From patchwork Tue Jan 12 09:20:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tzvetomir Stoyanov (VMware)" X-Patchwork-Id: 12012857 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 C0D62C433DB for ; Tue, 12 Jan 2021 09:21:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7871122E01 for ; Tue, 12 Jan 2021 09:21:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390589AbhALJVX (ORCPT ); Tue, 12 Jan 2021 04:21:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732377AbhALJVW (ORCPT ); Tue, 12 Jan 2021 04:21:22 -0500 Received: from mail-ej1-x631.google.com (mail-ej1-x631.google.com [IPv6:2a00:1450:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7338C0617A2 for ; Tue, 12 Jan 2021 01:20:32 -0800 (PST) Received: by mail-ej1-x631.google.com with SMTP id g12so308334ejf.8 for ; Tue, 12 Jan 2021 01:20:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YC8+W9IviYLVe4KAzoDQWXwIO0NEa4o48S06NExlU0g=; b=Rc6RGmYCweqw6kOSejajW3mYTGLj7EFbxafvhWaGQLtABV7V5nTIw+oJzVM7shd/Nv E70GQ1zP97N56dkCgKUIqGlWGbf8vpM5UE6WcFkFX4orIFN7pJbblM9juFPcUWXtYHHO ruKQe7twfvYxKjW13EwOoPMCjmxP3PDRtngvmpCWQyYXBof5aIlU024nFc7EFiFwiHy1 bnbVBHBm8/w8iqZEbGKuRg1czE4xgK4sdbpxIoqQrzxjOdP5PHPtMxM4ozARc4ZPE1Ux VArrCW0djNBJMa9ETKzNguQ733Y41gQZ9tmi5FgeLLv9T65zQ7VvXj0hlLVDqLeWHAW7 S6hg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=YC8+W9IviYLVe4KAzoDQWXwIO0NEa4o48S06NExlU0g=; b=E3Fy+Wt4Kh47vNLZo4sWf+P3lDO3E8wVJgIwmMvYBzElX3W1rhB+d/rGsJ4IxDHwmP NO5/KGuKCstmz9dqP77uEydGfH+1N45LJ5OGpCw3seL9X8GE2UTuXDyusV2TTU19Zmor yrZwFNuDwzEOQNfkajfDFw+qsNjWn/zljhtxmLWI/yRy6IAPpv7LNwPbTdwlYHj7mV+g D3wVFCrwu5MI/g/p6WLlNtVmftTPB/wlnOcIQVRhfVagS41T9xNxYfX3YL2coD4my6Bf ftnwQFEBRnKv8c4w9xEub33lQo5kKck05Iec78BwPupFcmNcX/OAIeFOrNRfzSksMhEe wY2A== X-Gm-Message-State: AOAM531fvnHSb58hEpp1aFnyFJoxTVoKJOIixJPVS/RckYX95eUsxHF8 jxij6iQPZYsSlnFhhCnlR0BYEQl5z0zr636S X-Google-Smtp-Source: ABdhPJwuo6qTRkVL1L+lHy88SmuBYbclvw0epX/MGRArF/24toq5+qY0wT8MsU6tT88oTXvfeTtrzg== X-Received: by 2002:a17:906:87c3:: with SMTP id zb3mr1352942ejb.244.1610443231539; Tue, 12 Jan 2021 01:20:31 -0800 (PST) Received: from oberon.zico.biz ([83.222.187.186]) by smtp.gmail.com with ESMTPSA id rl7sm929187ejb.107.2021.01.12.01.20.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Jan 2021 01:20:30 -0800 (PST) From: "Tzvetomir Stoyanov (VMware)" To: rostedt@goodmis.org Cc: linux-trace-devel@vger.kernel.org Subject: [PATCH v2 4/7] libtracefs: Documentation for the new APIs for opening and reading ftrace files Date: Tue, 12 Jan 2021 11:20:21 +0200 Message-Id: <20210112092024.605705-5-tz.stoyanov@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210112092024.605705-1-tz.stoyanov@gmail.com> References: <20210112092024.605705-1-tz.stoyanov@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Man pages updated with documentation about: tracefs_instance_file_open(); tracefs_instance_file_read_number(); Signed-off-by: Tzvetomir Stoyanov (VMware) --- Documentation/libtracefs-instances-files.txt | 45 ++++++++++++++++++-- Documentation/libtracefs.txt | 2 + 2 files changed, 44 insertions(+), 3 deletions(-) diff --git a/Documentation/libtracefs-instances-files.txt b/Documentation/libtracefs-instances-files.txt index a9af1f7..124ef52 100644 --- a/Documentation/libtracefs-instances-files.txt +++ b/Documentation/libtracefs-instances-files.txt @@ -4,8 +4,8 @@ libtracefs(3) NAME ---- tracefs_file_exists, tracefs_dir_exists, tracefs_instance_get_file, -tracefs_instance_get_dir, tracefs_instance_file_write, -tracefs_instance_file_read - Work with files in tracing instances. +tracefs_instance_get_dir, tracefs_instance_file_open, tracefs_instance_file_write, +tracefs_instance_file_read, tracefs_instance_file_read_number - Work with files in tracing instances. SYNOPSIS -------- @@ -17,8 +17,10 @@ bool *tracefs_file_exists*(struct tracefs_instance pass:[*]_instance_, char pass bool *tracefs_dir_exists*(struct tracefs_instance pass:[*]_instance_, char pass:[*]_name_); char pass:[*]*tracefs_instance_get_file*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_); char pass:[*]*tracefs_instance_get_dir*(struct tracefs_instance pass:[*]_instance_); +int *tracefs_instance_file_open*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int _mode_); int *tracefs_instance_file_write*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, const char pass:[*]_str_); char pass:[*]*tracefs_instance_file_read*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int pass:[*]_psize_); +int *tracefs_instance_file_read_number*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, long long int pass:[*]_res_); -- @@ -41,12 +43,19 @@ The _tracefs_instance_get_dir()_ function returns the full path of the director with given _name_ in _instance_. Note, it does not check if the directory exists in the instance. +The _tracefs_instance_file_open()_ function opens trace _file_ from given _instance_ and returns +a file descriptor to it. The file access _mode_ can be specified, see *open*(3) for more details. +If -1 is passed as _mode_, default O_RDWR is used. + The _tracefs_instance_file_write()_ function writes a string _str_ in a _file_ from the given _instance_, without the terminating NULL character. -The _tracefs_instance_file_read()_ function reads the content of a _file_ from +The _tracefs_instance_file_read()_ function reads the content of a _file_ from the given _instance_. +The _tracefs_instance_file_read_number()_ function reads the content of a _file_ from +the given _instance_ and converts it to a long long integer, which is stored in _res_. + RETURN VALUE ------------ The _tracefs_file_exists()_ and _tracefs_dir_exists()_ functions return true if the @@ -56,6 +65,9 @@ The _tracefs_instance_get_file()_ and _tracefs_instance_get_dir()_ functions ret a string or NULL in case of an error. The returned string must be freed with _tracefs_put_tracing_file()_. +The _tracefs_instance_file_open()_ function returns a file descriptor to the opened file. It must be +closed with *close*(3). In case of an error, -1 is returned. + The _tracefs_instance_file_write()_ function returns the number of written bytes, or -1 in case of an error. @@ -63,6 +75,9 @@ The _tracefs_instance_file_read()_ function returns a pointer to a NULL terminat string, read from the file, or NULL in case of an error. The returned string must be freed with free(). +The _tracefs_instance_file_read_number()_ function returns 0 if a valid integer is read from +the file and stored in _res_ or -1 in case of an error. + EXAMPLE ------- [source,c] @@ -123,6 +138,30 @@ struct tracefs_instance *inst = tracefs_instance_create("foo"); tracefs_instance_destroy(inst); else tracefs_instance_free(inst); + ... + + long long int res; + if (tracefs_instance_file_read_number(NULL, "tracing_on", &res) == 0) { + if (res == 0) { + /* tracing is disabled in the top instance */ + } else if (res == 1) { + /* tracing is enabled in the top instance */ + } else { + /* Unknown tracing state of the top instance */ + } + } else { + /* Failed to read integer from tracing_on file */ + } + + ... + + int fd; + fd = tracefs_instance_file_open(NULL, "tracing_on", O_WRONLY); + if (fd >= 0) { + /* Got file descriptor to the tracing_on file from the top instance for writing */ + ... + close(fd); + } -- FILES ----- diff --git a/Documentation/libtracefs.txt b/Documentation/libtracefs.txt index bf3882f..0350416 100644 --- a/Documentation/libtracefs.txt +++ b/Documentation/libtracefs.txt @@ -25,8 +25,10 @@ Trace instances: bool *tracefs_dir_exists*(struct tracefs_instance pass:[*]_instance_, char pass:[*]_name_); char pass:[*]*tracefs_instance_get_file*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_); char pass:[*]*tracefs_instance_get_dir*(struct tracefs_instance pass:[*]_instance_); + int *tracefs_instance_file_open*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int _mode_); int *tracefs_instance_file_write*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, const char pass:[*]_str_); char pass:[*]*tracefs_instance_file_read*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, int pass:[*]_psize_); + int *tracefs_instance_file_read_number*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_, long long int pass:[*]_res_); const char pass:[*]*tracefs_instance_get_name*(struct tracefs_instance pass:[*]_instance_); int *tracefs_instances_walk*(int (pass:[*]_callback_)(const char pass:[*], void pass:[*]), void pass:[*]_context)_; bool *tracefs_instance_exists*(const char pass:[*]_name_);