On Tuesday, 30 January 2007 23:32, Rafael J. Wysocki wrote: > [Added linux-pm to the Cc list, because I'm going to talk about things that > I know only from reading the code.] > > On Tuesday, 30 January 2007 17:50, Oliver Neukum wrote: > > Am Dienstag, 30. Januar 2007 17:32 schrieb Rafael J. Wysocki: > > > However, you can always inspect the PF_FROZEN flag of the tasks in question > > > if that's practicable. > > > > What would I do with that information? Ignore completion of IO? > > I probably should say "that depends", but that wouldn't be very helpful. > > Getting back to your initial question, which is if wake_up() may be called > from a driver's .resume() routine, I think the answer is no, it may not, > because in that case the "notified" tasks would be removed from the wait > queue, but the refrigerator() would (wrongly) restore their states as > TASK_UNINTERRUPTIBLE (or TASK_INTERRUPTIBLE for wake_up_interruptible()). > > Generally, you are safe if your driver only calls wake_up() from a process > context, but not from .resume() or .suspend() routines (or from an > unfreezeable kernel thread). Ah, sorry, I've just realized I was wrong. Processes in TASK_UNINTERRUPTIBLE cannot be frozen! So, the above only applies to wake_up_interruptible(). You don't need to call wake_up() from .resume(), because there are no tasks to be notified this way and you shouldn't call wake_up_interruptible() from there. Greetings, Rafael -- If you don't have the time to read, you don't have the time or the tools to write. - Stephen King
