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Violators will be prosecuted; Tue, 17 Jul 2012 12:06:29 -0600 Received: from d03relay01.boulder.ibm.com (d03relay01.boulder.ibm.com [9.17.195.226]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id 874953E40059 for ; Tue, 17 Jul 2012 18:06:27 +0000 (WET) Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay01.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q6HI6CvB198444 for ; Tue, 17 Jul 2012 12:06:13 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q6HI6Bbx019638 for ; Tue, 17 Jul 2012 12:06:11 -0600 Received: from kernel.stglabs.ibm.com (kernel.stglabs.ibm.com [9.114.214.19]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q6HI60xn018372; Tue, 17 Jul 2012 12:06:10 -0600 From: John Stultz To: stable@vger.kernel.org Cc: Thomas Gleixner , John Stultz , Prarit Bhargava , Linux Kernel Subject: [PATCH 09/11] 2.6.35.x: timekeeping: Provide hrtimer update function Date: Tue, 17 Jul 2012 14:05:40 -0400 Message-Id: <1342548342-19683-10-git-send-email-johnstul@us.ibm.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1342548342-19683-1-git-send-email-johnstul@us.ibm.com> References: <1342548342-19683-1-git-send-email-johnstul@us.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12071718-2398-0000-0000-00000892FF90 X-Gm-Message-State: ALoCoQkghmrkA6VkZWJPMF72d9/mJAfXenaRsXloN6UnH7xceAZT9RD9mJS4LHbvJnHtHXhp3E81 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 39d5222..568d88f 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 1f8140e..2461fe4 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -976,3 +976,35 @@ 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