From d7cfb60c5cf904ecf1e0ae23ec178175b86f0d4a Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Fri, 19 Sep 2008 13:13:44 +0100 Subject: hrtimer: remove hrtimer_clock_base::get_softirq_time() Peter Zijlstra noticed this 8 months ago and I just noticed it again. hrtimer_clock_base::get_softirq_time() is currently unused in the entire tree. In fact, looking at the logs, it appears as if it was never used. Remove it. Signed-off-by: Mark McLoughlin Signed-off-by: Ingo Molnar --- include/linux/hrtimer.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/hrtimer.h') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 6d93dce61cb..1b079bd29c3 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -145,7 +145,6 @@ struct hrtimer_sleeper { * @first: pointer to the timer node which expires first * @resolution: the resolution of the clock, in nanoseconds * @get_time: function to retrieve the current time of the clock - * @get_softirq_time: function to retrieve the current time from the softirq * @softirq_time: the time when running the hrtimer queue in the softirq * @offset: offset of this clock to the monotonic base * @reprogram: function to reprogram the timer event @@ -157,7 +156,6 @@ struct hrtimer_clock_base { struct rb_node *first; ktime_t resolution; ktime_t (*get_time)(void); - ktime_t (*get_softirq_time)(void); ktime_t softirq_time; #ifdef CONFIG_HIGH_RES_TIMERS ktime_t offset; -- cgit v1.2.3-70-g09d2 From b91c4996df56fcd201f85c392a1de7bc3f6641f5 Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Fri, 19 Sep 2008 13:13:48 +0100 Subject: hrtimer: remove hrtimer_clock_base::reprogram() hrtimer_clock_base::reprogram() also appears to never have been used, so remove it. Signed-off-by: Mark McLoughlin Signed-off-by: Ingo Molnar --- include/linux/hrtimer.h | 4 ---- 1 file changed, 4 deletions(-) (limited to 'include/linux/hrtimer.h') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 1b079bd29c3..68b0196d869 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -147,7 +147,6 @@ struct hrtimer_sleeper { * @get_time: function to retrieve the current time of the clock * @softirq_time: the time when running the hrtimer queue in the softirq * @offset: offset of this clock to the monotonic base - * @reprogram: function to reprogram the timer event */ struct hrtimer_clock_base { struct hrtimer_cpu_base *cpu_base; @@ -159,9 +158,6 @@ struct hrtimer_clock_base { ktime_t softirq_time; #ifdef CONFIG_HIGH_RES_TIMERS ktime_t offset; - int (*reprogram)(struct hrtimer *t, - struct hrtimer_clock_base *b, - ktime_t n); #endif }; -- cgit v1.2.3-70-g09d2 From 1b02469088ac7a13d7e622b618b7410d0f1ce5ec Mon Sep 17 00:00:00 2001 From: Richard Kennedy Date: Mon, 22 Sep 2008 14:42:43 -0700 Subject: hrtimer: reorder struct hrtimer to save 8 bytes on 64bit builds reorder struct hrtimer to save 8 bytes on 64 bit builds when CONFIG_TIMER_STATS selected. (also removes 8 bytes from signal_struct) Signed-off-by: Richard Kennedy Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- include/linux/hrtimer.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/hrtimer.h') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 68b0196d869..8730b60c943 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -115,12 +115,12 @@ struct hrtimer { enum hrtimer_restart (*function)(struct hrtimer *); struct hrtimer_clock_base *base; unsigned long state; - enum hrtimer_cb_mode cb_mode; struct list_head cb_entry; + enum hrtimer_cb_mode cb_mode; #ifdef CONFIG_TIMER_STATS + int start_pid; void *start_site; char start_comm[16]; - int start_pid; #endif }; -- cgit v1.2.3-70-g09d2 From b00c1a99e7758f794923c61e5cd55268d61c9469 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 29 Sep 2008 15:44:46 +0200 Subject: hrtimer: mark migration state Impact: during migration active hrtimers can be seen as inactive The migration code removes the hrtimers from the queues of the dead CPU and sets the state temporary to INACTIVE. The enqueue code sets it to ACTIVE/PENDING again. Prevent that the wrong state can be seen by using a separate migration state bit. Signed-off-by: Thomas Gleixner --- include/linux/hrtimer.h | 4 +++- kernel/hrtimer.c | 12 ++++++++++-- 2 files changed, 13 insertions(+), 3 deletions(-) (limited to 'include/linux/hrtimer.h') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 6d93dce61cb..bdd88df1b4e 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -67,9 +67,10 @@ enum hrtimer_cb_mode { * 0x02 callback function running * 0x04 callback pending (high