-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Wednesday, March 11, 2015 10:00 AM
To: Nicholas Mc Guire
Cc: Bj??rn Mork; [email protected]
Subject: Re: confusing code....whats the point of this construct ?
On Wed, 11 Mar 2015 17:46:56 +0100, Nicholas Mc Guire said:
> ret = ({ long __ret = (5*250);
> do { _cond_resched(); } while (0);
> if (!({
> bool __cond = (({
>Gaak.
>
> ret = wait_event_timeout(mgr->tx_waitq,
> check_txmsg_state(mgr, txmsg),
> (4 * HZ));
>-EGADS - use of macro as a function violates the Principle of Least
>Surprise....
>
>I have to wonder how many other places we've got bugs waiting to happen
>because of this....
I don't understand the problem here. The caller passes in a condition to be
evaluated in a loop. Many times that condition is quite simple (e.g. a counter
being non-zero). If it was a function the caller would have to pass in a
pointer to a function that does the evaluation, as in:
int bar;
int foo(void)
{
return bar;
}
...
wait_event_interruptible(..., foo, ...);
Instead of the much simpler:
wait_event_interruptible(..., bar, ...);
That latter seems easier to understand and require fewer instructions to be
generated since there is no function call overhead.
Jeff Haran
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