoum@...gutronix.de>


Reviewed-by: Andrzej Hajda <a.hajda@...sung.com>


Regards

Andrzej


> ---
> v1 -> v2:
>   - reworded commit message (Andy)
>   - collected Andy's Reviewed-by
> ---
>   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