Date: Wed, 20 Sep 1995 16:58:44 -0500 (CDT) From: Mike Pritchard <mpp@mpp.minn.net> To: terry@lambert.org (Terry Lambert) Cc: terry@lambert.org, nate@rocky.sri.MT.net, davidg@root.com, hackers@freefall.freebsd.org Subject: Re: Coding style ( was Re: why is this not a bug in namei?) Message-ID: <199509202158.QAA12896@mpp.minn.net> In-Reply-To: <199509201711.KAA01075@phaeton.artisoft.com> from "Terry Lambert" at Sep 20, 95 10:11:52 am
next in thread | previous in thread | raw e-mail | index | archive | help
Terry Lambert wrote:
>
> Why not:
>
> XXX_LOCK();
> ...
> if (error_condition) {
> error = EWHATEVER;
> goto err_with_lock_held;
> }
> ...
> err_with_lock_held:
> XXX_UNLOCK():
> err:
> return (error);
>
> Or better yet:
>
> XXX_LOCK();
> ...
> if (error_condition) {
> error = EWHATEVER;
> } else {
> ...
> }
> XXX_UNLOCK():
> err:
> return (error);
>
> I don't understand the need for the local lock state variable in your
> second example.
My previous example was very simplistic. Having to lock multiple objects
during a function wasn't not uncommon.
E.g.
XXX_LOCK();
...
if (error_condition) {
XXX_UNLOCK();
return (EWHATEVER);
}
...
XXX_UNLOCK();
...
if (error_condition2)
return (EHWATEVER);
...
YYY_LOCK();
...
if (error_condition2) {
YYY_UNLOCK();
return (EWHATEVER);
}
...
YYY_UNLOCK();
return (0);
In the above example, with gotos you would need 4 exit points: 1 for
an exit without any error. And one each for each of the 3 error
conditions, since they all have different requirements. 2 of them have
different locks, and 1 has no locks at all.
--
Mike Pritchard
mpp@mpp.minn.net
"Go that way. Really fast. If something gets in your way, turn"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199509202158.QAA12896>