Hi Daniel, Thanks for the patch.
On Sat, Dec 20, 2025 at 04:55:00AM +0100, Daniel Gomez wrote: > From: Daniel Gomez <[email protected]> > > 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 > > Signed-off-by: Daniel Gomez <[email protected]> > --- > The error code -EEXIST is reserved by the kernel module loader to > indicate that a module with the same name is already loaded. When a > module's init function returns -EEXIST, kmod interprets this as "module > already loaded" and reports success instead of failure [1]. > > The kernel module loader will include a safety net that provides -EEXIST > to -EBUSY with a warning [2], and a documentation patch has been sent to > prevent future occurrences [3]. > > These affected code paths were identified using a static analysis tool > [4] that traces -EEXIST returns to module_init(). The tool was developed > with AI assistance and all findings were manually validated. This might not be the only case where -EEXIST may be returned by loading a module. The patch is fine IMO but I'd just change -EEXIST to -EBUSY in e.g. do_init_module() to avoid this being an actual bug elsewhere. I wonder what others think. > > Link: https://lore.kernel.org/all/[email protected]/ [1] > Link: > https://lore.kernel.org/all/[email protected]/ > [2] > Link: > https://lore.kernel.org/all/20251218-dev-module-init-eexists-modules-docs-v1-0-361569aa7...@samsung.com/ > [3] > Link: https://gitlab.com/-/snippets/4913469 [4] > --- > drivers/base/swnode.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c > index 16a8301c25d6..083593d99a18 100644 > --- a/drivers/base/swnode.c > +++ b/drivers/base/swnode.c > @@ -919,7 +919,7 @@ int software_node_register(const struct software_node > *node) > struct swnode *parent = software_node_to_swnode(node->parent); > > if (software_node_to_swnode(node)) > - return -EEXIST; > + return -EBUSY; > > if (node->parent && !parent) > return -EINVAL; > -- Regards, Sakari Ailus
