Messages in this thread | | | Date | Sun, 20 Mar 2005 14:18:04 +0100 (CET) | From | Jesper Juhl <> | Subject | Re: [PATCH] don't do pointless NULL checks and casts before kfree() in security/ |
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On Sun, 20 Mar 2005, Ralph Corderoy wrote:
> > Hi Jesper, > > > kfree() handles NULL pointers, so checking a pointer for NULL before > > calling kfree() on it is pointless. > > Not necessarily. It helps tell the reader that the pointer may be NULL > at that point. This has come up before. > > http://groups-beta.google.com/group/linux.kernel/browse_thread/thread/bd3d6e5a29e43c73/7b43819f874295e8?q=ralph@inputplus.co.uk+persuade+lkml#7b43819f874295e8 >
I agree that
if (foo->bar) { kfree(foo->bar); foo->bar = NULL; }
makes it easy to see that foo->bar might be NULL, but I think the advantages of simply
kfree(foo->bar); foo->bar = NULL;
outweigh that.
Having to remember that kfree(NULL) is valid shouldn't be hard, people should be used to that from userspace code calling free(), and if there are places where it's important to remember that the pointer might be NULL, then a simple comment would do, wouldn't it?
kfree(foo->bar); /* kfree(NULL) is valid */
the short version also have the real bennefits of generating shorter and faster code as well as being shorter "on-screen".
-- Jesper Juhl
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