module: better OOPS and lockdep coverage for loading modules

If we put the module in the linked list *before* calling into to, we
get the module name and functions in the OOPS (is_module_address can
find the module).  It also helps lockdep in a similar way.

Acked-and-tested-by: Joern Engel <joern@lazybastard.org>
Tested-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 20 insertions, 18 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 276abd7..12067ff 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1294,6 +1294,17 @@ static void mod_kobject_remove(struct module *mod)
 }
 
 /*
+ * link the module with the whole machine is stopped with interrupts off
+ * - this defends against kallsyms not taking locks
+ */
+static int __link_module(void *_mod)
+{
+	struct module *mod = _mod;
+	list_add(&mod->list, &modules);
+	return 0;
+}
+
+/*
  * unlink the module with the whole machine is stopped with interrupts off
  * - this defends against kallsyms not taking locks
  */
@@ -2035,6 +2046,11 @@ static struct module *load_module(void __user *umod,
 		printk(KERN_WARNING "%s: Ignoring obsolete parameters\n",
 		       mod->name);
 
+	/* Now sew it into the lists so we can get lockdep and oops
+         * info during argument parsing.  Noone should access us, since
+         * strong_try_module_get() will fail. */
+	stop_machine_run(__link_module, mod, NR_CPUS);
+
 	/* Size of section 0 is 0, so this works well if no params */
 	err = parse_args(mod->name, mod->args,
 			 (struct kernel_param *)
@@ -2043,7 +2059,7 @@ static struct module *load_module(void __user *umod,
 			 / sizeof(struct kernel_param),
 			 NULL);
 	if (err < 0)
-		goto arch_cleanup;
+		goto unlink;
 
 	err = mod_sysfs_setup(mod,
 			      (struct kernel_param *)
@@ -2051,7 +2067,7 @@ static struct module *load_module(void __user *umod,
 			      sechdrs[setupindex].sh_size
 			      / sizeof(struct kernel_param));
 	if (err < 0)
-		goto arch_cleanup;
+		goto unlink;
 	add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
 	add_notes_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
 
@@ -2066,7 +2082,8 @@ static struct module *load_module(void __user *umod,
 	/* Done! */
 	return mod;
 
- arch_cleanup:
+ unlink:
+	stop_machine_run(__unlink_module, mod, NR_CPUS);
 	module_arch_cleanup(mod);
  cleanup:
 	kobject_del(&mod->mkobj.kobj);
@@ -2091,17 +2108,6 @@ static struct module *load_module(void __user *umod,
 	goto free_hdr;
 }
 
-/*
- * link the module with the whole machine is stopped with interrupts off
- * - this defends against kallsyms not taking locks
- */
-static int __link_module(void *_mod)
-{
-	struct module *mod = _mod;
-	list_add(&mod->list, &modules);
-	return 0;
-}
-
 /* This is where the real work happens */
 asmlinkage long
 sys_init_module(void __user *umod,
@@ -2126,10 +2132,6 @@ sys_init_module(void __user *umod,
 		return PTR_ERR(mod);
 	}
 
-	/* Now sew it into the lists.  They won't access us, since
-           strong_try_module_get() will fail. */
-	stop_machine_run(__link_module, mod, NR_CPUS);
-
 	/* Drop lock so they can recurse */
 	mutex_unlock(&module_mutex);