From patchwork Wed Dec 7 13:53:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zheng Yejian X-Patchwork-Id: 13067160 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 E8DA1C4708E for ; Wed, 7 Dec 2022 13:52:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229586AbiLGNwo (ORCPT ); Wed, 7 Dec 2022 08:52:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229741AbiLGNwn (ORCPT ); Wed, 7 Dec 2022 08:52:43 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C705D6344; Wed, 7 Dec 2022 05:52:39 -0800 (PST) Received: from dggpeml100012.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4NRzBy0p85zqSqk; Wed, 7 Dec 2022 21:48:26 +0800 (CST) Received: from localhost.localdomain (10.67.175.61) by dggpeml100012.china.huawei.com (7.185.36.121) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 7 Dec 2022 21:52:36 +0800 From: Zheng Yejian To: , , CC: , , Subject: [PATCH] tracing/hist: Fix issue of losting command info in error_log Date: Wed, 7 Dec 2022 21:53:26 +0800 Message-ID: <20221207135326.3483216-1-zhengyejian1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.61] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml100012.china.huawei.com (7.185.36.121) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org When input some constructed invalid 'trigger' command, command info in 'error_log' are lost [1]. The root cause is that there is a path that event_hist_trigger_parse() is recursely called once and 'last_cmd' which save origin command is cleared, then later calling of hist_err() will no longer record origin command info: event_hist_trigger_parse() { last_cmd_set() // <1> 'last_cmd' save origin command here at first create_actions() { onmatch_create() { action_create() { trace_action_create() { trace_action_create_field_var() { create_field_var_hist() { event_hist_trigger_parse() { // <2> recursely called once hist_err_clear() // <3> 'last_cmd' is cleared here } hist_err() // <4> No longer find origin command!!! Since 'glob' is empty string while running into the recurse call, we can trickly check it and bypass the call of hist_err_clear() to solve it. [1] # cd /sys/kernel/tracing # echo "my_synth_event int v1; int v2; int v3;" >> synthetic_events # echo 'hist:keys=pid' >> events/sched/sched_waking/trigger # echo "hist:keys=next_pid:onmatch(sched.sched_waking).my_synth_event(\ pid,pid1)" >> events/sched/sched_switch/trigger # cat error_log [ 8.405018] hist:sched:sched_switch: error: Couldn't find synthetic event Command: hist:keys=next_pid:onmatch(sched.sched_waking).my_synth_event(pid,pid1) ^ [ 8.816902] hist:sched:sched_switch: error: Couldn't find field Command: hist:keys=next_pid:onmatch(sched.sched_waking).my_synth_event(pid,pid1) ^ [ 8.816902] hist:sched:sched_switch: error: Couldn't parse field variable Command: hist:keys=next_pid:onmatch(sched.sched_waking).my_synth_event(pid,pid1) ^ [ 8.999880] : error: Couldn't find field Command: ^ [ 8.999880] : error: Couldn't parse field variable Command: ^ [ 8.999880] : error: Couldn't find field Command: ^ [ 8.999880] : error: Couldn't create histogram for field Command: ^ Fixes: f404da6e1d46 ("tracing: Add 'last error' error facility for hist triggers") Signed-off-by: Zheng Yejian --- kernel/trace/trace_events_hist.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 1c82478e8dff..b6e5724a9ea3 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -6438,7 +6438,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, if (se) se->ref++; out: - if (ret == 0) + if (ret == 0 && glob[0]) hist_err_clear(); return ret;