Lots of bugs with current->state = TASK_*INTERRUPTIBLE

Steven Rostedt
2010-01-19T20:29:38Z

Peter Zijlstra and I were doing a look over of places that assign
current->state = TASK_*INTERRUPTIBLE, by simply looking at places with:

$ git grep -A1 'state[[:space:]]*=[[:space:]]*TASK_[^R]'

and it seems there are quite a few places that looks like bugs. To be on
the safe side, everything outside of a run queue lock that sets the
current state to something other than TASK_RUNNING (or dead) should be
using set_current_state().

current->state = TASK_INTERRUPTIBLE;
schedule();

is probably OK, but it would not hurt to be consistent. Here's a few
examples of likely bugs:

From drivers/staging/line6/midi.c:

current->state = TASK_INTERRUPTIBLE;

while (line6->line6midi->num_active_send_urbs > 0)

From drivers/staging/line6/pod.c:

current->state = TASK_INTERRUPTIBLE;

while (param->value = POD_system_invalid) {

Also drivers/macintosh/adb.c looks like there's a bug too.

I'm sure there's others but I stopped looking.

Anyway, this looks like a good janitorial work. Anything that assigns
state outside the rq locks to something other than TASK_RUNNING and that
is not before a schedule() (perhaps even those) should be converted to:

set_current_task(<state>).

This probably should be checked in checkpatch.pl too, if it is not
already.

-- Steve