Re: questions on wait_event ...

[Alexey Shinkin]

Look:

We call wait_event() , condition is FALSE at the moment  :

   do {
        if (condition)
                break;
   /* and here we have condition changed  to TRUE  */
   /*  process is NOT in any wait queue yet  */
   /*  then  unroll     __wait_event(wq, condition);        */

    do {							DEFINE_WAIT(__wait);					for (;;) {
	prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);

         /* at this point condition is TRUE , process is in a wait queue 
and its state is
            TASK_UNINTERRUPTIBLE.   If  rescheduling happens now the 
process will asleep,
             despite of condition is  TRUE . And will not be woken up until 
next wake_up happens
             Is that correct ?  */

	if (condition)						     break;
                   schedule();
       }
  finish_wait(&wq, &__wait);
} while (0)
  /*  end of unroll __wait_event*/

} while (0)

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/