Re: [PATCH v3 14/25] tools/xenstore: change talloc_free() to take a const pointer

[Juergen Gross <jgross@xxxxxxxx>]

On 27.07.23 23:21, Julien Grall wrote:
> Hi Juergen,
>
> On 24/07/2023 12:02, Juergen Gross wrote:
> > With talloc_free() and related functions not taking a ponter to const
> typo: s/ponter/pointer/
>
> > it is tedious to use the const attribute for talloc()-ed memory in
> > many cases.
> >
> > Change the related prototypes to use "const void *" instead of
> > "void *".
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> > V3:
> > - new patch
> > ---
> >   tools/xenstore/talloc.c | 8 ++++----
> >   tools/xenstore/talloc.h | 4 ++--
> >   2 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/xenstore/talloc.c b/tools/xenstore/talloc.c
> > index 23c3a23b19..4f08dbec59 100644
> > --- a/tools/xenstore/talloc.c
> > +++ b/tools/xenstore/talloc.c
> > @@ -319,7 +319,7 @@ static int talloc_unreference(const void *context, const 
> > void *ptr)
> >     remove a specific parent context from a pointer. This is a more
> >     controlled varient of talloc_free()
> >   */
> > -int talloc_unlink(const void *context, void *ptr)
> > +int talloc_unlink(const void *context, const void *ptr)
> >   {
> >       struct talloc_chunk *tc_p, *new_p;
> >       void *new_parent;
> > @@ -499,7 +499,7 @@ void *talloc_init(const char *fmt, ...)
> >     should probably not be used in new code. It's in here to keep the talloc
> >     code consistent across Samba 3 and 4.
> >   */
> > -static void talloc_free_children(void *ptr)
> > +static void talloc_free_children(const void *ptr)
> >   {
> >       struct talloc_chunk *tc;
> > @@ -539,7 +539,7 @@ static void talloc_free_children(void *ptr)
> >      will not be freed if the ref_count is > 1 or the destructor (if
> >      any) returns non-zero
> >   */
> > -int talloc_free(void *ptr)
> > +int talloc_free(const void *ptr)
> >   {
> >       int saved_errno = errno;
> >       struct talloc_chunk *tc;
> > @@ -571,7 +571,7 @@ int talloc_free(void *ptr)
> >               goto err;
> >           }
> >           tc->destructor = (talloc_destructor_t)-1;
> > -        if (d(ptr) == -1) {
> > +        if (d((void *)ptr) == -1) {
> AFAICT, you can't propagate the const because the destructor may need to modify 
> the content. I guess this is a necessary evil here but it would be good to 
> document it.
Okay, will add a comment.


Juergen

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