On Mon, Oct 12, 2020 at 09:50:44PM +0800, Pingfan Liu wrote: > __do_softirq() may be interrupted by hardware interrupts. In this case, > irqtime_account_irq() will account the time slice as CPUTIME_SOFTIRQ by > mistake. > > By passing irqtime_account_irq() an extra param about either hardirq or > softirq, irqtime_account_irq() can handle the above case.
I'm not sure I see the scenario in which it goes wrong. irqtime_account_irq() is designed such that we're called with the old preempt_count on enter and the new preempt_count on exit. This way we'll accumuate the delta to the previous context. > @@ -68,7 +68,7 @@ void irqtime_account_irq(struct task_struct *curr) > */ > if (hardirq_count()) > irqtime_account_delta(irqtime, delta, CPUTIME_IRQ); > - else if (in_serving_softirq() && curr != this_cpu_ksoftirqd()) > + else if (in_serving_softirq() && curr != this_cpu_ksoftirqd() && > !hardirq) > irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ); > }