lkml.org 
[lkml]   [2009]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [patch 1/3] net: serialize hrtimer callback in sched_cbq
From
Date
On Tue, 2009-07-14 at 09:42 -0700, Linus Torvalds wrote:
>
> On Tue, 14 Jul 2009, Peter Zijlstra wrote:
> >
> > Linus really hated the softirq mode, which is what prompted me to change
> > that.
> >
> > Now, it might be he only hated the particular interface and the
> > resulting code, but I think to remember he simply thought the whole
> > thing daft.
>
> Yes. And I hated the bugs it had.
>
> Don't make something as core as timers any more complicated. Don't take
> locks in timers and then complain about deadlocks. If your locking is
> broken, don't make the core timers be idiotically broken.
>
> Because it was. The code was a total mess to follow, and had bugs.

How would something like the below work for people?

---
include/linux/hrtimer.h | 22 ++++++++++++++++++++--
kernel/hrtimer.c | 23 ++++++++++++++++++++++-
2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 4759917..e7559fe 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -22,6 +22,7 @@
#include <linux/wait.h>
#include <linux/percpu.h>
#include <linux/timer.h>
+#include <linux/interrupt.h>


struct hrtimer_clock_base;
@@ -91,7 +92,6 @@ enum hrtimer_restart {
* @function: timer expiry callback function
* @base: pointer to the timer base (per cpu and per clock)
* @state: state information (See bit values above)
- * @cb_entry: list head to enqueue an expired timer into the callback list
* @start_site: timer statistics field to store the site where the timer
* was started
* @start_comm: timer statistics field to store the name of the process which
@@ -108,7 +108,6 @@ struct hrtimer {
enum hrtimer_restart (*function)(struct hrtimer *);
struct hrtimer_clock_base *base;
unsigned long state;
- struct list_head cb_entry;
#ifdef CONFIG_TIMER_STATS
int start_pid;
void *start_site;
@@ -116,6 +115,12 @@ struct hrtimer {
#endif
};

+struct hrtimer_softirq {
+ struct hrtimer timer;
+ struct tasklet_struct tasklet;
+ enum hrtimer_restart (*function)(struct hrtimer *);
+};
+
/**
* struct hrtimer_sleeper - simple sleeper structure
* @timer: embedded timer structure
@@ -335,6 +340,19 @@ static inline void hrtimer_init_on_stack(struct hrtimer *timer,
static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
#endif

+enum hrtimer_restart __hrtimer_softirq_trampoline(struct hrtimer *timer);
+void __hrtimer_tasklet_trampoline(unsigned long data);
+
+static inline void hrtimer_softirq_init(struct hrtimer_softirq *stimer,
+ enum hrtimer_restart (*func)(struct hrtimer *),
+ clockid_t which_clock, enum hrtimer_mode mode)
+{
+ hrtimer_init(&stimer->timer, which_clock, mode);
+ stimer->timer.function = __hrtimer_softirq_trampoline;
+ tasklet_init(&stimer->tasklet, __hrtimer_tasklet_trampoline, stimer);
+ stimer->function = func;
+}
+
/* Basic timer operations: */
extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
const enum hrtimer_mode mode);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ab5eb70..dae063c 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1098,7 +1098,6 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
clock_id = CLOCK_MONOTONIC;

timer->base = &cpu_base->clock_base[clock_id];
- INIT_LIST_HEAD(&timer->cb_entry);
hrtimer_init_timer_hres(timer);

#ifdef CONFIG_TIMER_STATS
@@ -1141,6 +1140,28 @@ int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
}
EXPORT_SYMBOL_GPL(hrtimer_get_res);

+enum hrtimer_restart __hrtimer_softirq_trampoline(struct hrtimer *timer)
+{
+ struct hrtimer_softirq *stimer =
+ container_of(timer, struct hrtimer_softirq, timer);
+
+ tasklet_hi_schedule(&timer->tasklet);
+
+ return HRTIMER_NORESTART;
+}
+EXPORT_SYMBOL_GPL(__hrtimer_softirq_trampoline);
+
+void __hrtimer_tasklet_trampoline(unsigned long data)
+{
+ struct hrtimer_softirq *stimer = (void *)data;
+ enum hrtimer_restart restart;
+
+ restart = stimer->function(&stimer->timer);
+ if (restart != HRTIMER_NORESTART)
+ hrtimer_restart(&stimer->timer);
+}
+EXPORT_SYMBOL_GPL(__hrtimer_tasklet_trampoline);
+
static void __run_hrtimer(struct hrtimer *timer)
{
struct hrtimer_clock_base *base = timer->base;


\
 
 \ /
  Last update: 2009-07-17 14:17    [W:0.062 / U:56.376 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site