From patchwork Thu Mar 2 11:46:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tero Kristo X-Patchwork-Id: 13157161 X-Patchwork-Delegate: bpf@iogearbox.net 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 79BADC7EE30 for ; Thu, 2 Mar 2023 11:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229864AbjCBLqd (ORCPT ); Thu, 2 Mar 2023 06:46:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229835AbjCBLqc (ORCPT ); Thu, 2 Mar 2023 06:46:32 -0500 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6220231D8; Thu, 2 Mar 2023 03:46:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1677757591; x=1709293591; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=/uRUelVZU3Q6oGhZ0g8qpAC23v6y/WT8NF4OlN7AJZ4=; b=SKAqhzQIj2ZQupsdsptP8OySuBGuV3YQIy/QanlwBwEuprTR/Fq5k1MQ jYCatUZZpGoSkne6pob3y2+62UYciCxv9rTY2BMhQjwXU+3AYhTO/efbP BDt+cnopcm/Axj4B8u1bCwafVKvRc/I0hfURt4WXUUvoA/ehdYjzjVIuO RH8MxvOWYAmE7W57+p6kWWLWv7BanwX6NsNgYO4gaj+ckrB1ixX5PcIWj lusqcg5GiS9SGFueOYOJJbEHTMLClEUduovEv8nUp+mQvMracDz27Tw25 NUdeuaWaDRB454xBH9516MNRi6jV/NXX/xXeBqhsu51iB8jLSYwfSdGqT Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10636"; a="332180134" X-IronPort-AV: E=Sophos;i="5.98,227,1673942400"; d="scan'208";a="332180134" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Mar 2023 03:46:31 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10636"; a="705229331" X-IronPort-AV: E=Sophos;i="5.98,227,1673942400"; d="scan'208";a="705229331" Received: from pplank-mobl1.ger.corp.intel.com (HELO tkristo-desk.bb.dnainternet.fi) ([10.251.217.71]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Mar 2023 03:46:29 -0800 From: Tero Kristo To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Artem Bityutskiy Subject: [PATCHv2 1/2] bpf: Add support for absolute value BPF timers Date: Thu, 2 Mar 2023 13:46:13 +0200 Message-Id: <20230302114614.2985072-2-tero.kristo@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230302114614.2985072-1-tero.kristo@linux.intel.com> References: <20230302114614.2985072-1-tero.kristo@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Add a new flag BPF_F_TIMER_ABS that can be passed to bpf_timer_start() to start an absolute value timer instead of the default relative value. This makes the timer expire at an exact point in time, instead of a time with latencies induced by both the BPF and timer subsystems. Suggested-by: Artem Bityutskiy Signed-off-by: Tero Kristo --- v2: - added suggested by from Artem - copied the change from include/uapi/linux/bpf.h to tools/include also include/uapi/linux/bpf.h | 15 +++++++++++++++ kernel/bpf/helpers.c | 11 +++++++++-- tools/include/uapi/linux/bpf.h | 15 +++++++++++++++ 3 files changed, 39 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 464ca3f01fe7..7f5b71847984 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4951,6 +4951,12 @@ union bpf_attr { * different maps if key/value layout matches across maps. * Every bpf_timer_set_callback() can have different callback_fn. * + * *flags* can be one of: + * + * **BPF_F_TIMER_ABS** + * Start the timer in absolute expire value instead of the + * default relative one. + * * Return * 0 on success. * **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier @@ -7050,4 +7056,13 @@ struct bpf_core_relo { enum bpf_core_relo_kind kind; }; +/* + * Flags to control bpf_timer_start() behaviour. + * - BPF_F_TIMER_ABS: Timeout passed is absolute time, by default it is + * relative to current time. + */ +enum { + BPF_F_TIMER_ABS = (1ULL << 0), +}; + #endif /* _UAPI__LINUX_BPF_H__ */ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index af30c6cbd65d..924849d89828 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1253,10 +1253,11 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla { struct bpf_hrtimer *t; int ret = 0; + enum hrtimer_mode mode; if (in_nmi()) return -EOPNOTSUPP; - if (flags) + if (flags > BPF_F_TIMER_ABS) return -EINVAL; __bpf_spin_lock_irqsave(&timer->lock); t = timer->timer; @@ -1264,7 +1265,13 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla ret = -EINVAL; goto out; } - hrtimer_start(&t->timer, ns_to_ktime(nsecs), HRTIMER_MODE_REL_SOFT); + + if (flags & BPF_F_TIMER_ABS) + mode = HRTIMER_MODE_ABS_SOFT; + else + mode = HRTIMER_MODE_REL_SOFT; + + hrtimer_start(&t->timer, ns_to_ktime(nsecs), mode); out: __bpf_spin_unlock_irqrestore(&timer->lock); return ret; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 464ca3f01fe7..7f5b71847984 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4951,6 +4951,12 @@ union bpf_attr { * different maps if key/value layout matches across maps. * Every bpf_timer_set_callback() can have different callback_fn. * + * *flags* can be one of: + * + * **BPF_F_TIMER_ABS** + * Start the timer in absolute expire value instead of the + * default relative one. + * * Return * 0 on success. * **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier @@ -7050,4 +7056,13 @@ struct bpf_core_relo { enum bpf_core_relo_kind kind; }; +/* + * Flags to control bpf_timer_start() behaviour. + * - BPF_F_TIMER_ABS: Timeout passed is absolute time, by default it is + * relative to current time. + */ +enum { + BPF_F_TIMER_ABS = (1ULL << 0), +}; + #endif /* _UAPI__LINUX_BPF_H__ */