Re: [PATCH] ext3_clear_inode(): avoid kfree(NULL)

[Andrew Morton]

On Fri, 23 Jun 2006 14:51:03 -0400
Jeff Garzik <jeff@xxxxxxxxxx> wrote:

> Linux Kernel Mailing List wrote:
> > commit e6022603b9aa7d61d20b392e69edcdbbc1789969
> > tree f94b059e312ea7b2f3c4d0b01939e868ed525fb0
> > parent 304c4c841a31c780a45d65e389b07706babf5d36
> > author Andrew Morton <akpm@xxxxxxxx> Fri, 23 Jun 2006 16:05:32 -0700
> > committer Linus Torvalds <torvalds@xxxxxxxxxxx> Fri, 23 Jun 2006 21:43:05 -0700
> > 
> > [PATCH] ext3_clear_inode(): avoid kfree(NULL)
> > 
> > Steven Rostedt <rostedt@xxxxxxxxxxx> points out that `rsv' here is usually
> > NULL, so we should avoid calling kfree().
> > 
> > Also, fix up some nearby whitespace damage.
> > 
> > Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
> > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxx>
> 
> Dumb question...  why?  kfree(NULL) has always been explicitly allowed.
> 

Because at that callsite, NULL is the common case.  We avoid a do-nothing
function call most of the time.  It's a nano-optimisation.
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