2023-06-06 14:43:29

by Thomas Gleixner

Subject: [patch 17/45] posix-cpu-timers: Make k_itimer::it_active consistent

Posix CPU timers are not updating k_itimer::it_active which makes it
impossible to base decisions in the common posix timer code on it.

Update it when queueing or dequeueing posix CPU timers.

Signed-off-by: Thomas Gleixner <[email protected]>
---
kernel/time/posix-cpu-timers.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -453,6 +453,7 @@ static void disarm_timer(struct k_itimer
struct cpu_timer *ctmr = &timer->it.cpu;
struct posix_cputimer_base *base;

+ timer->it_active = 0;
if (!cpu_timer_dequeue(ctmr))
return;

@@ -559,6 +560,7 @@ static void arm_timer(struct k_itimer *t
struct cpu_timer *ctmr = &timer->it.cpu;
u64 newexp = cpu_timer_getexpires(ctmr);

+ timer->it_active = 1;
if (!cpu_timer_enqueue(&base->tqhead, ctmr))
return;

@@ -668,6 +670,7 @@ static int posix_cpu_timer_set(struct k_
ret = TIMER_RETRY;
} else {
cpu_timer_dequeue(ctmr);
+ timer->it_active = 0;
}

/*
@@ -787,6 +790,7 @@ static u64 collect_timerqueue(struct tim

while ((next = timerqueue_getnext(head))) {
struct cpu_timer *ctmr;
+ struct k_itimer *ktmr;
u64 expires;

ctmr = container_of(next, struct cpu_timer, node);
@@ -799,6 +803,8 @@ static u64 collect_timerqueue(struct tim
/* See posix_cpu_timer_wait_running() */
rcu_assign_pointer(ctmr->handling, current);
cpu_timer_dequeue(ctmr);
+ ktmr = container_of(ctmr, struct k_itimer, it.cpu);
+ ktmr->it_active = 0;
list_add_tail(&ctmr->elist, firing);
}

2023-07-03 22:49:42

by Frederic Weisbecker

Subject: Re: [patch 17/45] posix-cpu-timers: Make k_itimer::it_active consistent

On Tue, Jun 06, 2023 at 04:37:45PM +0200, Thomas Gleixner wrote:
> @@ -787,6 +790,7 @@ static u64 collect_timerqueue(struct tim
>
> while ((next = timerqueue_getnext(head))) {
> struct cpu_timer *ctmr;
> + struct k_itimer *ktmr;
> u64 expires;
>
> ctmr = container_of(next, struct cpu_timer, node);
> @@ -799,6 +803,8 @@ static u64 collect_timerqueue(struct tim
> /* See posix_cpu_timer_wait_running() */
> rcu_assign_pointer(ctmr->handling, current);
> cpu_timer_dequeue(ctmr);
> + ktmr = container_of(ctmr, struct k_itimer, it.cpu);
> + ktmr->it_active = 0;

Maybe move this to cpu_timer_fire() because:

1) Other posix-timer implementation set it_active = 0
from their actual handler.

2) This place doesn't have the timer locked. Better Make
sure we have this protection to avoid mistakes against
potential future use of it_active.

Thanks.

> list_add_tail(&ctmr->elist, firing);
> }
>
>