linux-kernel - Re: [PATCH 21/22] Input: rotary_encoder - use guard notation when acquiring mutex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f74cb5d9-3489-4aef-a43e-0989132cf344@gmail.com>
Date: Wed, 4 Sep 2024 21:32:35 +0200
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>, linux-input@...r.kernel.org
Cc: Michael Hennerich <michael.hennerich@...log.com>,
 Ville Syrjala <syrjala@....fi>,
 Support Opensource <support.opensource@...semi.com>,
 Eddie James <eajames@...ux.ibm.com>, Andrey Moiseev <o2g.org.ru@...il.com>,
 Hans de Goede <hdegoede@...hat.com>, Jeff LaBundy <jeff@...undy.com>,
 linux-kernel@...r.kernel.org,
 Javier Carrasco Cruz <javier.carrasco.cruz@...il.com>
Subject: Re: [PATCH 21/22] Input: rotary_encoder - use guard notation when
 acquiring mutex

On 04/09/2024 06:49, Dmitry Torokhov wrote:
> Using guard notation makes the code more compact and error handling
> more robust by ensuring that mutexes are released in all code paths
> when control leaves critical section.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
>  drivers/input/misc/rotary_encoder.c | 23 ++++++++---------------
>  1 file changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
> index 6628fe540834..52761da9f999 100644
> --- a/drivers/input/misc/rotary_encoder.c
> +++ b/drivers/input/misc/rotary_encoder.c
> @@ -113,7 +113,7 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
>  	struct rotary_encoder *encoder = dev_id;
>  	unsigned int state;
>  
> -	mutex_lock(&encoder->access_mutex);
> +	guard(mutex)(&encoder->access_mutex);
>  
>  	state = rotary_encoder_get_state(encoder);
>  
> @@ -136,8 +136,6 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
>  		break;
>  	}
>  
> -	mutex_unlock(&encoder->access_mutex);
> -
>  	return IRQ_HANDLED;
>  }
>  
> @@ -146,7 +144,7 @@ static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
>  	struct rotary_encoder *encoder = dev_id;
>  	unsigned int state;
>  
> -	mutex_lock(&encoder->access_mutex);
> +	guard(mutex)(&encoder->access_mutex);
>  
>  	state = rotary_encoder_get_state(encoder);
>  
> @@ -159,8 +157,6 @@ static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
>  		}
>  	}
>  
> -	mutex_unlock(&encoder->access_mutex);
> -
>  	return IRQ_HANDLED;
>  }
>  
> @@ -169,22 +165,19 @@ static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
>  	struct rotary_encoder *encoder = dev_id;
>  	unsigned int state;
>  
> -	mutex_lock(&encoder->access_mutex);
> +	guard(mutex)(&encoder->access_mutex);
>  
>  	state = rotary_encoder_get_state(encoder);
>  
> -	if ((encoder->last_stable + 1) % 4 == state)
> +	if ((encoder->last_stable + 1) % 4 == state) {
>  		encoder->dir = 1;
> -	else if (encoder->last_stable == (state + 1) % 4)
> +		rotary_encoder_report_event(encoder);
> +	} else if (encoder->last_stable == (state + 1) % 4) {
>  		encoder->dir = -1;
> -	else
> -		goto out;
> -
> -	rotary_encoder_report_event(encoder);
> +		rotary_encoder_report_event(encoder);
> +	}
>  
> -out:
>  	encoder->last_stable = state;
> -	mutex_unlock(&encoder->access_mutex);
>  
>  	return IRQ_HANDLED;
>  }

Reviewed-by: Javier Carrasco <javier.carrasco.cruz@...il.com>