From patchwork Tue Jul 17 06:39:54 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: john stultz X-Patchwork-Id: 10026 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 A7DEE23E56 for ; Tue, 17 Jul 2012 06:41:18 +0000 (UTC) Received: from mail-yw0-f52.google.com (mail-yw0-f52.google.com [209.85.213.52]) by fiordland.canonical.com (Postfix) with ESMTP id 5C34BA181CC for ; Tue, 17 Jul 2012 06:41:18 +0000 (UTC) Received: by yhpp61 with SMTP id p61so50830yhp.11 for ; Mon, 16 Jul 2012 23:41:17 -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=CgR02OGjntTwDwuCTWZ4RBPbql9NxJrhL/GQlPxbXZc=; b=SWPlLBC4RGyybqkcdkmQH0CCGcGwATzKtucOvU6b4oR8lLO5LvxI0R57qQPOhmSDba KDDYJrEzjT195ZUI5kjR0maJdgsYwpFBel+L6PZf/mAntCe+JZCGO3rLzK0TWcYgqcZK W5IjBBzqET8JMgvgfvxv5NqXtz5115HO0126Jb2lanLKOPYATRpXSCbEezLTevzc5kpn JDRAKwe1pctmDHE/E0gLx1jjpKOkB47YDJPsftgXqAMuvoJNTVnJhdWUrH5ivU/nVSpR bRjAaHXW1/+Njs1OmQlkJYFfHCL4dJxArJTg/Fkj/x4xpVnFfhrooAiRUqswAQL49Sq6 51fw== Received: by 10.43.63.140 with SMTP id xe12mr596920icb.57.1342507277533; Mon, 16 Jul 2012 23:41:17 -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 lc2csp15755ibb; Mon, 16 Jul 2012 23:41:17 -0700 (PDT) Received: by 10.50.94.228 with SMTP id df4mr412847igb.34.1342507276923; Mon, 16 Jul 2012 23:41:16 -0700 (PDT) Received: from e8.ny.us.ibm.com (e8.ny.us.ibm.com. 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Violators will be prosecuted; Tue, 17 Jul 2012 02:40:12 -0400 Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id CE6FF6E804D for ; Tue, 17 Jul 2012 02:40:11 -0400 (EDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q6H6eBGq384078 for ; Tue, 17 Jul 2012 02:40:11 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q6HCB4gN020921 for ; Tue, 17 Jul 2012 08:11:04 -0400 Received: from kernel.stglabs.ibm.com (kernel.stglabs.ibm.com [9.114.214.19]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q6HCB4cB020889; Tue, 17 Jul 2012 08:11:04 -0400 From: John Stultz To: stable@vger.kernel.org Cc: Thomas Gleixner , John Stultz , Prarit Bhargava , Linux Kernel Subject: [PATCH 5/7] 3.4.x: timekeeping: Provide hrtimer update function Date: Tue, 17 Jul 2012 02:39:54 -0400 Message-Id: <1342507196-54327-6-git-send-email-johnstul@us.ibm.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1342507196-54327-1-git-send-email-johnstul@us.ibm.com> References: <1342507196-54327-1-git-send-email-johnstul@us.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12071706-9360-0000-0000-0000087851DD X-Gm-Message-State: ALoCoQllCl5u62nJb54CykPKHO+Pjr1J43ZGwRFaLSeZpZmPRvUcnusYEr4A8HKd8f7maqWwR+mH 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 615ec8d..62e12c3 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1273,6 +1273,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim, } while (read_seqretry(&timekeeper.lock, seq)); } +#ifdef CONFIG_HIGH_RES_TIMERS +/** + * ktime_get_update_offsets - hrtimer helper + * @offs_real: pointer to storage for monotonic -> realtime offset + * @offs_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 *offs_real, ktime_t *offs_boot) +{ + ktime_t now; + unsigned int seq; + u64 secs, nsecs; + + do { + seq = read_seqbegin(&timekeeper.lock); + + secs = timekeeper.xtime.tv_sec; + nsecs = timekeeper.xtime.tv_nsec; + nsecs += timekeeping_get_ns(); + /* If arch requires, add in gettimeoffset() */ + nsecs += arch_gettimeoffset(); + + *offs_real = timekeeper.offs_real; + *offs_boot = timekeeper.offs_boot; + } while (read_seqretry(&timekeeper.lock, seq)); + + now = ktime_add_ns(ktime_set(secs, 0), nsecs); + now = ktime_sub(now, *offs_real); + return now; +} +#endif + /** * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format */