From patchwork Tue May 30 23:52:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 13261229 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 309E6C7EE23 for ; Tue, 30 May 2023 23:53:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233869AbjE3XxQ (ORCPT ); Tue, 30 May 2023 19:53:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37014 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231960AbjE3XxP (ORCPT ); Tue, 30 May 2023 19:53:15 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5BF86AA; Tue, 30 May 2023 16:53:12 -0700 (PDT) Received: from W11-BEAU-MD.localdomain (unknown [76.135.27.212]) by linux.microsoft.com (Postfix) with ESMTPSA id 931B920FC46B; Tue, 30 May 2023 16:53:11 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 931B920FC46B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1685490791; bh=Z9owk60mLsQ9CmOnrrn5zp1mIr1kGtuAxKwMw6iuEA8=; h=From:To:Cc:Subject:Date:From; b=bmV7NDmUKut9lVN6Gvy8cX/SOgoVrBGj33TsV9lFkCIZuKLAmFtwIhhaIuGxP/E6T 80lX/RosXgdoXKkJfrikQ1vp6iGSAqt5s/Tmtot07RlOwgTJPi4vxOm6YvSnCh3Rzn ZkzBpfeARZOkmtoZoBBmTMPVRdM9R/tnion8VfjU= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ast@kernel.org, dcook@linux.microsoft.com Subject: [PATCH 0/5] tracing/user_events: Add auto-del flag for events Date: Tue, 30 May 2023 16:52:59 -0700 Message-Id: <20230530235304.2726-1-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org As part of the discussions for user_events aligning to be used with eBPF it became clear [1] we needed a way to delete events without having to rely upon the delete IOCTL. Steven suggested that we simply have an owner for the event, however, the event can be held by more than just the first register FD, such as perf/ftrace or additional registers. In order to handle all those cases, we must only delete after all references are gone from both user and kernel space. This series adds a new register flag, USER_EVENT_REG_AUTO_DEL, which causes the event to delete itself upon the last put reference. We cannot fully drop the delete IOCTL, since we still want to enable events to be registered early via dynamic_events and persist. If the auto delete flag was used during dynamic_events, the event would delete immediately. We have a few key events that we enable immediately after boot and are monitored in our environments. Today this is done via dynamic events, however, it could also be done directly via the ABI by not passing the auto delete flag. NOTE: I'll need to merge this work once we take these [2] [3] patches into for-next. I'm happy to do so once they land there. 1: https://lore.kernel.org/linux-trace-kernel/20230518093600.3f119d68@rorschach.local.home/ 2: https://lore.kernel.org/linux-trace-kernel/20230529032100.286534-1-sunliming@kylinos.cn/ 3: https://lore.kernel.org/linux-trace-kernel/20230519230741.669-1-beaub@linux.microsoft.com/ Beau Belgrave (5): tracing/user_events: Store register flags on events tracing/user_events: Track refcount consistently via put/get tracing/user_events: Add flag to auto-delete events tracing/user_events: Add self-test for auto-del flag tracing/user_events: Add auto-del flag documentation Documentation/trace/user_events.rst | 21 +- include/uapi/linux/user_events.h | 10 +- kernel/trace/trace_events_user.c | 183 ++++++++++++++---- .../testing/selftests/user_events/abi_test.c | 115 ++++++++++- 4 files changed, 278 insertions(+), 51 deletions(-) base-commit: 3862f86c1529fa0016de6344eb974877b4cd3838