Re: [PATCH] remove redundant NULL checks before kfree() in drivers/video/

[Antonino A. Daplas]

On Monday 21 March 2005 05:49, Geert Uytterhoeven wrote:
> On Mon, 21 Mar 2005, Antonino A. Daplas wrote:
> > On Sunday 20 March 2005 06:59, Jesper Juhl wrote:
> > > Checking a pointer for NULL before calling kfree() on it is redundant,
> > > kfree() deals with NULL pointers just fine.
> > > This patch removes such checks from files in drivers/video/
> > >
> > > Since this is a fairly trivial change (and the same change made
> > > everywhere) I've just made a single patch for all the files and CC all
> > > authors/maintainers of those files I could find for comments. If
> > > spliting this into one patch pr file is prefered, then I can easily do
> > > that as well.
> >
> > [snip]
> >
> > > --- linux-2.6.11-mm4-orig/drivers/video/console/bitblit.c	2005-03-16
> > > 15:45:26.000000000 +0100 +++
> > > linux-2.6.11-mm4/drivers/video/console/bitblit.c	2005-03-19
> > > 22:27:39.000000000 +0100 @@ -199,8 +199,7 @@ static void
> > > bit_putcs(struct vc_data *vc
> > >  		count -= cnt;
> > >  	}
> > >
> > > -	if (buf)
> > > -		kfree(buf);
> > > +	kfree(buf);
> > >  }
> >
> > This is performance critical, so I would like the check to remain. A
> > comment may be added in this section.
>
> The first thing kfree() does is check for the NULL pointer. And since
> kfree() is used a lot, it's probably already in the cache.

It's not the kfree that matters, but the fact that buf is almost always NULL.

Tony


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