resolution mode) * - * Special case: + * Special cases: * 0x03 callback function running and enqueued * (was requeued on another CPU) + * 0x09 timer was migrated on CPU hotunplug * The "callback function running and enqueued" status is only possible on * SMP. It happens for example when a posix timer expired and the callback * queued a signal. Between dropping the lock which protects the posix timer @@ -87,6 +88,7 @@ enum hrtimer_cb_mode { #define HRTIMER_STATE_ENQUEUED 0x01 #define HRTIMER_STATE_CALLBACK 0x02 #define HRTIMER_STATE_PENDING 0x04 +#define HRTIMER_STATE_MIGRATE 0x08 /** * struct hrtimer - the basic hrtimer structure diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index ac2f6d6d486..ace723dd1e5 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1602,7 +1602,13 @@ static int migrate_hrtimer_list(struct hrtimer_clock_base *old_base, timer = rb_entry(node, struct hrtimer, node); BUG_ON(hrtimer_callback_running(timer)); debug_hrtimer_deactivate(timer); - __remove_hrtimer(timer, old_base, HRTIMER_STATE_INACTIVE, 0); + + /* + * Mark it as STATE_MIGRATE not INACTIVE otherwise the + * timer could be seen as !active and just vanish away + * under us on another CPU + */ + __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0); timer->base = new_base; /* * Enqueue the timer. Allow reprogramming of the event device @@ -1620,13 +1626,15 @@ static int migrate_hrtimer_list(struct hrtimer_clock_base *old_base, * state, we need to do that otherwise we end up with * a stale timer. */ - if (timer->state == HRTIMER_STATE_INACTIVE) { + if (timer->state == HRTIMER_STATE_MIGRATE) { timer->state = HRTIMER_STATE_PENDING; list_add_tail(&timer->cb_entry, &new_base->cpu_base->cb_pending); raise = 1; } #endif + /* Clear the migration state bit */ + timer->state &= ~HRTIMER_STATE_MIGRATE; } return raise; } -- cgit v1.2.3-70-g09d2 From ccc7dadf736639da86f3e0c86832c11a66fc8221 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 29 Sep 2008 15:47:42 +0200 Subject: hrtimer: prevent migration of per CPU hrtimers Impact: per CPU hrtimers can be migrated from a dead CPU The hrtimer code has no knowledge about per CPU timers, but we need to prevent the migration of such timers and warn when such a timer is active at migration time. Explicitely mark the timers as per CPU and use a more understandable mode descriptor for the interrupts safe unlocked callback mode, which is used by hrtimer_sleeper and the scheduler code. Signed-off-by: Thomas Gleixner --- include/linux/hrtimer.h | 14 +++++++++++--- kernel/hrtimer.c | 37 +++++++++++++++++++++++++------------ kernel/sched.c | 4 ++-- kernel/time/tick-sched.c | 2 +- kernel/trace/trace_sysprof.c | 2 +- 5 files changed, 40 insertions(+), 19 deletions(-) (limited to 'include/linux/hrtimer.h') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index bdd88df1b4e..2f245fe63bd 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -47,14 +47,22 @@ enum hrtimer_restart { * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and * does not restart the timer - * HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in hardirq context - * Special mode for tick emultation + * HRTIMER_CB_IRQSAFE_PERCPU: Callback must run in hardirq context + * Special mode for tick emulation and + * scheduler timer. Such timers are per + * cpu and not allowed to be migrated on + * cpu unplug. + * HRTIMER_CB_IRQSAFE_UNLOCKED: Callback should run in hardirq context + * with timer->base lock unlocked + * used for timers which call wakeup to + * avoid lock order problems with rq->lock */ enum hrtimer_cb_mode { HRTIMER_CB_SOFTIRQ, HRTIMER_CB_IRQSAFE, HRTIMER_CB_IRQSAFE_NO_RESTART, - HRTIMER_CB_IRQSAFE_NO_SOFTIRQ, + HRTIMER_CB_IRQSAFE_PERCPU, + HRTIMER_CB_IRQSAFE_UNLOCKED, }; /* diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index ace723dd1e5..cdec83e722f 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -672,13 +672,14 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, */ BUG_ON(timer->function(timer) != HRTIMER_NORESTART); return 1; - case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: + case HRTIMER_CB_IRQSAFE_PERCPU: + case HRTIMER_CB_IRQSAFE_UNLOCKED: /* * This is solely for the sched tick emulation with * dynamic tick support to ensure that we do not * restart the tick right on the edge and end up with * the tick timer in the softirq ! The calling site - * takes care of this. + * takes care of this. Also used for hrtimer sleeper ! */ debug_hrtimer_deactivate(timer); return 1; @@ -1245,7 +1246,8 @@ static void __run_hrtimer(struct hrtimer *timer) timer_stats_account_hrtimer(timer); fn = timer->function; - if (timer->cb_mode == HRTIMER_CB_IRQSAFE_NO_SOFTIRQ) { + if (timer->cb_mode == HRTIMER_CB_IRQSAFE_PERCPU || + timer->cb_mode == HRTIMER_CB_IRQSAFE_UNLOCKED) { /* * Used for scheduler timers, avoid lock inversion with * rq->lock and tasklist_lock. @@ -1452,7 +1454,7 @@ void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task) sl->timer.function = hrtimer_wakeup; sl->task = task; #ifdef CONFIG_HIGH_RES_TIMERS - sl->timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; + sl->timer.cb_mode = HRTIMER_CB_IRQSAFE_UNLOCKED; #endif } @@ -1592,7 +1594,7 @@ static void __cpuinit init_hrtimers_cpu(int cpu) #ifdef CONFIG_HOTPLUG_CPU static int migrate_hrtimer_list(struct hrtimer_clock_base *old_base, - struct hrtimer_clock_base *new_base) + struct hrtimer_clock_base *new_base, int dcpu) { struct hrtimer *timer; struct rb_node *node; @@ -1603,6 +1605,18 @@ static int migrate_hrtimer_list(struct hrtimer_clock_base *old_base, BUG_ON(hrtimer_callback_running(timer)); debug_hrtimer_deactivate(timer); + /* + * Should not happen. Per CPU timers should be + * canceled _before_ the migration code is called + */ + if (timer->cb_mode == HRTIMER_CB_IRQSAFE_PERCPU) { + __remove_hrtimer(timer, old_base, + HRTIMER_STATE_INACTIVE, 0); + WARN(1, "hrtimer (%p %p)active but cpu %d dead\n", + timer, timer->function, dcpu); + continue; + } + /* * Mark it as STATE_MIGRATE not INACTIVE otherwise the * timer could be seen as !active and just vanish away @@ -1619,12 +1633,11 @@ static int migrate_hrtimer_list(struct hrtimer_clock_base *old_base, /* * Happens with high res enabled when the timer was * already expired and the callback mode is - * HRTIMER_CB_IRQSAFE_NO_SOFTIRQ - * (hrtimer_sleeper). The enqueue code does not move - * them to the soft irq pending list for - * performance/latency reasons, but in the migration - * state, we need to do that otherwise we end up with - * a stale timer. + * HRTIMER_CB_IRQSAFE_UNLOCKED (hrtimer_sleeper). The + * enqueue code does not move them to the soft irq + * pending list for performance/latency reasons, but + * in the migration state, we need to do that + * otherwise we end up with a stale timer. */ if (timer->state == HRTIMER_STATE_MIGRATE) { timer->state = HRTIMER_STATE_PENDING; @@ -1682,7 +1695,7 @@ static void migrate_hrtimers(int cpu) for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { if (migrate_hrtimer_list(&old_base->clock_base[i], - &new_base->clock_base[i])) + &new_base->clock_base[i], cpu)) raise = 1; } diff --git a/kernel/sched.c b/kernel/sched.c index 13dd2db9fb2..ad1962dc0aa 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -201,7 +201,7 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime) hrtimer_init(&rt_b->rt_period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); rt_b->rt_period_timer.function = sched_rt_period_timer; - rt_b->rt_period_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; + rt_b->rt_period_timer.cb_mode = HRTIMER_CB_IRQSAFE_UNLOCKED; } static void start_rt_bandwidth(struct rt_bandwidth *rt_b) @@ -1119,7 +1119,7 @@ static void init_rq_hrtick(struct rq *rq) hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); rq->hrtick_timer.function = hrtick; - rq->hrtick_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; + rq->hrtick_timer.cb_mode = HRTIMER_CB_IRQSAFE_PERCPU; } #else static inline void hrtick_clear(struct rq *rq) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 39019b3f762..cb02324bdb8 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -625,7 +625,7 @@ void tick_setup_sched_timer(void) */ hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); ts->sched_timer.function = tick_sched_timer; - ts->sched_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; + ts->sched_timer.cb_mode = HRTIMER_CB_IRQSAFE_PERCPU; /* Get the next period (per cpu) */ ts->sched_timer.expires = tick_init_jiffy_update(); diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c index bb948e52ce2..db58fb66a13 100644 --- a/kernel/trace/trace_sysprof.c +++ b/kernel/trace/trace_sysprof.c @@ -202,7 +202,7 @@ static void start_stack_timer(int cpu) hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hrtimer->function = stack_trace_timer_fn; - hrtimer->cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; + hrtimer->cb_mode = HRTIMER_CB_IRQSAFE_PERCPU; hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL); } -- cgit v1.2.3-70-g09d2