Re: [PATCH RFC bpf-next v3 04/16] bpf/helpers: introduce sleepable bpf_timers

On Wed, 2024-02-21 at 17:25 +0100, Benjamin Tissoires wrote:

[...]

@@ -1282,7 +1333,7 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla if (in_nmi()) return -EOPNOTSUPP;

• if (flags & ~(BPF_F_TIMER_ABS | BPF_F_TIMER_CPU_PIN))

• if (flags & ~(BPF_F_TIMER_ABS | BPF_F_TIMER_CPU_PIN | BPF_F_TIMER_SLEEPABLE)) return -EINVAL; __bpf_spin_lock_irqsave(&timer->lock); t = timer->timer;

@@ -1299,7 +1350,10 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla if (flags & BPF_F_TIMER_CPU_PIN) mode |= HRTIMER_MODE_PINNED;

• hrtimer_start(&t->timer, ns_to_ktime(nsecs), mode);

• if (flags & BPF_F_TIMER_SLEEPABLE)

• schedule_work(&t->work);
  

• else

• hrtimer_start(&t->timer, ns_to_ktime(nsecs), mode);
  

It looks like nsecs is simply ignored for sleepable timers. Should this be hrtimer_start() that waits nsecs and schedules work, or schedule_delayed_work()? (but it takes delay in jiffies, which is probably too coarse). Sorry if I miss something.