From nobody Sun Feb 8 18:15:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BE30EB64D9 for ; Thu, 15 Jun 2023 13:36:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344408AbjFONgY (ORCPT ); Thu, 15 Jun 2023 09:36:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344734AbjFONfY (ORCPT ); Thu, 15 Jun 2023 09:35:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B44A3AB8 for ; Thu, 15 Jun 2023 06:34:46 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B8DCF639D3 for ; Thu, 15 Jun 2023 13:34:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 94D82C43391; Thu, 15 Jun 2023 13:34:17 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1q9n7A-000Tpl-2A; Thu, 15 Jun 2023 09:34:16 -0400 Message-ID: <20230615133416.491731786@goodmis.org> User-Agent: quilt/0.66 Date: Thu, 15 Jun 2023 09:05:40 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Christian Brauner , Beau Belgrave Subject: [for-linus][PATCH 09/15] tracing/user_events: Remove user_ns walk for groups References: <20230615130531.200384328@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Beau Belgrave During discussions it was suggested that user_ns is not a good place to try to attach a tracing namespace. The current code has stubs to enable that work that are very likely to change and incur a performance cost. Remove the user_ns walk when creating a group and determining the system name to use, since it's unlikely user_ns will be used in the future. Link: https://lore.kernel.org/all/20230601-urenkel-holzofen-cd9403b9cadd@br= auner/ Link: https://lore.kernel.org/linux-trace-kernel/20230601224928.301-1-beaub= @linux.microsoft.com Suggested-by: Christian Brauner Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_user.c | 42 ++++---------------------------- 1 file changed, 5 insertions(+), 37 deletions(-) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_u= ser.c index 49914b6cb651..cf6d4c02c363 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -182,21 +182,11 @@ static void user_event_group_destroy(struct user_even= t_group *group) kfree(group); } =20 -static char *user_event_group_system_name(struct user_namespace *user_ns) +static char *user_event_group_system_name(void) { char *system_name; int len =3D sizeof(USER_EVENTS_SYSTEM) + 1; =20 - if (user_ns !=3D &init_user_ns) { - /* - * Unexpected at this point: - * We only currently support init_user_ns. - * When we enable more, this will trigger a failure so log. - */ - pr_warn("user_events: Namespace other than init_user_ns!\n"); - return NULL; - } - system_name =3D kmalloc(len, GFP_KERNEL); =20 if (!system_name) @@ -207,34 +197,12 @@ static char *user_event_group_system_name(struct user= _namespace *user_ns) return system_name; } =20 -static inline struct user_event_group -*user_event_group_from_user_ns(struct user_namespace *user_ns) -{ - if (user_ns =3D=3D &init_user_ns) - return init_group; - - return NULL; -} - static struct user_event_group *current_user_event_group(void) { - struct user_namespace *user_ns =3D current_user_ns(); - struct user_event_group *group =3D NULL; - - while (user_ns) { - group =3D user_event_group_from_user_ns(user_ns); - - if (group) - break; - - user_ns =3D user_ns->parent; - } - - return group; + return init_group; } =20 -static struct user_event_group -*user_event_group_create(struct user_namespace *user_ns) +static struct user_event_group *user_event_group_create(void) { struct user_event_group *group; =20 @@ -243,7 +211,7 @@ static struct user_event_group if (!group) return NULL; =20 - group->system_name =3D user_event_group_system_name(user_ns); + group->system_name =3D user_event_group_system_name(); =20 if (!group->system_name) goto error; @@ -2603,7 +2571,7 @@ static int __init trace_events_user_init(void) if (!fault_cache) return -ENOMEM; =20 - init_group =3D user_event_group_create(&init_user_ns); + init_group =3D user_event_group_create(); =20 if (!init_group) { kmem_cache_destroy(fault_cache); --=20 2.39.2