From patchwork Tue Apr 5 07:23:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557927 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 C4C4BC46467 for ; Tue, 5 Apr 2022 08:37:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242212AbiDEIhP (ORCPT ); Tue, 5 Apr 2022 04:37:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238750AbiDEITV (ORCPT ); Tue, 5 Apr 2022 04:19:21 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1296072479; Tue, 5 Apr 2022 01:09:26 -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 AEB4FB81A37; Tue, 5 Apr 2022 08:09:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 198EFC385A1; Tue, 5 Apr 2022 08:09:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649146163; bh=VKULRthVlARqIBKJxJT2Bjr2YzjzP/RKQZuE96zqOAA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N3ixLPA76aNDldICDPNfkPBxrET5DdzIBHzNvDflW0qb06jbjJRAHckArjg/ssq1o u0FNluG7NeGn3C8+pcn/e8N3NdGKIY8xoU56a1O1u5vyOlMrEyyAzFw6Pidqx3Ww79 AnrvUoMp3B/Fa5n7gbV9qzb9kq1Xu9m5XssWfIbs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?utf-8?q?Niklas_S=C3=B6derlund?= , Simon Horman , Daniel Borkmann , Sasha Levin Subject: [PATCH 5.17 0664/1126] samples/bpf, xdpsock: Fix race when running for fix duration of time Date: Tue, 5 Apr 2022 09:23:31 +0200 Message-Id: <20220405070427.118455998@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Niklas Söderlund [ Upstream commit 8fa42d78f6354bb96ad3a079dcbef528ca9fa9e0 ] When running xdpsock for a fix duration of time before terminating using --duration=, there is a race condition that may cause xdpsock to terminate immediately. When running for a fixed duration of time the check to determine when to terminate execution is in is_benchmark_done() and is being executed in the context of the poller thread, if (opt_duration > 0) { unsigned long dt = (get_nsecs() - start_time); if (dt >= opt_duration) benchmark_done = true; } However start_time is only set after the poller thread have been created. This leaves a small window when the poller thread is starting and calls is_benchmark_done() for the first time that start_time is not yet set. In that case start_time have its initial value of 0 and the duration check fails as it do not correlate correctly for the applications start time and immediately sets benchmark_done which in turn terminates the xdpsock application. Fix this by setting start_time before creating the poller thread. Fixes: d3f11b018f6c ("samples/bpf: xdpsock: Add duration option to specify how long to run") Signed-off-by: Niklas Söderlund Signed-off-by: Simon Horman Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220315102948.466436-1-niklas.soderlund@corigine.com Signed-off-by: Sasha Levin --- samples/bpf/xdpsock_user.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c index aa50864e4415..9f3446af50ce 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -1984,15 +1984,15 @@ int main(int argc, char **argv) setlocale(LC_ALL, ""); + prev_time = get_nsecs(); + start_time = prev_time; + if (!opt_quiet) { ret = pthread_create(&pt, NULL, poller, NULL); if (ret) exit_with_error(ret); } - prev_time = get_nsecs(); - start_time = prev_time; - /* Configure sched priority for better wake-up accuracy */ memset(&schparam, 0, sizeof(schparam)); schparam.sched_priority = opt_schprio;