From patchwork Fri Apr 29 13:01:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12831996 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 10323C433F5 for ; Fri, 29 Apr 2022 13:01:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359667AbiD2NFO (ORCPT ); Fri, 29 Apr 2022 09:05:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350240AbiD2NFO (ORCPT ); Fri, 29 Apr 2022 09:05:14 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2DE2B0A47; Fri, 29 Apr 2022 06:01:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 67406B83548; Fri, 29 Apr 2022 13:01:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E21DC385A4; Fri, 29 Apr 2022 13:01:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651237313; bh=t2RBNUy21aj7/pi0PiAMQQGakq/Y+RKitgUzw82hPOw=; h=From:To:Cc:Subject:Date:From; b=QxWUazrsqh78I97B5LXzfVC1Pnxn/+MSOFxYVV7d3khqI1c6q92yAZqbAmiNg7+l7 6gJ3HhhsYjcNafOgqqR5hTBgTo/tllJ+4MunDtfTMM9yo94xZidTFE3AGM1aXbIGFw awChpL+0+bTErkjGHSgD2US0N4VAIwnvXim7ZfPLAZ/Fxxgirv+MYVVWEKuKaauBrF Nyu6SW8j62lBFZMCCKzVkXmc6kfnyxzanRl1rsXPrm0PTJzW+Hkquuz9xiAWxi9vwW WmkWmYALtf61JbR8Fy5VHJGHk5vrYEAjd/LTZa7ewLPt4KvdeGXUDSZteC4xv7kGAU M5Qx+tMpRK7aw== From: Daniel Bristot de Oliveira To: Steven Rostedt , linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Daniel Bristot de Oliveira , John Kacur , Daniel Wagner Subject: [PATCH v2] rtla: Remove procps-ng dependency Date: Fri, 29 Apr 2022 15:01:48 +0200 Message-Id: X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Daniel Wagner reported to me that readproc.h got deprecated. Also, while the procps-ng library was available on Fedora, it was not available on RHEL, which is a piece of evidence that it was not that used. rtla uses procps-ng only to find the PID of the tracers' workload. I used the procps-ng library to avoid reinventing the wheel. But in this case, reinventing the wheel took me less time than the time we already took trying to work around problems. Implement a function that reads /proc/ entries, checking if: - the entry is a directory - the directory name is composed only of digits (PID) - the directory contains the comm file - the comm file contains a comm that matches the tracers' workload prefix. - then return true; otherwise, return false. And use it instead of procps-ng. Changes from V1: - Use a single buffer for comm and comm_path - Cause an error in case of a too long command prefix - Do a close_dir() - Improve log messages Cc: John Kacur Cc: Steven Rostedt Fixes: b1696371d865 ("rtla: Helper functions for rtla") Reported-by: Daniel Wagner Signed-off-by: Daniel Bristot de Oliveira --- tools/tracing/rtla/Makefile | 2 +- tools/tracing/rtla/README.txt | 1 - tools/tracing/rtla/src/utils.c | 102 ++++++++++++++++++++++++++------- tools/tracing/rtla/src/utils.h | 3 +- 4 files changed, 84 insertions(+), 24 deletions(-) diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile index 5a3226e436ef..523f0a8c38c2 100644 --- a/tools/tracing/rtla/Makefile +++ b/tools/tracing/rtla/Makefile @@ -32,7 +32,7 @@ TRACEFS_HEADERS := $$($(PKG_CONFIG) --cflags libtracefs) CFLAGS := -O -g -DVERSION=\"$(VERSION)\" $(FOPTS) $(MOPTS) $(WOPTS) $(TRACEFS_HEADERS) LDFLAGS := -ggdb -LIBS := $$($(PKG_CONFIG) --libs libtracefs) -lprocps +LIBS := $$($(PKG_CONFIG) --libs libtracefs) SRC := $(wildcard src/*.c) HDR := $(wildcard src/*.h) diff --git a/tools/tracing/rtla/README.txt b/tools/tracing/rtla/README.txt index 0fbad2640b8c..4af3fd40f171 100644 --- a/tools/tracing/rtla/README.txt +++ b/tools/tracing/rtla/README.txt @@ -11,7 +11,6 @@ RTLA depends on the following libraries and tools: - libtracefs - libtraceevent - - procps It also depends on python3-docutils to compile man pages. diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c index 3bd6f64780cf..f3d562f7f14c 100644 --- a/tools/tracing/rtla/src/utils.c +++ b/tools/tracing/rtla/src/utils.c @@ -3,7 +3,7 @@ * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira */ -#include +#include #include #include #include @@ -262,43 +262,103 @@ int __set_sched_attr(int pid, struct sched_attr *attr) return 0; } + /* - * set_comm_sched_attr - set sched params to threads starting with char *comm + * procfs_is_workload_pid - check if a procfs entry contains a comm_prefix* comm + * + * Check if the procfs entry is a directory of a process, and then check if the + * process has a comm with the prefix set in char *comm_prefix. As the + * current users of this function only check for kernel threads, there is no + * need to check for the threads for the process. * - * This function uses procps to list the currently running threads and then - * set the sched_attr *attr to the threads that start with char *comm. It is + * Return: True if the proc_entry contains a comm file with comm_prefix*. + * Otherwise returns false. + */ +static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_entry) +{ + char buffer[MAX_PATH]; + int comm_fd, retval; + char*t_name; + + if (proc_entry->d_type != DT_DIR) + return 0; + + if (*proc_entry->d_name == '.') + return 0; + + /* check if the string is a pid */ + for (t_name = proc_entry->d_name; t_name; t_name++) { + if (!isdigit(*t_name)) + break; + } + + if (*t_name != '\0') + return 0; + + snprintf(buffer, MAX_PATH, "/proc/%s/comm", proc_entry->d_name); + comm_fd = open(buffer, O_RDONLY); + if (comm_fd < 0) + return 0; + + memset(buffer, 0, MAX_PATH); + retval = read(comm_fd, buffer, MAX_PATH); + + close(comm_fd); + + if (retval <= 0) + return 0; + + retval = strncmp(comm_prefix, buffer, strlen(comm_prefix)); + if (retval) + return 0; + + /* comm already have \n */ + debug_msg("Found workload pid:%s comm:%s", proc_entry->d_name, buffer); + + return 1; +} + +/* + * set_comm_sched_attr - set sched params to threads starting with char *comm_prefix + * + * This function uses procps to list the currently running threads and then set the + * sched_attr *attr to the threads that start with char *comm_prefix. It is * mainly used to set the priority to the kernel threads created by the * tracers. */ -int set_comm_sched_attr(const char *comm, struct sched_attr *attr) +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr) { - int flags = PROC_FILLCOM | PROC_FILLSTAT; - PROCTAB *ptp; - proc_t task; + struct dirent *proc_entry; + DIR *procfs; int retval; - ptp = openproc(flags); - if (!ptp) { - err_msg("error openproc()\n"); - return -ENOENT; + if (strlen(comm_prefix) >= MAX_PATH) { + err_msg("Command prefix is too long: %d < strlen(%s)\n", + MAX_PATH, comm_prefix); + exit(EINVAL); } - memset(&task, 0, sizeof(task)); + procfs = opendir("/proc"); + + while ((proc_entry = readdir(procfs))) { - while (readproc(ptp, &task)) { - retval = strncmp(comm, task.cmd, strlen(comm)); - if (retval) + retval = procfs_is_workload_pid(comm_prefix, proc_entry); + if (!retval) continue; - retval = __set_sched_attr(task.tid, attr); - if (retval) + + /* procfs_is_workload_pid confirmed it is a pid */ + retval = __set_sched_attr(atoi(proc_entry->d_name), attr); + if (retval) { + err_msg("Error setting sched attributes for pid:%s\n", proc_entry->d_name); goto out_err; - } + } - closeproc(ptp); + debug_msg("Set sched attributes for pid:%s\n", proc_entry->d_name); + } return 0; out_err: - closeproc(ptp); + closedir(procfs); return 1; } diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h index fa08e374870a..5571afd3b549 100644 --- a/tools/tracing/rtla/src/utils.h +++ b/tools/tracing/rtla/src/utils.h @@ -6,6 +6,7 @@ * '18446744073709551615\0' */ #define BUFF_U64_STR_SIZE 24 +#define MAX_PATH 1024 #define container_of(ptr, type, member)({ \ const typeof(((type *)0)->member) *__mptr = (ptr); \ @@ -53,5 +54,5 @@ struct sched_attr { }; int parse_prio(char *arg, struct sched_attr *sched_param); -int set_comm_sched_attr(const char *comm, struct sched_attr *attr); +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr); int set_cpu_dma_latency(int32_t latency);