linux-kernel - Re: [PATCH v1 1/2] devres: Switch to use dev_err

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Message-ID: <e2f49a1f1877550c4ca733bbca26949836d4fef1.camel@redhat.com>
Date: Thu, 29 Feb 2024 09:52:34 +0100
From: Philipp Stanner <pstanner@...hat.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Rasmus Villemoes
	 <linux@...musvillemoes.dk>, pstanner@...hat.com
Subject: Re: [PATCH v1 1/2] devres: Switch to use dev_err_probe() for
 unification

On Tue, 2024-02-27 at 19:58 +0200, Andy Shevchenko wrote:
> The devm_*() APIs are supposed to be called during the ->probe()
> stage.
> Many drivers (especially new ones) has switched to use

has -> have

> dev_err_probe()
> for error messaging for the sake of unification. Let's do the same in
> the devres APIs.

No objections on principle. Just one thing about the implementation:

> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  lib/devres.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/lib/devres.c b/lib/devres.c
> index fe0c63caeb68..27f280a39dca 100644
> --- a/lib/devres.c
> +++ b/lib/devres.c
> @@ -125,12 +125,13 @@ __devm_ioremap_resource(struct device *dev,
> const struct resource *res,
>         resource_size_t size;
>         void __iomem *dest_ptr;
>         char *pretty_name;
> +       int ret;
>  
>         BUG_ON(!dev);
>  
>         if (!res || resource_type(res) != IORESOURCE_MEM) {
> -               dev_err(dev, "invalid resource %pR\n", res);
> -               return IOMEM_ERR_PTR(-EINVAL);
> +               ret = dev_err_probe(dev, -EINVAL, "invalid resource
> %pR\n", res);
> +               return IOMEM_ERR_PTR(ret);

So as I see it -EINVAL is just piped through dev_err_probe() and is
never changed.
Don't you think it would be better to drop variable 'ret' and just do
return IOMEM_ERR_PTR(-EINVAL);
as before?

That way it would be obvious that the error code is never changed and
it will always return -EINVAL. Otherwise you have to look up the
function definition of dev_err_probe().

The same would apply below.

Regards,
P.

>         }
>  
>         if (type == DEVM_IOREMAP && res->flags &
> IORESOURCE_MEM_NONPOSTED)
> @@ -144,20 +145,20 @@ __devm_ioremap_resource(struct device *dev,
> const struct resource *res,
>         else
>                 pretty_name = devm_kstrdup(dev, dev_name(dev),
> GFP_KERNEL);
>         if (!pretty_name) {
> -               dev_err(dev, "can't generate pretty name for resource
> %pR\n", res);
> -               return IOMEM_ERR_PTR(-ENOMEM);
> +               ret = dev_err_probe(dev, -ENOMEM, "can't generate
> pretty name for resource %pR\n", res);
> +               return IOMEM_ERR_PTR(ret);
>         }
>  
>         if (!devm_request_mem_region(dev, res->start, size,
> pretty_name)) {
> -               dev_err(dev, "can't request region for resource
> %pR\n", res);
> -               return IOMEM_ERR_PTR(-EBUSY);
> +               ret = dev_err_probe(dev, -EBUSY, "can't request
> region for resource %pR\n", res);
> +               return IOMEM_ERR_PTR(ret);
>         }
>  
>         dest_ptr = __devm_ioremap(dev, res->start, size, type);
>         if (!dest_ptr) {
> -               dev_err(dev, "ioremap failed for resource %pR\n",
> res);
>                 devm_release_mem_region(dev, res->start, size);
> -               dest_ptr = IOMEM_ERR_PTR(-ENOMEM);
> +               ret = dev_err_probe(dev, -ENOMEM, "ioremap failed for
> resource %pR\n", res);
> +               return IOMEM_ERR_PTR(ret);
>         }
>  
>         return dest_ptr;