From patchwork Tue Jul 17 07:05:22 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: john stultz X-Patchwork-Id: 10035 Return-Path: X-Original-To: patchwork@peony.canonical.com Delivered-To: patchwork@peony.canonical.com Received: from fiordland.canonical.com (fiordland.canonical.com [91.189.94.145]) by peony.canonical.com (Postfix) with ESMTP id 5A3BD23E1B for ; Tue, 17 Jul 2012 07:06:05 +0000 (UTC) Received: from mail-gh0-f180.google.com (mail-gh0-f180.google.com [209.85.160.180]) by fiordland.canonical.com (Postfix) with ESMTP id 29E7EA18606 for ; Tue, 17 Jul 2012 07:06:05 +0000 (UTC) Received: by mail-gh0-f180.google.com with SMTP id z12so65734ghb.11 for ; Tue, 17 Jul 2012 00:06:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-forwarded-to:x-forwarded-for:delivered-to:received-spf:from:to:cc :subject:date:message-id:x-mailer:in-reply-to:references :x-content-scanned:x-cbid:x-gm-message-state; bh=6FbzirKc76JjDUGxXhl2dz21kT0Mnwr83TMx7DNC94Y=; b=UAeKFzXMz6QoCwIkQAJHn79VMfww/4KhECbUt53x4EKllzNaOEnjUVqZuWtG6y3vDC MtJ29vAvW8eGNNbMvetQYenAydmRuVL5yIlPI0xP+/G4YdbhwFlRhBQDdZYSK1Lz9kjl aqlgxgxW0VBMSGv96QcsFRPjNbXww10nLdhqLAO67Y5MHPL3r6F2MI6x28Ng5pKsi9Kr 8ejKMuoaZUyEoMS9xuXhEgfF/gl9mnxK5deKThQisbWpoY4CmHJxYVlQeX9ttrETT513 nSDNToD/rV8YEmYB5RQ7Pf6TqpgFM/Do7nUBmX0UTvosf82rsEakEFMGUqL7Ycc1l+L7 dX9Q== Received: by 10.50.160.198 with SMTP id xm6mr503459igb.0.1342508764779; Tue, 17 Jul 2012 00:06:04 -0700 (PDT) X-Forwarded-To: linaro-patchwork@canonical.com X-Forwarded-For: patch@linaro.org linaro-patchwork@canonical.com Delivered-To: patches@linaro.org Received: by 10.231.241.2 with SMTP id lc2csp15909ibb; Tue, 17 Jul 2012 00:06:04 -0700 (PDT) Received: by 10.60.9.193 with SMTP id c1mr1702411oeb.47.1342508764188; Tue, 17 Jul 2012 00:06:04 -0700 (PDT) Received: from e36.co.us.ibm.com (e36.co.us.ibm.com. 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Violators will be prosecuted; Tue, 17 Jul 2012 01:05:42 -0600 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id CFDC1C90058 for ; Tue, 17 Jul 2012 03:05:41 -0400 (EDT) Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q6H75f7N372252 for ; Tue, 17 Jul 2012 03:05:41 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q6H75eQe016328 for ; Tue, 17 Jul 2012 03:05:40 -0400 Received: from kernel.stglabs.ibm.com (kernel.stglabs.ibm.com [9.114.214.19]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q6H75aBR015997; Tue, 17 Jul 2012 03:05:37 -0400 From: John Stultz To: stable@vger.kernel.org Cc: Thomas Gleixner , John Stultz , Prarit Bhargava , Linux Kernel Subject: [PATCH 09/11] 3.2.x: timekeeping: Provide hrtimer update function Date: Tue, 17 Jul 2012 03:05:22 -0400 Message-Id: <1342508724-14527-10-git-send-email-johnstul@us.ibm.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1342508724-14527-1-git-send-email-johnstul@us.ibm.com> References: <1342508724-14527-1-git-send-email-johnstul@us.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12071707-7606-0000-0000-0000020F60F5 X-Gm-Message-State: ALoCoQlscG0yh+HqWGUkU4D4mRYVC3DJ3Nm2JVyU9aAEAsGDAOT9BpQUX2xdCE0+iWMN/jSkoAkg From: Thomas Gleixner This is a backport of f6c06abfb3972ad4914cef57d8348fcb2932bc3b To finally fix the infamous leap second issue and other race windows caused by functions which change the offsets between the various time bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a function which atomically gets the current monotonic time and updates the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic overhead. The previous patch which provides ktime_t offsets allows us to make this function almost as cheap as ktime_get() which is going to be replaced in hrtimer_interrupt(). Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Prarit Bhargava Cc: stable@vger.kernel.org Signed-off-by: John Stultz Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner Cc: Prarit Bhargava Cc: Thomas Gleixner Cc: Linux Kernel Signed-off-by: John Stultz --- include/linux/hrtimer.h | 1 + kernel/time/timekeeping.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index c9ec940..cc07d27 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -327,6 +327,7 @@ extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); extern ktime_t ktime_get_boottime(void); extern ktime_t ktime_get_monotonic_offset(void); +extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot); DECLARE_PER_CPU(struct tick_device, tick_cpu_device); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index d5d0e5d..4938c5e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1240,6 +1240,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim, } while (read_seqretry(&xtime_lock, seq)); } +#ifdef CONFIG_HIGH_RES_TIMERS +/** + * ktime_get_update_offsets - hrtimer helper + * @real: pointer to storage for monotonic -> realtime offset + * @_boot: pointer to storage for monotonic -> boottime offset + * + * Returns current monotonic time and updates the offsets + * Called from hrtimer_interupt() or retrigger_next_event() + */ +ktime_t ktime_get_update_offsets(ktime_t *real, ktime_t *boot) +{ + ktime_t now; + unsigned int seq; + u64 secs, nsecs; + + do { + seq = read_seqbegin(&xtime_lock); + + secs = xtime.tv_sec; + nsecs = xtime.tv_nsec; + nsecs += timekeeping_get_ns(); + /* If arch requires, add in gettimeoffset() */ + nsecs += arch_gettimeoffset(); + + *real = offs_real; + *boot = offs_boot; + } while (read_seqretry(&xtime_lock, seq)); + + now = ktime_add_ns(ktime_set(secs, 0), nsecs); + now = ktime_sub(now, *real); + return now; +} +#endif + /** * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format */