From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757065Ab2GQVur (ORCPT ); Tue, 17 Jul 2012 17:50:47 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:34459 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756985Ab2GQVul (ORCPT ); Tue, 17 Jul 2012 17:50:41 -0400 From: John Stultz To: stable@vger.kernel.org Cc: Thomas Gleixner , John Stultz , Prarit Bhargava , Linux Kernel Subject: [PATCH 09/11] 2.6.34.x: timekeeping: Provide hrtimer update function Date: Tue, 17 Jul 2012 17:49:29 -0400 Message-Id: <1342561771-55678-10-git-send-email-johnstul@us.ibm.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1342561771-55678-1-git-send-email-johnstul@us.ibm.com> References: <1342561771-55678-1-git-send-email-johnstul@us.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12071721-1780-0000-0000-0000077E4115 X-IBM-ISS-SpamDetectors: X-IBM-ISS-DetailInfo: BY=3.00000287; HX=3.00000193; KW=3.00000007; PH=3.00000001; SC=3.00000004; SDB=6.00157490; UDB=6.00035526; UTC=2012-07-17 21:50:38 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 2 +- kernel/time/timekeeping.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 1 deletion(-) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 0325598..887d1e7 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -319,7 +319,7 @@ static inline void clock_was_set_delayed(void) { } extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); - +extern ktime_t ktime_get_update_offsets(ktime_t *offs_real); DECLARE_PER_CPU(struct tick_device, tick_cpu_device); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 3d443b4..0b4f6d1 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -969,3 +969,35 @@ struct timespec get_monotonic_coarse(void) now.tv_nsec + mono.tv_nsec); return now; } + +#ifdef CONFIG_HIGH_RES_TIMERS +/** + * ktime_get_update_offsets - hrtimer helper + * @real: pointer to storage for monotonic -> realtime 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 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; + } while (read_seqretry(&xtime_lock, seq)); + + now = ktime_add_ns(ktime_set(secs, 0), nsecs); + now = ktime_sub(now, *real); + return now; +} +#endif -- 1.7.9.5