From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758337Ab3FTTRF (ORCPT ); Thu, 20 Jun 2013 15:17:05 -0400 Received: from smtp.citrix.com ([66.165.176.89]:43320 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758239Ab3FTTQi (ORCPT ); Thu, 20 Jun 2013 15:16:38 -0400 X-IronPort-AV: E=Sophos;i="4.87,906,1363132800"; d="scan'208";a="32470383" From: David Vrabel To: CC: David Vrabel , Konrad Rzeszutek Wilk , , John Stultz , Thomas Gleixner Subject: [PATCH 2/4] time: add a notifier chain for when the system time is stepped Date: Thu, 20 Jun 2013 20:16:30 +0100 Message-ID: <1371755792-25962-3-git-send-email-david.vrabel@citrix.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1371755792-25962-1-git-send-email-david.vrabel@citrix.com> References: <1371755792-25962-1-git-send-email-david.vrabel@citrix.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Vrabel The high resolution timer code gets notified of step changes to the system time with clock_was_set() or clock_was_set_delayed() calls. If other parts of the kernel require similar notification there is no clear place to hook into. Add a clock_was_set atomic notifier chain (clock_was_set_notifier_list) and call this in place of clock_was_set(). If the timekeeping locks are held, the calls are deferred to a new tasklet. The hrtimer code adds a notifier block to this chain and uses it to call (the now internal) clock_was_set(). Since the timekeeping code does not call the chain from the timer irq clock_was_set_delayed() and associated code can be removed. For the delayed case, clock_was_set() used to be called at the beginning of the hrtimer softirq and now it is called from a tasklet. The tasklet softirq will be called before the hrtimer one so this should give the same behaviour. Signed-off-by: David Vrabel Cc: Thomas Gleixner --- include/linux/hrtimer.h | 7 ------- include/linux/time.h | 7 +++++++ kernel/hrtimer.c | 34 +++++++++++++--------------------- kernel/time/timekeeping.c | 39 ++++++++++++++++++++++++++++++--------- 4 files changed, 50 insertions(+), 37 deletions(-) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 13df0fa..45e30f6 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -166,7 +166,6 @@ 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 @@ -180,7 +179,6 @@ enum hrtimer_base_type { struct hrtimer_cpu_base { raw_spinlock_t lock; unsigned int active_bases; - unsigned int clock_was_set; #ifdef CONFIG_HIGH_RES_TIMERS ktime_t expires_next; int hres_active; @@ -289,8 +287,6 @@ extern void hrtimer_peek_ahead_timers(void); # 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 @@ -312,11 +308,8 @@ static inline int hrtimer_is_hres_active(struct hrtimer *timer) return 0; } -static inline void clock_was_set_delayed(void) { } - #endif -extern void clock_was_set(void); #ifdef CONFIG_TIMERFD extern void timerfd_clock_was_set(void); #else diff --git a/include/linux/time.h b/include/linux/time.h index d5d229b..a0c08a7 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -184,6 +184,13 @@ extern void timekeeping_clocktai(struct timespec *ts); struct tms; extern void do_sys_times(struct tms *); +struct notifier_block; + +/* + * Notifier chain called when system time is stepped. + */ +extern int register_clock_was_set_notifier(struct notifier_block *nb); + /* * Similar to the struct tm in userspace , but it needs to be here so * that the kernel source is self contained. diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 34384b4..a853f9b 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -721,19 +721,6 @@ 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; } @@ -762,7 +749,7 @@ static inline void retrigger_next_event(void *arg) { } * resolution timer interrupts. On UP we just disable interrupts and * call the high resolution interrupt code. */ -void clock_was_set(void) +static void clock_was_set(void) { #ifdef CONFIG_HIGH_RES_TIMERS /* Retrigger the CPU local events everywhere */ @@ -1441,13 +1428,6 @@ 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(); } @@ -1785,11 +1765,23 @@ static struct notifier_block __cpuinitdata hrtimers_nb = { .notifier_call = hrtimer_cpu_notify, }; +static int hrtimer_clock_was_set_notify(struct notifier_block *self, + unsigned long action, void *data) +{ + clock_was_set(); + return NOTIFY_OK; +} + +static struct notifier_block hrtimers_clock_was_set_nb = { + .notifier_call = hrtimer_clock_was_set_notify, +}; + void __init hrtimers_init(void) { hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE, (void *)(long)smp_processor_id()); register_cpu_notifier(&hrtimers_nb); + register_clock_was_set_notifier(&hrtimers_clock_was_set_nb); #ifdef CONFIG_HIGH_RES_TIMERS open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq); #endif diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index baeeb5c..96c5c8e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -198,6 +198,30 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk) return nsec + get_arch_timeoffset(); } +static ATOMIC_NOTIFIER_HEAD(clock_was_set_notifier_list); + +int register_clock_was_set_notifier(struct notifier_block *nb) +{ + return atomic_notifier_chain_register(&clock_was_set_notifier_list, nb); +} +EXPORT_SYMBOL_GPL(register_clock_was_set_notifier); + +static void timekeeping_clock_was_set(void) +{ + atomic_notifier_call_chain(&clock_was_set_notifier_list, 0, NULL); +} + +static void timekeeping_clock_was_set_task(unsigned long d) +{ + timekeeping_clock_was_set(); +} +DECLARE_TASKLET(clock_was_set_tasklet, timekeeping_clock_was_set_task, 0); + +static void timekeeping_clock_was_set_delayed(void) +{ + tasklet_schedule(&clock_was_set_tasklet); +} + static RAW_NOTIFIER_HEAD(pvclock_gtod_chain); static void update_pvclock_gtod(struct timekeeper *tk) @@ -513,8 +537,7 @@ int do_settimeofday(const struct timespec *tv) write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - /* signal hrtimers about time change */ - clock_was_set(); + timekeeping_clock_was_set(); return 0; } @@ -557,8 +580,7 @@ error: /* even if we error out, we forwarded the time, so call update */ write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - /* signal hrtimers about time change */ - clock_was_set(); + timekeeping_clock_was_set(); return ret; } @@ -607,7 +629,7 @@ void timekeeping_set_tai_offset(s32 tai_offset) __timekeeping_set_tai_offset(tk, tai_offset); write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - clock_was_set(); + timekeeping_clock_was_set(); } /** @@ -877,8 +899,7 @@ void timekeeping_inject_sleeptime(struct timespec *delta) write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - /* signal hrtimers about time change */ - clock_was_set(); + timekeeping_clock_was_set(); } /** @@ -1260,7 +1281,7 @@ static inline void accumulate_nsecs_to_secs(struct timekeeper *tk) __timekeeping_set_tai_offset(tk, tk->tai_offset - leap); - clock_was_set_delayed(); + timekeeping_clock_was_set_delayed(); } } } @@ -1677,7 +1698,7 @@ int do_adjtimex(struct timex *txc) if (tai != orig_tai) { __timekeeping_set_tai_offset(tk, tai); - clock_was_set_delayed(); + timekeeping_clock_was_set_delayed(); } write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); -- 1.7.2.5