Hi,
I had a closer look to the tasklet implementation, especially
to tasklet_kill. I do not understand, why at the end of
the function the TASKLET_STATE_SCHED bit is cleared. Is it
a bug or a feature? Maybe someone can help me.
The function tasklet_schedule does two things:
1. it sets the schedule_bit (TASKLET_STATE_SCHED)
2. if the bit wasn't set (cleared) it puts the tasklet on the
tasklet_vec list.
By the trick, to set the schedule_bit without putting
the tasklet on the list, a tasklet can be "killed"
(it is not on the list and tasklet_schedule is not going
to put it on the list). But in the current implementation
of tasklet_kill the schedule_bit is cleared (last line of
the function)? In this case the next tasklet_schedule
"works" and the tasklet-function will be called again.
So, is it a bug? What do we achieve by clearing the
schedule_bit? Can we remove the "clear_bit" line
(it is not necessary to call "set_bit", because
"test_and_set_bit" has set it before)?
Or what is _exactly_ the purpose of tasklet_kill?
Juergen.
=====================
void tasklet_kill(struct tasklet_struct *t)
{
if (in_interrupt())
printk("Attempt to kill tasklet from interrupt\n");
while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
do
yield();
while (test_bit(TASKLET_STATE_SCHED, &t->state));
}
tasklet_unlock_wait(t);
clear_bit(TASKLET_STATE_SCHED, &t->state);
}
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This archive was generated by hypermail 2b29 : Sun Dec 15 2002 - 22:00:31 EST