Re: kfree(NULL)

[Steven Rostedt]

On Fri, 2006-04-21 at 13:30 -0700, Vernon Mauery wrote:
> On Friday 21 April 2006 12:22, you wrote:

> > What makes you confident that the static inline version gives a time
> > saving?
> 
> A static inline wrapper would mean that it wouldn't have to make a function 
> call just to check if the pointer is NULL.  A simple NULL check is faster 
> than a function call and then a simple NULL check.  In other words, there 
> would be no pushing and popping the stack.  In almost all cases, replacing an 
> inline function with a non-inline function means a trade-off between speed 
> and size.

Andrew Morton just submitted a patch to -mm that fixes the two problem
places that called kfree(NULL) more than it calls kfree(non-NULL).

Besides the places that are now fixed, the inline doesn't save much.
Since most cases kfree(non-NULL) is called, so the NULL is really an
unlikely case.  Thus you just increased the size of the kernel, for
virtually no speed savings.

-- Steve


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