On Mon, Jun 21, 2021 at 02:04:30PM +0000, Visa Hankala wrote: > On Thu, May 27, 2021 at 07:40:26PM -0500, Scott Cheloha wrote: > > On Sun, May 23, 2021 at 09:05:24AM +0000, Visa Hankala wrote: > > > When a CPU starts processing a soft interrupt, it reserves the handler > > > to prevent concurrent execution. If the soft interrupt gets rescheduled > > > during processing, the handler is run again by the same CPU. This breaks > > > FIFO ordering, though. > > > > If you want to preserve FIFO you can reinsert the handler at the queue > > tail. That would be more fair. > > > > If FIFO is the current behavior I think we ought to keep it. > > I have updated the patch to preserve the FIFO order. > > > > +STAILQ_HEAD(x86_soft_intr_queue, x86_soft_intrhand); > > > + > > > +struct x86_soft_intr_queue softintr_queue[X86_NSOFTINTR]; > > > > Why did we switch to STAILQ? I know we don't have very many > > softintr_disestablish() calls but isn't O(1) removal worth the extra > > pointer? > > I used STAILQ because it avoids the hassle of updating the list nodes' > back pointers. softintr_disestablish() with multiple items pending in > the queue is very rare in comparison to the normal softintr_schedule() / > softintr_dispatch() cycle. > > However, I have changed the code back to using TAILQ.
This looks good to me. I mean, it looked good before, but it still looks good. I will run with it for a few days. Assuming I hit no issues I'll come back with an OK. Is there an easy way to exercise this code from userspace? There aren't many softintr users. Maybe audio drivers?
