Re: [PATCH] software node: replace -EEXIST with -EBUSY

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Sat, Dec 20, 2025 at 04:55:00AM +0100, Daniel Gomez wrote:
> From: Daniel Gomez <da.gomez@samsung.com>
> 
> The -EEXIST error code is reserved by the module loading infrastructure
> to indicate that a module is already loaded. When a module's init
> function returns -EEXIST, userspace tools like kmod interpret this as
> "module already loaded" and treat the operation as successful, returning
> 0 to the user even though the module initialization actually failed.
> 
> This follows the precedent set by commit 54416fd76770 ("netfilter:
> conntrack: helper: Replace -EEXIST by -EBUSY") which fixed the same
> issue in nf_conntrack_helper_register().
> 
> Affected modules:
>   * meraki_mx100 pcengines_apuv2

As I read the description the problem is in the kmod/do_module_init(). If you
need a clear way to distinguish that, use some unique error code in the kernel
module loader. I fully agree with Greg that this is a slippery slope which
leads to -EEXIST to be forbidden in the drivers which is no go.

NAK.

-- 
With Best Regards,
Andy Shevchenko