Re: [PATCH v2] counter: fix an IS_ERR() vs NULL bug

[William Breathitt Gray <vilhelm.gray@gmail.com>]

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On Tue, Jan 11, 2022 at 08:32:43PM +0300, Dan Carpenter wrote:
> There are 8 callers for devm_counter_alloc() and they all check for NULL
> instead of error pointers.  I think NULL is the better thing to return
> for allocation functions so update counter_alloc() and devm_counter_alloc()
> to return NULL instead of error pointers.
> 
> Fixes: c18e2760308e ("counter: Provide alternative counter registration functions")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>

> ---
> v2: make additional style changes
> 
>  drivers/counter/counter-core.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c
> index 7e0957eea094..869894b74741 100644
> --- a/drivers/counter/counter-core.c
> +++ b/drivers/counter/counter-core.c
> @@ -90,10 +90,8 @@ struct counter_device *counter_alloc(size_t sizeof_priv)
>  	int err;
>  
>  	ch = kzalloc(sizeof(*ch) + sizeof_priv, GFP_KERNEL);
> -	if (!ch) {
> -		err = -ENOMEM;
> -		goto err_alloc_ch;
> -	}
> +	if (!ch)
> +		return NULL;
>  
>  	counter = &ch->counter;
>  	dev = &counter->dev;
> @@ -123,9 +121,8 @@ struct counter_device *counter_alloc(size_t sizeof_priv)
>  err_ida_alloc:
>  
>  	kfree(ch);
> -err_alloc_ch:
>  
> -	return ERR_PTR(err);
> +	return NULL;
>  }
>  EXPORT_SYMBOL_GPL(counter_alloc);
>  
> @@ -208,12 +205,12 @@ struct counter_device *devm_counter_alloc(struct device *dev, size_t sizeof_priv
>  	int err;
>  
>  	counter = counter_alloc(sizeof_priv);
> -	if (IS_ERR(counter))
> -		return counter;
> +	if (!counter)
> +		return NULL;
>  
>  	err = devm_add_action_or_reset(dev, devm_counter_put, counter);
>  	if (err < 0)
> -		return ERR_PTR(err);
> +		return NULL;
>  
>  	return counter;
>  }
> -- 
> 2.20.1
> 

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