Re: [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation

[Peter Zijlstra]

On Wed, Dec 02, 2020 at 12:57:31PM +0100, Frederic Weisbecker wrote:
> IRQ time entry is currently accounted before HARDIRQ_OFFSET or
> SOFTIRQ_OFFSET are incremented. This is convenient to decide to which
> index the cputime to account is dispatched.
> 
> Unfortunately it prevents tick_irq_enter() from being called under
> HARDIRQ_OFFSET because tick_irq_enter() has to be called before the IRQ
> entry accounting due to the necessary clock catch up. As a result we
> don't benefit from appropriate lockdep coverage on tick_irq_enter().
> 
> To prepare for fixing this, move the IRQ entry cputime accounting after
> the preempt offset is incremented. This requires the cputime dispatch
> code to handle the extra offset.
> 
> Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>