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Koen Kooi
6203cbca5c
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net> Signed-off-by: Denys Dmytriyenko <denys@ti.com>
95 lines
3.3 KiB
Diff
95 lines
3.3 KiB
Diff
From d6cadfb2bf29a5913562d3f63c49a937bc98540d Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 10 Jul 2012 18:43:24 -0400
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Subject: [PATCH 082/109] timekeeping: Provide hrtimer update function
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This is a backport of f6c06abfb3972ad4914cef57d8348fcb2932bc3b
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To finally fix the infamous leap second issue and other race windows
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caused by functions which change the offsets between the various time
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bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
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function which atomically gets the current monotonic time and updates
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the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
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overhead. The previous patch which provides ktime_t offsets allows us
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to make this function almost as cheap as ktime_get() which is going to
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be replaced in hrtimer_interrupt().
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Ingo Molnar <mingo@kernel.org>
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Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Acked-by: Prarit Bhargava <prarit@redhat.com>
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Signed-off-by: John Stultz <johnstul@us.ibm.com>
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Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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[John Stultz: Backported to 3.2]
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Cc: Prarit Bhargava <prarit@redhat.com>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Cc: Linux Kernel <linux-kernel@vger.kernel.org>
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Signed-off-by: John Stultz <johnstul@us.ibm.com>
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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include/linux/hrtimer.h | 1 +
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kernel/time/timekeeping.c | 34 ++++++++++++++++++++++++++++++++++
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2 files changed, 35 insertions(+), 0 deletions(-)
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diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
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index c9ec940..cc07d27 100644
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--- a/include/linux/hrtimer.h
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+++ b/include/linux/hrtimer.h
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@@ -327,6 +327,7 @@ extern ktime_t ktime_get(void);
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extern ktime_t ktime_get_real(void);
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extern ktime_t ktime_get_boottime(void);
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extern ktime_t ktime_get_monotonic_offset(void);
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+extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot);
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DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
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diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
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index d5d0e5d..4938c5e 100644
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--- a/kernel/time/timekeeping.c
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+++ b/kernel/time/timekeeping.c
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@@ -1240,6 +1240,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
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} while (read_seqretry(&xtime_lock, seq));
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}
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+#ifdef CONFIG_HIGH_RES_TIMERS
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+/**
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+ * ktime_get_update_offsets - hrtimer helper
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+ * @real: pointer to storage for monotonic -> realtime offset
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+ * @_boot: pointer to storage for monotonic -> boottime offset
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+ *
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+ * Returns current monotonic time and updates the offsets
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+ * Called from hrtimer_interupt() or retrigger_next_event()
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+ */
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+ktime_t ktime_get_update_offsets(ktime_t *real, ktime_t *boot)
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+{
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+ ktime_t now;
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+ unsigned int seq;
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+ u64 secs, nsecs;
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+
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+ do {
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+ seq = read_seqbegin(&xtime_lock);
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+
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+ secs = xtime.tv_sec;
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+ nsecs = xtime.tv_nsec;
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+ nsecs += timekeeping_get_ns();
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+ /* If arch requires, add in gettimeoffset() */
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+ nsecs += arch_gettimeoffset();
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+
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+ *real = offs_real;
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+ *boot = offs_boot;
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+ } while (read_seqretry(&xtime_lock, seq));
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+
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+ now = ktime_add_ns(ktime_set(secs, 0), nsecs);
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+ now = ktime_sub(now, *real);
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+ return now;
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+}
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+#endif
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+
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/**
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* ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
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*/
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--
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1.7.7.6
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