From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933125Ab2JAXCO (ORCPT ); Mon, 1 Oct 2012 19:02:14 -0400 Received: from 1wt.eu ([62.212.114.60]:35507 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932976Ab2JAXCL (ORCPT ); Mon, 1 Oct 2012 19:02:11 -0400 Message-Id: <20121001225158.122542529@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 02 Oct 2012 00:52:09 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: John Stultz , Peter Zijlstra , Prarit Bhargava , Thomas Gleixner , Willy Tarreau Subject: [ 012/180] 2.6.32.x: hrtimer: Provide clock_was_set_delayed() In-Reply-To: <6a854f579a99b4fe2efaca1057e8ae22@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: John Stultz 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 Reported-by: Jan Engelhardt Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Prarit Bhargava Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner Cc: Prarit Bhargava Cc: Thomas Gleixner Cc: Linux Kernel Signed-off-by: John Stultz Signed-off-by: Willy Tarreau --- include/linux/hrtimer.h | 7 +++++++ kernel/hrtimer.c | 20 ++++++++++++++++++++ 2 files changed, 27 insertions(+), 0 deletions(-) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 040b679..a7f48af 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -159,6 +159,7 @@ struct hrtimer_clock_base { * and timers * @clock_base: array of clock bases for this cpu * @curr_timer: the timer which is executing a callback right now + * @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 @@ -171,6 +172,7 @@ struct hrtimer_clock_base { struct hrtimer_cpu_base { spinlock_t lock; struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES]; + unsigned int clock_was_set; #ifdef CONFIG_HIGH_RES_TIMERS ktime_t expires_next; int hres_active; @@ -280,6 +282,8 @@ 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 @@ -308,6 +312,9 @@ static inline int hrtimer_is_hres_active(struct hrtimer *timer) { return 0; } + +static inline void clock_was_set_delayed(void) { } + #endif extern ktime_t ktime_get(void); diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index a6e9d00..c4acec7 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -738,6 +738,19 @@ 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; } @@ -1393,6 +1406,13 @@ 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(); } -- 1.7.2.1.45.g54fbc