This is a note to let you know that I've just added the patch titled
timekeeping: Provide hrtimer update function
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timekeeping-provide-hrtimer-update-function.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@vger.kernel.org> know about it.
>From johns...@us.ibm.com Tue Jul 17 14:27:23 2012
From: John Stultz <johns...@us.ibm.com>
Date: Tue, 17 Jul 2012 02:39:54 -0400
Subject: timekeeping: Provide hrtimer update function
To: sta...@vger.kernel.org
Cc: Thomas Gleixner <t...@linutronix.de>, John Stultz <johns...@us.ibm.com>,
Prarit Bhargava <pra...@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342507196-54327-6-git-send-email-johns...@us.ibm.com>
From: Thomas Gleixner <t...@linutronix.de>
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 <t...@linutronix.de>
Reviewed-by: Ingo Molnar <mi...@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijls...@chello.nl>
Acked-by: Prarit Bhargava <pra...@redhat.com>
Signed-off-by: John Stultz <johns...@us.ibm.com>
Link:
http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johns...@us.ibm.com
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Prarit Bhargava <pra...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: John Stultz <johns...@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
include/linux/hrtimer.h | 1 +
kernel/time/timekeeping.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
--- 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);
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1273,6 +1273,40 @@ void get_xtime_and_monotonic_and_sleep_o
} 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
*/
Patches currently in stable-queue which might be from johns...@us.ibm.com are
queue-3.4/timekeeping-fix-leapsecond-triggered-load-spike-issue.patch
queue-3.4/hrtimer-update-hrtimer-base-offsets-each-hrtimer_interrupt.patch
queue-3.4/timekeeping-add-missing-update-call-in-timekeeping_resume.patch
queue-3.4/hrtimers-move-lock-held-region-in-hrtimer_interrupt.patch
queue-3.4/hrtimer-provide-clock_was_set_delayed.patch
queue-3.4/timekeeping-provide-hrtimer-update-function.patch
queue-3.4/timekeeping-maintain-ktime_t-based-offsets-for-hrtimers.patch
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