linux-kernel - Re: [PATCH 3/4] pwm: Mark free pwm IDs as used in alloc

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Message-ID: <Y3SchHhvLZoRO0w6@smile.fi.intel.com>
Date:   Wed, 16 Nov 2022 10:17:08 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de
Subject: Re: [PATCH 3/4] pwm: Mark free pwm IDs as used in alloc_pwms()

On Tue, Nov 15, 2022 at 10:15:14PM +0100, Uwe Kleine-König wrote:
> alloc_pwms() only identified a free range of IDs and this range was marked
> as used only later by pwmchip_add(). Instead let alloc_pwms() already do
> the marking (which makes the function actually allocating the range and so
> justifies the function name). This way access to the allocated_pwms
> bitfield is limited to two functions only.

This change is a bit fragile in a long term. Currently we know that we have
no points of error after alloc_pwms() in ->probe(), but if somebody misses
this in the future, we became to the case where bitmap might be exhausted
(kinda resource leakage).

-- 
With Best Regards,
Andy Shevchenko