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Subject[GIT pull] timer updates for 3.17
Linus,

please pull the latest timers-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-urgent-for-linus

Three fixlets from the timer departement:

- Update the timekeeper before updating vsyscall and pvclock. This
fixes the kvm-clock regression reported by Chris and Paolo.

- Use the proper irq work interface from NMI. This fixes the
regression reported by Catalin and Dave.

- Clarify the compat_nanosleep error handling mechanism to avoid
future confusion.

Thanks,

tglx

------------------>
Frederic Weisbecker (1):
nohz: Restore NMI safe local irq work for local nohz kick

Thomas Gleixner (2):
compat: nanosleep: Clarify error handling
timekeeping: Update timekeeper before updating vsyscall and pvclock


include/linux/tick.h | 7 +------
kernel/compat.c | 24 +++++++++++++++++++++---
kernel/time/tick-sched.c | 14 ++++++++++++++
kernel/time/timekeeping.c | 5 +++--
4 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 059052306831..9a82c7dc3fdd 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -183,13 +183,8 @@ static inline bool tick_nohz_full_cpu(int cpu)

extern void tick_nohz_init(void);
extern void __tick_nohz_full_check(void);
+extern void tick_nohz_full_kick(void);
extern void tick_nohz_full_kick_cpu(int cpu);
-
-static inline void tick_nohz_full_kick(void)
-{
- tick_nohz_full_kick_cpu(smp_processor_id());
-}
-
extern void tick_nohz_full_kick_all(void);
extern void __tick_nohz_task_switch(struct task_struct *tsk);
#else
diff --git a/kernel/compat.c b/kernel/compat.c
index 633394f442f8..ebb3c369d03d 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -226,7 +226,7 @@ static long compat_nanosleep_restart(struct restart_block *restart)
ret = hrtimer_nanosleep_restart(restart);
set_fs(oldfs);

- if (ret) {
+ if (ret == -ERESTART_RESTARTBLOCK) {
rmtp = restart->nanosleep.compat_rmtp;

if (rmtp && compat_put_timespec(&rmt, rmtp))
@@ -256,7 +256,26 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
HRTIMER_MODE_REL, CLOCK_MONOTONIC);
set_fs(oldfs);

- if (ret) {
+ /*
+ * hrtimer_nanosleep() can only return 0 or
+ * -ERESTART_RESTARTBLOCK here because:
+ *
+ * - we call it with HRTIMER_MODE_REL and therefor exclude the
+ * -ERESTARTNOHAND return path.
+ *
+ * - we supply the rmtp argument from the task stack (due to
+ * the necessary compat conversion. So the update cannot
+ * fail, which excludes the -EFAULT return path as well. If
+ * it fails nevertheless we have a bigger problem and wont
+ * reach this place anymore.
+ *
+ * - if the return value is 0, we do not have to update rmtp
+ * because there is no remaining time.
+ *
+ * We check for -ERESTART_RESTARTBLOCK nevertheless if the
+ * core implementation decides to return random nonsense.
+ */
+ if (ret == -ERESTART_RESTARTBLOCK) {
struct restart_block *restart
= &current_thread_info()->restart_block;

@@ -266,7 +285,6 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
if (rmtp && compat_put_timespec(&rmt, rmtp))
return -EFAULT;
}
-
return ret;
}

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 99aa6ee3908f..f654a8a298fa 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -225,6 +225,20 @@ static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {
};

/*
+ * Kick this CPU if it's full dynticks in order to force it to
+ * re-evaluate its dependency on the tick and restart it if necessary.
+ * This kick, unlike tick_nohz_full_kick_cpu() and tick_nohz_full_kick_all(),
+ * is NMI safe.
+ */
+void tick_nohz_full_kick(void)
+{
+ if (!tick_nohz_full_cpu(smp_processor_id()))
+ return;
+
+ irq_work_queue(&__get_cpu_var(nohz_full_kick_work));
+}
+
+/*
* Kick the CPU if it's full dynticks in order to force it to
* re-evaluate its dependency on the tick and restart it if necessary.
*/
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index fb4a9c2cf8d9..ec1791fae965 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -442,11 +442,12 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
tk->ntp_error = 0;
ntp_clear();
}
- update_vsyscall(tk);
- update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);

tk_update_ktime_data(tk);

+ update_vsyscall(tk);
+ update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
+
if (action & TK_MIRROR)
memcpy(&shadow_timekeeper, &tk_core.timekeeper,
sizeof(tk_core.timekeeper));

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