From 9ba5f005c994ad28e266a0cd14ef29354be382c9 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 22 Jul 2009 14:18:35 +0200 Subject: [PATCH] softirq: introduce tasklet_hrtimer infrastructure commit ca109491f (hrtimer: removing all ur callback modes) moved all hrtimer callbacks into hard interrupt context when high resolution timers are active. That breaks code which relied on the assumption that the callback happens in softirq context. Provide a generic infrastructure which combines tasklets and hrtimers together to provide an in-softirq hrtimer experience. Signed-off-by: Peter Zijlstra Cc: torvalds@linux-foundation.org Cc: kaber@trash.net Cc: David Miller LKML-Reference: <1248265724.27058.1366.camel@twins> Signed-off-by: Thomas Gleixner --- include/linux/interrupt.h | 26 ++++++++++++++++ kernel/softirq.c | 64 ++++++++++++++++++++++++++++++++++++++- 2 files changed, 89 insertions(+), 1 deletion(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 2721f07e9354..fd4c9c63c757 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -517,6 +518,31 @@ extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu); extern void tasklet_init(struct tasklet_struct *t, void (*func)(unsigned long), unsigned long data); +struct tasklet_hrtimer { + struct hrtimer timer; + struct tasklet_struct tasklet; + enum hrtimer_restart (*function)(struct hrtimer *); +}; + +extern void +tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, + enum hrtimer_restart (*function)(struct hrtimer *), + clockid_t which_clock, enum hrtimer_mode mode); + +static inline +int tasklet_hrtimer_start(struct tasklet_hrtimer *ttimer, ktime_t time, + const enum hrtimer_mode mode) +{ + return hrtimer_start(&ttimer->timer, time, mode); +} + +static inline +void tasklet_hrtimer_cancel(struct tasklet_hrtimer *ttimer) +{ + hrtimer_cancel(&ttimer->timer); + tasklet_kill(&ttimer->tasklet); +} + /* * Autoprobing for irqs: * diff --git a/kernel/softirq.c b/kernel/softirq.c index 3a94905fa5d2..eb5e131a0485 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -345,7 +345,9 @@ void open_softirq(int nr, void (*action)(struct softirq_action *)) softirq_vec[nr].action = action; } -/* Tasklets */ +/* + * Tasklets + */ struct tasklet_head { struct tasklet_struct *head; @@ -493,6 +495,66 @@ void tasklet_kill(struct tasklet_struct *t) EXPORT_SYMBOL(tasklet_kill); +/* + * tasklet_hrtimer + */ + +/* + * The trampoline is called when the hrtimer expires. If this is + * called from the hrtimer interrupt then we schedule the tasklet as + * the timer callback function expects to run in softirq context. If + * it's called in softirq context anyway (i.e. high resolution timers + * disabled) then the hrtimer callback is called right away. + */ +static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer) +{ + struct tasklet_hrtimer *ttimer = + container_of(timer, struct tasklet_hrtimer, timer); + + if (hrtimer_is_hres_active(timer)) { + tasklet_hi_schedule(&ttimer->tasklet); + return HRTIMER_NORESTART; + } + return ttimer->function(timer); +} + +/* + * Helper function which calls the hrtimer callback from + * tasklet/softirq context + */ +static void __tasklet_hrtimer_trampoline(unsigned long data) +{ + struct tasklet_hrtimer *ttimer = (void *)data; + enum hrtimer_restart restart; + + restart = ttimer->function(&ttimer->timer); + if (restart != HRTIMER_NORESTART) + hrtimer_restart(&ttimer->timer); +} + +/** + * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks + * @ttimer: tasklet_hrtimer which is initialized + * @function: hrtimer callback funtion which gets called from softirq context + * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME) + * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL) + */ +void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer, + enum hrtimer_restart (*function)(struct hrtimer *), + clockid_t which_clock, enum hrtimer_mode mode) +{ + hrtimer_init(&ttimer->timer, which_clock, mode); + ttimer->timer.function = __hrtimer_tasklet_trampoline; + tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline, + (unsigned long)ttimer); + ttimer->function = function; +} +EXPORT_SYMBOL_GPL(tasklet_hrtimer_init); + +/* + * Remote softirq bits + */ + DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list); EXPORT_PER_CPU_SYMBOL(softirq_work_list);