On Fri, 2010-05-28 at 01:44 +1000, Nick Piggin wrote: > > if (supers_dirty) > > bdi_arm_supers_timer(); > > set_current_state(TASK_INTERRUPTIBLE); > > schedule(); > But we cannot do the above, because again the timer might go off > before we set current state. We'd lose the wakeup and never wake > up again. > > Putting it inside set_current_state() should be OK. I suppose. Hmm, but it looks like we cannot do that either. If we do set_current_state(TASK_INTERRUPTIBLE); if (supers_dirty) bdi_arm_supers_timer(); schedule(); and the kernel is preemptive, is it possible that we get preempted before we run 'bdi_arm_supers_timer()', but after we do 'set_current_state(TASK_INTERRUPTIBLE)'. And we will never wake up if the timer armed in mark_sb_dirty() went off. So it looks like this is the way to go: /* * Disable preemption for a while to make sure we are not * preempted before the timer is armed. */ preempt_disable(); set_current_state(TASK_INTERRUPTIBLE); if (supers_dirty) bdi_arm_supers_timer(); preempt_enable(); schedule(); -- Best Regards, Artem Bityutskiy (Артём Битюцкий) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
