From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36CD7C33CB6 for ; Thu, 16 Jan 2020 14:46:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0DB382075B for ; Thu, 16 Jan 2020 14:46:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579185985; bh=VutGjxWwdtEPcCBYrGyCDjwJ75btz6UR1pL3UbFs08c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=srgkrLoGlMfk87BEiEKdJKe9evqzxFpF/OxD7QXBuC/Vh4eZzhM04eS1JnoGFzWMa 3+9ST06fY6+QditNNhlbu/H5tNjj/Qwsye769aejvkvD8QRL61lbWZYjMLVMRIHmqb xC0AQh77t8KMY+HODegW++ZLtA5HzeEJZvuKL+FY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726410AbgAPOqY (ORCPT ); Thu, 16 Jan 2020 09:46:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:36976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726362AbgAPOqY (ORCPT ); Thu, 16 Jan 2020 09:46:24 -0500 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1F47820684; Thu, 16 Jan 2020 14:46:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579185982; bh=VutGjxWwdtEPcCBYrGyCDjwJ75btz6UR1pL3UbFs08c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qCopYxEeBllyD83t5ggx9lLCMEqXOioXxFbSCQYI7g2LtcvQJ+qALffU9m3YOzIU3 9iV9mxRqVVBkBKJ3PY2MpI/Q1qpOXdsfillIc1IfIksCIQfudpXlGrnArkVNTJ0ceG RLw8DQq7KHGJV/3hnu7IvzrmRfI+Vw7Wqo6YhXBs= From: Masami Hiramatsu To: Brendan Gregg , Steven Rostedt , Alexei Starovoitov Cc: mhiramat@kernel.org, Ingo Molnar , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Borkmann , Arnaldo Carvalho de Melo , "David S . Miller" , paulmck@kernel.org, joel@joelfernandes.org, "Naveen N . Rao" , Anil S Keshavamurthy Subject: [RFT PATCH 12/13] tracing/kprobe: Free probe event asynchronously Date: Thu, 16 Jan 2020 23:46:17 +0900 Message-Id: <157918597739.29301.3329193112465223174.stgit@devnote2> X-Mailer: git-send-email 2.20.1 In-Reply-To: <157918584866.29301.6941815715391411338.stgit@devnote2> References: <157918584866.29301.6941815715391411338.stgit@devnote2> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Free each probe event data structure asynchronously when deleting probe events. But this finally synchronizes RCU so that we make sure all event handlers have finished. Signed-off-by: Masami Hiramatsu --- kernel/trace/trace_dynevent.c | 5 ++++ kernel/trace/trace_kprobe.c | 46 +++++++++++++++++++++++++++++++++++------ 2 files changed, 44 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c index 89779eb84a07..2d5e8d457309 100644 --- a/kernel/trace/trace_dynevent.c +++ b/kernel/trace/trace_dynevent.c @@ -70,6 +70,9 @@ int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type) if (ret) break; } + + /* Wait for running events because of async event unregistration */ + synchronize_rcu(); mutex_unlock(&event_mutex); return ret; @@ -164,6 +167,8 @@ int dyn_events_release_all(struct dyn_event_operations *type) if (ret) break; } + /* Wait for running events because of async event unregistration */ + synchronize_rcu(); out: mutex_unlock(&event_mutex); diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 906af1ffe2b2..f7e0370b10ae 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -551,7 +551,35 @@ static void __unregister_trace_kprobe(struct trace_kprobe *tk) } } -/* Unregister a trace_probe and probe_event */ +static void free_trace_kprobe_cb(struct rcu_head *head) +{ + struct kprobe *kp = container_of(head, struct kprobe, rcu); + struct kretprobe *rp = container_of(kp, struct kretprobe, kp); + struct trace_kprobe *tk = container_of(rp, struct trace_kprobe, rp); + + if (trace_kprobe_is_return(tk)) + kretprobe_free_callback(head); + else + kprobe_free_callback(head); + free_trace_kprobe(tk); +} + +static void __unregister_trace_kprobe_async(struct trace_kprobe *tk) +{ + if (trace_kprobe_is_registered(tk)) { + if (trace_kprobe_is_return(tk)) + unregister_kretprobe_async(&tk->rp, + free_trace_kprobe_cb); + else + unregister_kprobe_async(&tk->rp.kp, + free_trace_kprobe_cb); + } +} + +/* + * Unregister a trace_probe and probe_event asynchronously. + * Caller must wait for RCU. + */ static int unregister_trace_kprobe(struct trace_kprobe *tk) { /* If other probes are on the event, just unregister kprobe */ @@ -570,9 +598,17 @@ static int unregister_trace_kprobe(struct trace_kprobe *tk) return -EBUSY; unreg: - __unregister_trace_kprobe(tk); dyn_event_remove(&tk->devent); + /* + * This trace_probe_unlink() can free the trace_event_call linked to + * this probe. + * We can do this before unregistering because this probe is + * already disabled and the disabling process waits enough period + * for all handlers finished. IOW, the disabling process must wait + * RCU sync at least once before returning to its caller. + */ trace_probe_unlink(&tk->tp); + __unregister_trace_kprobe_async(tk); return 0; } @@ -928,11 +964,7 @@ static int create_or_delete_trace_kprobe(int argc, char **argv) static int trace_kprobe_release(struct dyn_event *ev) { struct trace_kprobe *tk = to_trace_kprobe(ev); - int ret = unregister_trace_kprobe(tk); - - if (!ret) - free_trace_kprobe(tk); - return ret; + return unregister_trace_kprobe(tk); } static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)