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=-17.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 D80D4C433DB for ; Fri, 29 Jan 2021 05:50:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6F8364E02 for ; Fri, 29 Jan 2021 05:50:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231967AbhA2FuI (ORCPT ); Fri, 29 Jan 2021 00:50:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230249AbhA2Ft5 (ORCPT ); Fri, 29 Jan 2021 00:49:57 -0500 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AED51C061756 for ; Thu, 28 Jan 2021 21:49:17 -0800 (PST) Received: by mail-pf1-x432.google.com with SMTP id w14so5550609pfi.2 for ; Thu, 28 Jan 2021 21:49:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=KHa7MkSd62NVn3SBTV2HKSS7Xv4AilcAIIMBnC9C0u8=; b=coNJ+a8UaKDyVWKzGENVJ2m/ljgVgd5TVMGPhNcCGExGIZgIMixdPcA+sRvrmug8Ju V0uyDh6CW4uRZkf5jE9t2/x/lc4GRDuaZfMniR/gTBi3qdK6Irvp2nug+Q0DiVPF0GNc 3H2gY0kJLI+b+l6V0TnbABNMu5Ii9MbHVzWeiHnTTmDns0HjL89ymy1Ey1GEkgvZk4LQ o/RQza4bM4itHUOHpLKYPjTVUBYqR6rgcRQRfQxHOyIDGZ1zx6fD7jNNsM0BHX43fBbu a4S0cmmbvHOKGHuLaCykVNCGfHfC6tqUK9MdPHAusGjuAblvab2J+pV+fYkPQDSLYZx6 MaHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=KHa7MkSd62NVn3SBTV2HKSS7Xv4AilcAIIMBnC9C0u8=; b=JYCogME5N2E5fL+VwxJS2ohX85hv5K/qFYILo4yn0fsMbBOjrutyt+O6ttSluD5hiD 4UygMZ0QIjDqVDFztfjSMWvagGHiTxBXMNxmdOy6KxjyX1CQPFn+PQ1TWmEXyAwEGulu DDIEAA6kYf/ylmcUlkeTVd1mUlotdEfPb3dOOumpaGtquwaHJZPw3gl3OSCP3KDQsNBV pflIIeqjk15UVckIEnbSpqrvfAwKSF8gu9RgC/KJxkPwNY4IJIZNV3sSLQ+wFr5Li2kT X3Hz7SPYN/PijlkhZX4n699+Fm/0wgdGssOqosiXRB3Vba+jRFjqI0900ePAV7hg6VXL R2Qw== X-Gm-Message-State: AOAM531vtTHkkpXimniMJsImn14kYt+lF2UgGmnA/v5inyFbuS0E5eXr 7rzcM38L8qUwIVtiqLN+w+g= X-Google-Smtp-Source: ABdhPJxPjjkbwI422S8H6wZXfuKtfXMa3o4QczyIfzAGYLBxJVTRXk4hQEuzMVX1w011cIz0credgg== X-Received: by 2002:a63:4851:: with SMTP id x17mr3008682pgk.451.1611899357304; Thu, 28 Jan 2021 21:49:17 -0800 (PST) Received: from balhae.roam.corp.google.com ([114.129.115.223]) by smtp.gmail.com with ESMTPSA id j13sm7408098pfr.214.2021.01.28.21.49.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Jan 2021 21:49:16 -0800 (PST) Sender: Namhyung Kim From: Namhyung Kim To: Arnaldo Carvalho de Melo , Jiri Olsa Cc: Ingo Molnar , Peter Zijlstra , Mark Rutland , Alexander Shishkin , LKML , Stephane Eranian , Andi Kleen , Ian Rogers Subject: [PATCH 3/3] perf tools: Use scandir() to iterate threads Date: Fri, 29 Jan 2021 14:49:01 +0900 Message-Id: <20210129054901.1705483-4-namhyung@kernel.org> X-Mailer: git-send-email 2.30.0.365.g02bc693789-goog In-Reply-To: <20210129054901.1705483-1-namhyung@kernel.org> References: <20210129054901.1705483-1-namhyung@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Like in __event__synthesize_thread(), I think it's better to use scandir() instead of the readdir() loop. In case some malicious task continues to create new threads, the readdir() loop will run over and over to collect tids. The scandir() also has the problem but the window is much smaller since it doesn't do much work during the iteration. Also add filter_task() function as we only care the tasks. Signed-off-by: Namhyung Kim --- tools/perf/util/synthetic-events.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 8b38228c83d8..334e577b8ae4 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -709,6 +709,11 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t return rc; } +static int filter_task(const struct dirent *dirent) +{ + return isdigit(dirent->d_name[0]); +} + static int __event__synthesize_thread(union perf_event *comm_event, union perf_event *mmap_event, union perf_event *fork_event, @@ -717,10 +722,10 @@ static int __event__synthesize_thread(union perf_event *comm_event, struct perf_tool *tool, struct machine *machine, bool mmap_data) { char filename[PATH_MAX]; - DIR *tasks; - struct dirent *dirent; + struct dirent **dirent; pid_t tgid, ppid; int rc = 0; + int i, n; /* special case: only send one comm event using passed in pid */ if (!full) { @@ -752,18 +757,16 @@ static int __event__synthesize_thread(union perf_event *comm_event, snprintf(filename, sizeof(filename), "%s/proc/%d/task", machine->root_dir, pid); - tasks = opendir(filename); - if (tasks == NULL) { - pr_debug("couldn't open %s\n", filename); - return 0; - } + n = scandir(filename, &dirent, filter_task, alphasort); + if (n < 0) + return n; - while ((dirent = readdir(tasks)) != NULL) { + for (i = 0; i < n; i++) { char *end; pid_t _pid; bool kernel_thread; - _pid = strtol(dirent->d_name, &end, 10); + _pid = strtol(dirent[i]->d_name, &end, 10); if (*end) continue; @@ -796,7 +799,10 @@ static int __event__synthesize_thread(union perf_event *comm_event, } } - closedir(tasks); + for (i = 0; i < n; i++) + zfree(&dirent[i]); + free(dirent); + return rc; } @@ -981,7 +987,7 @@ int perf_event__synthesize_threads(struct perf_tool *tool, return 0; snprintf(proc_path, sizeof(proc_path), "%s/proc", machine->root_dir); - n = scandir(proc_path, &dirent, 0, alphasort); + n = scandir(proc_path, &dirent, filter_task, alphasort); if (n < 0) return err; -- 2.30.0.365.g02bc693789-goog