Module: check to see if we have a built in module with the same name

When trying to load a module with the same name as a built-in one, a
scary kobject backtrace comes up.  Prevent that from checking for this
condition and warning the user as to what exactly is going on.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/module.c b/kernel/module.c
index af3f81a94745..f6a4e721fd49 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1230,6 +1230,7 @@ void module_remove_modinfo_attrs(struct module *mod)
 int mod_sysfs_init(struct module *mod)
 {
         int err;
+        struct kobject *kobj;
 
         if (!module_sysfs_initialized) {
                 printk(KERN_ERR "%s: module sysfs not initialized\n",
@@ -1237,6 +1238,15 @@ int mod_sysfs_init(struct module *mod)
                 err = -EINVAL;
                 goto out;
         }
+
+        kobj = kset_find_obj(module_kset, mod->name);
+        if (kobj) {
+                printk(KERN_ERR "%s: module is already loaded\n", mod->name);
+                kobject_put(kobj);
+                err = -EINVAL;
+                goto out;
+        }
+
         mod->mkobj.mod = mod;
 
         memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj));