module: Optimize search_module_extables()

While looking through the __ex_table stuff I found that we do a linear
lookup of the module. Also fix up a comment.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Jessica Yu <jeyu@redhat.com>

1 files changed, 14 insertions, 13 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 330f64e7e193..32d0d32abbf6 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -4170,22 +4170,23 @@ const struct exception_table_entry *search_module_extables(unsigned long addr)
         struct module *mod;
 
         preempt_disable();
-        list_for_each_entry_rcu(mod, &modules, list) {
-                if (mod->state == MODULE_STATE_UNFORMED)
-                        continue;
-                if (mod->num_exentries == 0)
-                        continue;
+        mod = __module_address(addr);
+        if (!mod)
+                goto out;
 
-                e = search_extable(mod->extable,
-                                   mod->extable + mod->num_exentries - 1,
-                                   addr);
-                if (e)
-                        break;
-        }
+        if (!mod->num_exentries)
+                goto out;
+
+        e = search_extable(mod->extable,
+                           mod->extable + mod->num_exentries - 1,
+                           addr);
+out:
         preempt_enable();
 
-        /* Now, if we found one, we are running inside it now, hence
-           we cannot unload the module, hence no refcnt needed. */
+        /*
+         * Now, if we found one, we are running inside it now, hence
+         * we cannot unload the module, hence no refcnt needed.
+         */
         return e;
 }