This is a note to let you know that I've just added the patch titled
hrtimer: Provide clock_was_set_delayed()
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:
hrtimer-provide-clock_was_set_delayed.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 14:22:23 2012
From: John Stultz <johns...@us.ibm.com>
Date: Tue, 17 Jul 2012 02:39:50 -0400
Subject: hrtimer: Provide clock_was_set_delayed()
To: sta...@vger.kernel.org
Cc: John Stultz <johns...@us.ibm.com>, Thomas Gleixner <t...@linutronix.de>,
Prarit Bhargava <pra...@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Message-ID: <1342507196-54327-2-git-send-email-johns...@us.ibm.com>
From: John Stultz <johns...@us.ibm.com>
This is a backport of f55a6faa384304c89cfef162768e88374d3312cb
clock_was_set() cannot be called from hard interrupt context because
it calls on_each_cpu().
For fixing the widely reported leap seconds issue it is necessary to
call it from hard interrupt context, i.e. the timer tick code, which
does the timekeeping updates.
Provide a new function which denotes it in the hrtimer cpu base
structure of the cpu on which it is called and raise the hrtimer
softirq. We then execute the clock_was_set() notificiation from
softirq context in run_hrtimer_softirq(). The hrtimer softirq is
rarely used, so polling the flag there is not a performance issue.
[ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get
rid of all this ifdeffery ASAP ]
Signed-off-by: John Stultz <johns...@us.ibm.com>
Reported-by: Jan Engelhardt <jeng...@inai.de>
Reviewed-by: Ingo Molnar <mi...@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijls...@chello.nl>
Acked-by: Prarit Bhargava <pra...@redhat.com>
Link:
http://lkml.kernel.org/r/1341960205-56738-2-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 | 9 ++++++++-
kernel/hrtimer.c | 20 ++++++++++++++++++++
2 files changed, 28 insertions(+), 1 deletion(-)
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -165,6 +165,7 @@ enum hrtimer_base_type {
* @lock: lock protecting the base and associated clock bases
* and timers
* @active_bases: Bitfield to mark bases with active timers
+ * @clock_was_set: Indicates that clock was set from irq context.
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
* @hres_active: State of high resolution mode
@@ -177,7 +178,8 @@ enum hrtimer_base_type {
*/
struct hrtimer_cpu_base {
raw_spinlock_t lock;
- unsigned long active_bases;
+ unsigned int active_bases;
+ unsigned int clock_was_set;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
int hres_active;
@@ -286,6 +288,8 @@ extern void hrtimer_peek_ahead_timers(vo
# define MONOTONIC_RES_NSEC HIGH_RES_NSEC
# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
+extern void clock_was_set_delayed(void);
+
#else
# define MONOTONIC_RES_NSEC LOW_RES_NSEC
@@ -306,6 +310,9 @@ static inline int hrtimer_is_hres_active
{
return 0;
}
+
+static inline void clock_was_set_delayed(void) { }
+
#endif
extern void clock_was_set(void);
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -717,6 +717,19 @@ static int hrtimer_switch_to_hres(void)
return 1;
}
+/*
+ * Called from timekeeping code to reprogramm the hrtimer interrupt
+ * device. If called from the timer interrupt context we defer it to
+ * softirq context.
+ */
+void clock_was_set_delayed(void)
+{
+ struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+ cpu_base->clock_was_set = 1;
+ __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+}
+
#else
static inline int hrtimer_hres_active(void) { return 0; }
@@ -1395,6 +1408,13 @@ void hrtimer_peek_ahead_timers(void)
static void run_hrtimer_softirq(struct softirq_action *h)
{
+ struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+ if (cpu_base->clock_was_set) {
+ cpu_base->clock_was_set = 0;
+ clock_was_set();
+ }
+
hrtimer_peek_ahead_timers();
}
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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