linux-kernel - Re: [PATCH] leds: tca6507: fix error handling of using fwnode_property_read

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Date:   Mon, 3 Apr 2023 17:23:55 +0200
From:   Pavel Machek <pavel@....cz>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Marek Behún <kabel@...nel.org>,
        Lee Jones <lee@...nel.org>, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org,
        NeilBrown <neilb@...e.de>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] leds: tca6507: fix error handling of using
 fwnode_property_read_string

On Sun 2023-04-02 13:12:59, H. Nikolaus Schaller wrote:
> Commit 96f524105b9c ("leds: tca6507: use fwnode API instead of OF")
> 
> changed to fwnode API but did not take into account that a missing property
> "linux,default-trigger" now seems to return an error and as a side effect
> sets value to -1. This seems to be different from of_get_property() which
> always returned NULL in any case of error.
> 
> Neglecting this side-effect leads to
> 
> [   11.201965] Unable to handle kernel paging request at virtual address ffffffff when read
> 
> in the strcmp() of led_trigger_set_default() if there is no led-trigger
> defined in the DTS.
> 
> I don't know if this was recently introduced somewhere in the fwnode lib
> or if the effect was missed in initial testing. Anyways it seems to be a
> bug to ignore the error return value of an optional value here in the
> driver.
> 
> Fixes: 96f524105b9c ("leds: tca6507: use fwnode API instead of OF")
> Cc: Marek Behún <kabel@...nel.org>
> Cc: NeilBrown <neilb@...e.de>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>

Acked-by: Pavel Machek <pavel@....cz>

BR,							Pavel
-- 
People of Russia, stop Putin before his war on Ukraine escalates.

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