linux-kernel - Re: [PATCH] [v3] module: don't ignore sysfs_create

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Date: Tue, 26 Mar 2024 17:29:12 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>, Luis Chamberlain <mcgrof@...nel.org>,
	linux-modules@...r.kernel.org,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Jens Axboe <axboe@...nel.dk>,
	"Ricardo B. Marliere" <ricardo@...liere.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v3] module: don't ignore sysfs_create_link() failures

On Tue, Mar 26, 2024 at 03:57:18PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> The sysfs_create_link() return code is marked as __must_check, but the
> module_add_driver() function tries hard to not care, by assigning the
> return code to a variable. When building with 'make W=1', gcc still
> warns because this variable is only assigned but not used:
> 
> drivers/base/module.c: In function 'module_add_driver':
> drivers/base/module.c:36:6: warning: variable 'no_warn' set but not used [-Wunused-but-set-variable]
> 
> Rework the code to properly unwind and return the error code to the
> caller. My reading of the original code was that it tries to
> not fail when the links already exist, so keep ignoring -EEXIST
> errors.

> Cc: Luis Chamberlain <mcgrof@...nel.org>
> Cc: linux-modules@...r.kernel.org
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>

Wondering if you can move these to be after --- to avoid polluting commit
message. This will have the same effect and be archived on lore. But on
pros side it will unload the commit message(s) from unneeded noise.

..

> +	error = module_add_driver(drv->owner, drv);
> +	if (error) {
> +		printk(KERN_ERR "%s: failed to create module links for %s\n",
> +			__func__, drv->name);

What's wrong with pr_err()? Even if it's not a style used, in a new pieces of
code this can be improved beforehand. So, we will reduce a technical debt, and
not adding to it.

> +		goto out_detach;
> +	}

..

> +int module_add_driver(struct module *mod, struct device_driver *drv)
>  {
>  	char *driver_name;
> -	int no_warn;
> +	int ret;

I would move it...

>  	struct module_kobject *mk = NULL;

..to be here.

-- 
With Best Regards,
Andy Shevchenko