Messages in this thread | | | Date | Sat, 14 Dec 2002 21:16:37 +0100 | From | Juergen Quade <> | Subject | tasklet_kill: bug or feature? |
| |
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); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |