Ben, On Mon, 19 Aug 2019, luoben wrote: > 在 2019/8/15 下午10:58, Thomas Gleixner 写道: > > > This narrows the gap for setting up new irq (and irte, if has) > > What does that mean: "narrows the gap" > > > > What's the gap and why is it only made smaller and not closed? > > Sorry for confusing. The so called 'gap' is a time window between free_irq() > and request_irq().
And exactly this information wants to be in the changelog. > > function please. Also it does not matter whether the time is short or > > not. The point is: > > > > Ensure that an interrupt in flight on another CPU which uses > > the > > old 'dev_id' has completed because the caller can free the > > memory > > to which it points after this function returns. > > > > But this has another twist: > > > > CPU0 CPU1 > > > > interrupt > > primary_handler(old_dev_id) > > do_stuff_on(old_dev_id) > > return WAKE_THREAD; update_dev_id() > > wakeup_thread(); > > action->dev_id = new_dev_id; > > irq_thread() > > secondary_handler(new_dev_id) > > > > That's broken and synchronize_irq() does not protect against it. > > Thanks to point it out, I will change to the following in next version, is > that ok? > > ... > > /* ^^^ Please use a mail client which does not insert random wierd characters. > * Ensure that an interrupt in flight on another CPU which uses the > * old 'dev_id' has completed because the caller can free the memory > * to which it points after this function returns. And also void to s/void/avoid/ > * update 'dev_id' in the middle of a threaded interrupt process, it > * can lead to a twist that primary handler uses old 'dev_id' but new > * 'dev_id' is used by secondary handler. > */ > disable_irq(irq); Yes, that works. Thanks, tglx