On Sun, 07 Jun 2015, Nicholas Mc Guire wrote:
Hi !
Noticed that in a number of cases - often while(!kthread_should_stop()){ loops the call to set_current_state(...) is inside the loop - but e.g. in the below case why would that be needed ? schedule() is not changing the state visibly for the loop - so what is the point of setting the state inside the loop ?
e.g. net/core/pktgen.c /* Wait for kthread_stop */ while (!kthread_should_stop()) { set_current_state(TASK_INTERRUPTIBLE); schedule(); }
from code review it seems to be that this would be equivalent
set_current_state(TASK_INTERRUPTIBLE); while (!kthread_should_stop()) { schedule(); }
what did I miss ?
rereading __schedule() - state after schedule() is always TASK_RUNNING - so setting it back to !=TASK_RUNNING would be needed in the loop - but in the above case I still don't get the point of flipping the task state between TASK_INTERRUPTIBLE and TASK_RUNNING the set_current_state(TASK_INTERRUPTIBLE); seems to have no real effect as at the end of the loop state is TASK_RUNNING in any case and ntermediately it is in TASK_RUNNING state as well ? so I still seem to be missing something here... thx! hofrat