Commit 9ba5f005 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

softirq: introduce tasklet_hrtimer infrastructure

commit ca109491

 (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: default avatarPeter Zijlstra <>
Cc: David Miller <>
LKML-Reference: <1248265724.27058.1366.camel@twins>
Signed-off-by: default avatarThomas Gleixner <>
parent aea1f796
......@@ -14,6 +14,7 @@
#include <linux/irqflags.h>
#include <linux/smp.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
#include <asm/atomic.h>
#include <asm/ptrace.h>
......@@ -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)
* Autoprobing for irqs:
......@@ -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)
* 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)) {
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)
* 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;
* Remote softirq bits
DEFINE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);
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