Damn. I should reread my mail before sending them.
Manfred Spraul wrote:
> > do_pollfd() calls the driver poll routine. Is it
> > expected that the driver might in some way call schedule() and put the
> > current task to sleep?
>
> Yes.
This one is wrong.
do_pollfd calls f_ops->poll() [yes to the first part], but the driver
should not call schedule() [no to the second part], it should avoid it
whereever possible. It might happen that it sleeps, but the
TASK_INTERRUPTIBLE has nothing to do with that sleeping.
TASK_INTERRUPTIBLE is required for the Linux wait queue implementation,
as explained in Alan's mouse driver article.
If the driver must sleep, then someone must reset current->state to
TASK_RUNNING before sleeping: a driver calls
poll_wait()->__pollwait()->kmalloc()->...->try_to_free_pages()
and try_to_free_pages will resets current->state.
Sorry for the confusion,
Manfred
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This archive was generated by hypermail 2b29 : Sun Jul 23 2000 - 21:00:09 EST