* tasklet_kill makes sure no future re-schedule?
@ 2016-07-28 19:52 Wengang
0 siblings, 0 replies; only message in thread
From: Wengang @ 2016-07-28 19:52 UTC (permalink / raw)
To: linux-kernel; +Cc: Wengang Wang, Santosh Shilimkar, Srinivas Eeda
Hi,
I recently hit an issue that after tasklet_kill called against a tasket,
the tasklet can still be scheduled in IRQ context and run at a later time.
So my question is whether tasklet_kill is designed to make sure no
future re-scheduling can be done. I didn't find an official document
stating that, but find some non-official ones. The thing is that the
voices are different:
Someone (http://www.makelinux.net/books/lkd2/ch07lev1sec3) says
"You can remove a tasklet from the pending queue via tasklet_kill().
This function receives a pointer as a lone argument to the tasklet's
tasklet_struct. Removing a scheduled tasklet from the queue is useful
when dealing with a tasklet that often reschedules itself. This function
first waits for the tasklet to finish executing and then it removes the
tasklet from the queue. Nothing stops some other code from rescheduling
the tasklet, of course. This function must not be used from interrupt
context because it sleeps."
And someone else (http://www.makelinux.net/ldd3/chp-7-sect-5) says
"This function ensures that the tasklet is not scheduled to run again;
it is usually called when a device is being closed or the module
removed. If the tasklet is scheduled to run, the function waits until it
has executed. If the tasklet reschedules itself, you must prevent it
from rescheduling itself before calling tasklet_kill, as with
del_timer_sync."
Looking at the code, I prefer "Nothing stops some other code from
rescheduling the lasklet". But I want a confirm here please!
Thanks,
Wengang
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