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

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Message-ID: <Y3Tt3IvCchpZotk9@smile.fi.intel.com>
Date:   Wed, 16 Nov 2022 16:04:12 +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.

Let's assume that developers will be cautious about properly freeing allocated
resources.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
>  drivers/pwm/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index 2338119a09d8..b43b24bd3c9f 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -51,6 +51,8 @@ static int alloc_pwms(unsigned int count)
>  	if (start + count > MAX_PWMS)
>  		return -ENOSPC;
>  
> +	bitmap_set(allocated_pwms, start, count);
> +
>  	return start;
>  }
>  
> @@ -297,8 +299,6 @@ int pwmchip_add(struct pwm_chip *chip)
>  		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
>  	}
>  
> -	bitmap_set(allocated_pwms, chip->base, chip->npwm);
> -
>  	INIT_LIST_HEAD(&chip->list);
>  	list_add(&chip->list, &pwm_chips);
>  
> -- 
> 2.38.1
> 

-- 
With Best Regards,
Andy Shevchenko