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SubjectRe: 9pfs double kfree
On Mon, Mar 06, 2006 at 10:40:03AM +0200, Kai Makisara wrote:
> > Legal, but rather bad taste. Init to NULL, possibly assign the value
> > if kmalloc(), then kfree() unconditionally - sure, but that... almost
> > certainly one hell of a lousy cleanup logics somewhere.
> >
> I agree with you.
>
> However, a few months ago it was advocated to let kfree take care of
> testing the pointer against NULL and a load of patches like this:

That's different - that's _exactly_ the case I've mentioned above.

Moreover, that's exact match to standard behaviour of free(3):

C99 7.20.3.2(2):
The free function causes the space pointed to by ptr to be deallocated, that
is, made available for further allocation. If ptr is a null pointer, no action
occurs. Otherwise, if the argument does not match a pointer returned by the
calloc, malloc, or realloc function, or if the space has been deallocated by
a call to free or realloc, the behaviour is undefined.

IOW, free(NULL) is guaranteed to be no-op while double-free is nasal daemon
country.
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