> Is this analysis correct? If it is, perhaps there is an alternative
> to fixing these cases individually: make the TASK_INTERRUPTIBLE/
> TASK_UNINTERRUPTIBLE states block preemption. In which case the
> 'set_current_state(TASK_RUNNING)' macro would need to include the
> same preemption check as 'preemption_enable'.
Thankfully you are wrong or we would have some serious problems :)
See kernel/sched.c :: preempt_schedule() where we set p->preempt_count
to PREEMPT_ACTIVE.
Then see kernel/sched.c :: schedule() where we short-circuit the
remove-from-runqueue code if PREEMPT_ACTIVE is set.
Thus, it is safe to preempt regardless of the task's state. It will
eventually reschedule.
Robert Love
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