On (24/10/24 14:18), Tomasz Figa wrote: > > @@ -1538,9 +1538,25 @@ static int venc_close(struct file *file) > > > > venc_pm_get(inst); > > > > + /* > > + * First, remove the inst from the ->instances list, so that > > + * to_instance() will return NULL. > > + */ > > + hfi_session_destroy(inst); > > + /* > > + * Second, make sure we don't have IRQ/IRQ-thread currently running or > > + * pending execution (disable_irq() calls synchronize_irq()), which > > + * can race with the inst destruction. > > + */ > > + disable_irq(inst->core->irq); > > + /* > > + * Lastly, inst is gone from the core->instances list and we don't > > + * have running/pending IRQ/IRQ-thread, proceed with the destruction > > + */ > > + enable_irq(inst->core->irq); > > + > > Thanks a lot for looking into this. Wouldn't it be enough to just call > synchronize_irq() at this point, since the instance was removed from > the list already? I guess the question is if that's the only way the > interrupt handler can get hold of the instance. Good question. synchronize_irq() waits for IRQ-threads, so if inst is accessed only from IRQ-thread then we are fine. If, however, inst is also accessed from hard IRQ, then synchronize_irq() won't work, I guess, because it doesn't wait for "in flight hard IRQs". disable_irq() OTOH "waits for completion", so we cover in-flight hard IRQs too.
