From patchwork Mon Aug 17 22:04:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 1346521 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=xmission.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BVpBQ4xLcz9sRK for ; Tue, 18 Aug 2020 08:10:06 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730147AbgHQWKE (ORCPT ); Mon, 17 Aug 2020 18:10:04 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:33034 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730109AbgHQWKB (ORCPT ); Mon, 17 Aug 2020 18:10:01 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out03.mta.xmission.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1k7nKK-001GzL-Fa; Mon, 17 Aug 2020 16:10:00 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.int.ebiederm.org) by in02.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1k7nKI-0004PB-Th; Mon, 17 Aug 2020 16:10:00 -0600 From: "Eric W. Biederman" To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, criu@openvz.org, bpf@vger.kernel.org, Linus Torvalds , Alexander Viro , Christian Brauner , Oleg Nesterov , Cyrill Gorcunov , Jann Horn , Kees Cook , =?utf-8?q?Daniel_P=2E_Berrang?= =?utf-8?b?w6k=?= , Jeff Layton , Miklos Szeredi , Matthew Wilcox , "J. Bruce Fields" , Matthew Wilcox , Trond Myklebust , Chris Wright , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , "Eric W. Biederman" Date: Mon, 17 Aug 2020 17:04:15 -0500 Message-Id: <20200817220425.9389-7-ebiederm@xmission.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <87ft8l6ic3.fsf@x220.int.ebiederm.org> References: <87ft8l6ic3.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 X-XM-SPF: eid=1k7nKI-0004PB-Th; ; ; mid=<20200817220425.9389-7-ebiederm@xmission.com>; ; ; hst=in02.mta.xmission.com; ; ; ip=68.227.160.95; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX19tqAAFzqLxCS2GoSp2VZiejTvW45zKPBA= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa04.xmission.com X-Spam-Level: ** X-Spam-Status: No, score=2.3 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TooManySym_01,T_XMDrugObfuBody_08,XMNoVowels autolearn=disabled version=3.4.2 X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * 1.5 XMNoVowels Alpha-numberic number with no vowels * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa04 0; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 1.0 T_XMDrugObfuBody_08 obfuscated drug references X-Spam-DCC: ; sa04 0; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **;linux-kernel@vger.kernel.org X-Spam-Relay-Country: X-Spam-Timing: total 1176 ms - load_scoreonly_sql: 0.11 (0.0%), signal_user_changed: 11 (0.9%), b_tie_ro: 9 (0.8%), parse: 1.82 (0.2%), extract_message_metadata: 18 (1.5%), get_uri_detail_list: 2.3 (0.2%), tests_pri_-1000: 22 (1.9%), tests_pri_-950: 1.65 (0.1%), tests_pri_-900: 1.44 (0.1%), tests_pri_-90: 71 (6.0%), check_bayes: 69 (5.8%), b_tokenize: 11 (0.9%), b_tok_get_all: 8 (0.7%), b_comp_prob: 2.9 (0.2%), b_tok_touch_all: 43 (3.7%), b_finish: 1.10 (0.1%), tests_pri_0: 1037 (88.2%), check_dkim_signature: 0.73 (0.1%), check_dkim_adsp: 3.1 (0.3%), poll_dns_idle: 0.67 (0.1%), tests_pri_10: 2.1 (0.2%), tests_pri_500: 6 (0.5%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 07/17] proc/fd: In tid_fd_mode use fcheck_task X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org When discussing[1] exec and posix file locks it was realized that none of the callers of get_files_struct fundamentally needed to call get_files_struct, and that by switching them to helper functions instead it will both simplify their code and remove unnecessary increments of files_struct.count. Those unnecessary increments can result in exec unnecessarily unsharing files_struct which breaking posix locks, and it can result in fget_light having to fallback to fget reducing system performance. Using fcheck_task instead of get_files_struct clarifies tid_fd_mode by removing a step. [1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com Suggested-by: Oleg Nesterov Signed-off-by: "Eric W. Biederman" Acked-by: Christian Brauner --- fs/proc/fd.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 81882a13212d..4048a87c51ee 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -83,18 +83,13 @@ static const struct file_operations proc_fdinfo_file_operations = { static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode) { - struct files_struct *files = get_files_struct(task); struct file *file; - if (!files) - return false; - rcu_read_lock(); - file = fcheck_files(files, fd); + file = fcheck_task(task, fd); if (file) *mode = file->f_mode; rcu_read_unlock(); - put_files_struct(files); return !!file; }