[RFC 11/12] module: use list_add_tail_rcu() when adding module

From: Luis Chamberlain <mcgrof@kernel.org>
To: linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org,
	pmladek@suse.com, david@redhat.com, petr.pavlu@suse.com,
	prarit@redhat.com
Cc: christophe.leroy@csgroup.eu, song@kernel.org, mcgrof@kernel.org,
	torvalds@linux-foundation.org
Subject: [RFC 11/12] module: use list_add_tail_rcu() when adding module
Date: Fri, 10 Mar 2023 21:17:11 -0800	[thread overview]
Message-ID: <20230311051712.4095040-12-mcgrof@kernel.org> (raw)
In-Reply-To: <20230311051712.4095040-1-mcgrof@kernel.org>

Put a new module at the end of the list intead of making
new modules at the top of the list. find_module_all() start
the hunt using the first entry on the list, if we assume
that the modules which are first loaded are the most
frequently looked for modules this should provide a tiny
optimization.

This is theoretical, and could use more actual data by analzying
the impact of this patch on boot time a slew of systems using
systemd-analyze.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 kernel/module/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 909454f9616e..bc9202b60d55 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2608,7 +2608,7 @@ static int add_unformed_module(struct module *mod)
 		goto out;
 
 	mod_update_bounds(mod);
-	list_add_rcu(&mod->list, &modules);
+	list_add_tail_rcu(&mod->list, &modules);
 	mod_tree_insert(mod);
 	err = 0;
 
-- 
2.39.1

