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Biederman" X-Patchwork-Id: 1346520 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 4BVpBH51BHz9sTM for ; Tue, 18 Aug 2020 08:09:59 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729999AbgHQWJ6 (ORCPT ); Mon, 17 Aug 2020 18:09:58 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:32902 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730109AbgHQWJs (ORCPT ); Mon, 17 Aug 2020 18:09:48 -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 1k7nK6-001Gxa-RI; Mon, 17 Aug 2020 16:09:46 -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 1k7nK6-0004PB-4C; Mon, 17 Aug 2020 16:09:46 -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 17:04:12 -0500 Message-Id: <20200817220425.9389-4-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=1k7nK6-0004PB-4C; ; ; mid=<20200817220425.9389-4-ebiederm@xmission.com>; ; ; hst=in02.mta.xmission.com; ; ; ip=68.227.160.95; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX1+Nzbhdhel0ydRCsizgoz48WncZtpCAk0g= 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 sa07.xmission.com X-Spam-Level: * X-Spam-Status: No, score=1.3 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TooManySym_01,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 * [sa07 0; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: ; sa07 0; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: *;linux-kernel@vger.kernel.org X-Spam-Relay-Country: X-Spam-Timing: total 319 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 11 (3.6%), b_tie_ro: 10 (3.1%), parse: 1.23 (0.4%), extract_message_metadata: 13 (4.0%), get_uri_detail_list: 1.60 (0.5%), tests_pri_-1000: 15 (4.7%), tests_pri_-950: 1.19 (0.4%), tests_pri_-900: 1.03 (0.3%), tests_pri_-90: 55 (17.4%), check_bayes: 54 (16.9%), b_tokenize: 9 (2.8%), b_tok_get_all: 8 (2.4%), b_comp_prob: 2.3 (0.7%), b_tok_touch_all: 32 (10.0%), b_finish: 0.86 (0.3%), tests_pri_0: 210 (65.8%), check_dkim_signature: 0.80 (0.2%), check_dkim_adsp: 2.3 (0.7%), poll_dns_idle: 0.66 (0.2%), tests_pri_10: 2.1 (0.7%), tests_pri_500: 6 (1.9%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 04/17] kcmp: In kcmp_epoll_target use fget_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 Use the helper fget_task and simplify the code. As well as simplifying the code this removes one unnecessary increment of struct files_struct. This unnecessary increment of files_struct.count can result in exec unnecessarily unsharing files_struct and breaking posix locks, and it can result in fget_light having to fallback to fget reducing performance. Suggested-by: Oleg Nesterov Signed-off-by: "Eric W. Biederman" Reviewed-by: Cyrill Gorcunov --- kernel/kcmp.c | 20 ++++---------------- 1 file changed, 4 insertions(+), 16 deletions(-) diff --git a/kernel/kcmp.c b/kernel/kcmp.c index b3ff9288c6cc..87c48c0104ad 100644 --- a/kernel/kcmp.c +++ b/kernel/kcmp.c @@ -107,7 +107,6 @@ static int kcmp_epoll_target(struct task_struct *task1, { struct file *filp, *filp_epoll, *filp_tgt; struct kcmp_epoll_slot slot; - struct files_struct *files; if (copy_from_user(&slot, uslot, sizeof(slot))) return -EFAULT; @@ -116,23 +115,12 @@ static int kcmp_epoll_target(struct task_struct *task1, if (!filp) return -EBADF; - files = get_files_struct(task2); - if (!files) + filp_epoll = fget_task(task2, slot.efd); + if (!filp_epoll) return -EBADF; - spin_lock(&files->file_lock); - filp_epoll = fcheck_files(files, slot.efd); - if (filp_epoll) - get_file(filp_epoll); - else - filp_tgt = ERR_PTR(-EBADF); - spin_unlock(&files->file_lock); - put_files_struct(files); - - if (filp_epoll) { - filp_tgt = get_epoll_tfile_raw_ptr(filp_epoll, slot.tfd, slot.toff); - fput(filp_epoll); - } + filp_tgt = get_epoll_tfile_raw_ptr(filp_epoll, slot.tfd, slot.toff); + fput(filp_epoll); if (IS_ERR(filp_tgt)) return PTR_ERR(filp_tgt);