linux-kernel - Re: [PATCH v11 04/33] counter: 104-quad-8: Return error when invalid mode during ceiling

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Date:   Wed, 9 Jun 2021 16:12:36 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     linux-stm32@...md-mailman.stormreply.com, kernel@...gutronix.de,
        a.fatoum@...gutronix.de, kamel.bouhara@...tlin.com,
        gwendal@...omium.org, alexandre.belloni@...tlin.com,
        david@...hnology.com, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        syednwaris@...il.com, patrick.havelange@...ensium.com,
        fabrice.gasnier@...com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, o.rempel@...gutronix.de,
        jarkko.nikula@...ux.intel.com
Subject: Re: [PATCH v11 04/33] counter: 104-quad-8: Return error when
 invalid mode during ceiling_write

On Wed,  9 Jun 2021 10:31:07 +0900
William Breathitt Gray <vilhelm.gray@...il.com> wrote:

> The 104-QUAD-8 only has two count modes where a ceiling value makes
> sense: Range Limit and Modulo-N. Outside of these two modes, setting a
> ceiling value is an invalid operation -- so let's report it as such by
> returning -EINVAL.
> 
> Fixes: fc069262261c ("counter: 104-quad-8: Add lock guards - generic interface")
> Acked-by: Syed Nayyar Waris <syednwaris@...il.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>

We seem to have some inconsistency in the driver about whether
we hold the priv->lock when calling quad8_preset_register_set()

Can we look to make that consistent?

> ---
>  drivers/counter/104-quad-8.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index 4bb9abffae48..233a3acc1377 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -714,13 +714,14 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
>  	switch (priv->count_mode[count->id]) {
>  	case 1:
>  	case 3:
> +		mutex_unlock(&priv->lock);

Probably swap this line and the next one...]

>  		quad8_preset_register_set(priv, count->id, ceiling);
> -		break;
> +		return len;
>  	}
>  
>  	mutex_unlock(&priv->lock);
>  
> -	return len;
> +	return -EINVAL;
>  }
>  
>  static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,