linux-kernel - Re: [PATCH 5/5] leds: trigger: netdev: use mutex instead of spinlocks

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Message-ID: <45a1f1d2-8d9b-4bc2-ba16-9dafa517fd17@lunn.ch>
Date:   Thu, 20 Apr 2023 02:27:04 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Christian Marangi <ansuelsmth@...il.com>
Cc:     Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>,
        Martin Schiller <ms@....tdt.de>, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] leds: trigger: netdev: use mutex instead of spinlocks

On Wed, Apr 19, 2023 at 11:07:43PM +0200, Christian Marangi wrote:
> Some LEDs may require to sleep while doing some operation like setting
> brightness and other cleanup.
> 
> For this reason, using a spinlock will cause a sleep under spinlock
> warning.
> 
> It should be safe to convert this to a sleepable lock since:
> - sysfs read/write can sleep
> - netdev_trig_work is a work queue and can sleep
> - netdev _trig_notify can sleep
> 
> The spinlock was used when brightness didn't support sleeping, but this
> changed and now it supported with brightness_set_blocking().
> 
> Convert to mutex lock to permit sleeping using brightness_set_blocking().
> 
> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew