On Tue, 19 Dec 2017 16:33:10 +0100 Sebastian Andrzej Siewior <[email protected]> wrote:
> On 2017-12-19 10:28:39 [-0500], Steven Rostedt wrote: > > On Tue, 19 Dec 2017 16:04:18 +0100 > > Sebastian Andrzej Siewior <[email protected]> wrote: > > > > > > > > > > The above just seems wrong. local_irq_disable() should imply > > > > local_bh_disable(), as it doesn't let softirqs run either. > > > > > > Where does local_irq_disable() imply this? > > > > If it doesn't explicitly do so, it probably should. How can we have a > > softirq execute when irqs are disabled? > > There are not. With local_bh_disable() the softirq will run on > local_bh_enable(). Without it (and with or without local_irq_disable()) > the softirq won't run but wakeup the ksoftirq thread. We can't do the > wake while holding the hrtimer lock. This is not RT specific. > Then there should be a comment there, as it is way too subtle. As local_bh_disable() is usually used only to prevent softirq from running on the current CPU during a critical period. Where, here we are using it to avoid a wake up of ksoftirqd. -- Steve
