Re: [PATCH] [v3] module: don't ignore sysfs_create_link() failures
On Tue, Mar 26, 2024, at 16:29, Andy Shevchenko wrote:
> On Tue, Mar 26, 2024 at 03:57:18PM +0100, Arnd Bergmann wrote:
>> From: Arnd Bergmann
>>
>> 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
>> Cc: linux-modu...@vger.kernel.org
>> Cc: Greg Kroah-Hartman
>> Cc: "Rafael J. Wysocki"
>
> 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.
Done
>
>> +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.
I think that would be more confusing, and would rather keep the
style consistent. There is no practical difference here.
>> +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.
Done
Arnd
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
>
> 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
> Cc: linux-modu...@vger.kernel.org
> Cc: Greg Kroah-Hartman
> Cc: "Rafael J. Wysocki"
> Fixes: e17e0f51aeea ("Driver core: show drivers in /sys/module/")
> See-also: 4a7fb6363f2d ("add __must_check to device management code")
> Signed-off-by: Arnd Bergmann
> ---
> v3: make error handling stricter, add unwinding,
> fix build fail with CONFIG_MODULES=n
> v2: rework to actually handle the error. I have not tested the
> error handling beyond build testing, so please review carefully.
> ---
> drivers/base/base.h | 9 ++---
> drivers/base/bus.c| 9 -
> drivers/base/module.c | 42 +++---
> 3 files changed, 45 insertions(+), 15 deletions(-)
Reviewed-by: Greg Kroah-Hartman
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
>
> 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
> Cc: linux-modu...@vger.kernel.org
> Cc: Greg Kroah-Hartman
> Cc: "Rafael J. Wysocki"
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
