From: 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. Add a
comment to clarify what this means for module authors and maintainers
to ensure the module_init() path return error do not conflict with the
reserved one.

Signed-off-by: Daniel Gomez <[email protected]>
---
 kernel/module/main.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index a8394d81174f..655a780981d3 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3038,6 +3038,14 @@ static noinline int do_init_module(struct module *mod)
        if (mod->init != NULL)
                ret = do_one_initcall(mod->init);
        if (ret < 0) {
+               /*
+                * -EEXIST is reserved by the module loader to mean "already 
loaded". kmod
+                * interprets this as success, hiding real module failures. 
Override with
+                * -EBUSY and warn.
+                *
+                * Module authors: use -EBUSY or -EALREADY instead of -EEXIST.
+                * See Documentation/kernel-hacking/hacking.rst
+                */
                if (ret == -EEXIST) {
                        pr_warn("%s: init suspiciously returned -EEXIST: 
Overriding with -EBUSY\n",
                                mod->name);

-- 
2.52.0


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