On Wed, May 11, 2005 at 11:04:24PM -0400, Harry Orenstein wrote:
> Apparently, the function 'interruptible_sleep_on' is deprecated in favor of
> 'wait_event_interruptible', which requires an additional parameter (a
> condition on which to wait).
If you have old code something like
while(1) {
if(new_wombats(inode))
break;
/* POINT A */
interruptible_sleep_on(&wombat_factory);
}
this has problems if a wombat is produced at point A, you may sleep forever
unless you are using the old lock_kernel locking. With the new locking the
wait_event macros unroll the testing into the sleep so the result is safely
ordered and it becomes
wait_event_interruptible(wombat_factory, new_wombats(inode));
(One thing confusing about this is that it is a macro so new_wombats() isn't
called once and passed to the function, its called each time the kernel wants
to decide if we woke for the right reason).
This assumes new_wombats() returns 0 for "no" and 1 for "yes, finished".
In effect you write a function that tests if we should wake up and that is
the macro argument. You can also place simple tests in the call itself - eg
wait_event_interruptible(queue->wait, queue->tail != queue->head);
Alan
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