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 ED8DFC636CD for ; Tue, 31 Jan 2023 10:29:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229991AbjAaK3z (ORCPT ); Tue, 31 Jan 2023 05:29:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231359AbjAaK3u (ORCPT ); Tue, 31 Jan 2023 05:29:50 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8E1E2DE4A; Tue, 31 Jan 2023 02:29:49 -0800 (PST) Date: Tue, 31 Jan 2023 10:29:47 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1675160988; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Mi0xskgCf7FEoeugCADqGqRpxrjV8N9iSMOx8TKwgyY=; b=o7pkl7BmSceGIKBIFG31b7hTLaYQumkypW5o134JypcNjctxCAr0wR1ByOi91tU76crIJV SyGy8x1MsBCqjc2UGUNm5HavPduD/O4w7rL02bKZpk8Dzj34kdK/EMJhmN3yIzvCglgav2 DhHPn5xrSUKnGLEBCMR6JgPeexa1tDmFy9VU3v+wUlAPHbzzLzYbRCs91Wif0vOz5E+Sst iYXR9INJHX8WJqJ8/Vsd4eBAi7PG/Oj0/1/gyw4rdv5prjHrz+u1bOg9YUvaoqJiHN//oY UcvD2GL/sin87SPiauMRj3YH4q7RYV4TEK4RfX1zRCRannJ8n1A78osCsXulwA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1675160988; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Mi0xskgCf7FEoeugCADqGqRpxrjV8N9iSMOx8TKwgyY=; b=rK0ix6KNPot4u+gCmovCg7/jzTNOV/pFJQfItjTIeJ25do+1bVazxUF8waEjCXO/lDBOOY J6cmpQOKFcCRPFBQ== From: "tip-bot2 for Davidlohr Bueso" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/core] hrtimer: Ignore slack time for RT tasks in schedule_hrtimeout_range() Cc: Davidlohr Bueso , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20230123173206.6764-3-dave@stgolabs.net> References: <20230123173206.6764-3-dave@stgolabs.net> MIME-Version: 1.0 Message-ID: <167516098750.4906.3310557441657379579.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the timers/core branch of tip: Commit-ID: 0c52310f260014d95c1310364379772cb74cf82d Gitweb: https://git.kernel.org/tip/0c52310f260014d95c1310364379772cb74cf82d Author: Davidlohr Bueso AuthorDate: Mon, 23 Jan 2023 09:32:06 -08:00 Committer: Thomas Gleixner CommitterDate: Tue, 31 Jan 2023 11:23:07 +01:00 hrtimer: Ignore slack time for RT tasks in schedule_hrtimeout_range() While in theory the timer can be triggered before expires + delta, for the cases of RT tasks they really have no business giving any lenience for extra slack time, so override any passed value by the user and always use zero for schedule_hrtimeout_range() calls. Furthermore, this is similar to what the nanosleep(2) family already does with current->timer_slack_ns. Signed-off-by: Davidlohr Bueso Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230123173206.6764-3-dave@stgolabs.net --- kernel/time/hrtimer.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 667b713..e8c0829 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -2272,7 +2272,7 @@ void __init hrtimers_init(void) /** * schedule_hrtimeout_range_clock - sleep until timeout * @expires: timeout value (ktime_t) - * @delta: slack in expires timeout (ktime_t) + * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks * @mode: timer mode * @clock_id: timer clock to be used */ @@ -2299,6 +2299,13 @@ schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta, return -EINTR; } + /* + * Override any slack passed by the user if under + * rt contraints. + */ + if (rt_task(current)) + delta = 0; + hrtimer_init_sleeper_on_stack(&t, clock_id, mode); hrtimer_set_expires_range_ns(&t.timer, *expires, delta); hrtimer_sleeper_start_expires(&t, mode); @@ -2318,7 +2325,7 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock); /** * schedule_hrtimeout_range - sleep until timeout * @expires: timeout value (ktime_t) - * @delta: slack in expires timeout (ktime_t) + * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks * @mode: timer mode * * Make the current task sleep until the given expiry time has @@ -2326,7 +2333,8 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock); * the current task state has been set (see set_current_state()). * * The @delta argument gives the kernel the freedom to schedule the - * actual wakeup to a time that is both power and performance friendly. + * actual wakeup to a time that is both power and performance friendly + * for regular (non RT/DL) tasks. * The kernel give the normal best effort behavior for "@expires+@delta", * but may decide to fire the timer earlier, but no earlier than @expires. *