Messages in this thread | | | Date | Mon, 5 Dec 2022 21:24:13 +0000 | From | Sakari Ailus <> | Subject | Re: [PATCH v2 1/4] container_of: add container_of_const() that preserves const-ness of the pointer |
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Hi Greg,
On Mon, Dec 05, 2022 at 01:12:03PM +0100, Greg Kroah-Hartman wrote: > container_of does not preserve the const-ness of a pointer that is > passed into it, which can cause C code that passes in a const pointer to > get a pointer back that is not const and then scribble all over the data > in it. To prevent this, container_of_const() will preserve the const > status of the pointer passed into it using the newly available _Generic() > method. > > Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> > Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: "Rafael J. Wysocki" <rafael@kernel.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > --- > v2: - removed one parameter, now matches container_of(), thanks to > suggestion from Sakari > - changed Jason's tag to suggested-by and reviewed-by > - added Andy's tag
Thanks for the update. For the set:
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > include/linux/container_of.h | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/include/linux/container_of.h b/include/linux/container_of.h > index 2008e9f4058c..1d898f9158b4 100644 > --- a/include/linux/container_of.h > +++ b/include/linux/container_of.h > @@ -22,4 +22,17 @@ > "pointer type mismatch in container_of()"); \ > ((type *)(__mptr - offsetof(type, member))); }) > > +/** > + * container_of_const - cast a member of a structure out to the containing > + * structure and preserve the const-ness of the pointer > + * @ptr: the pointer to the member > + * @type: the type of the container struct this is embedded in. > + * @member: the name of the member within the struct. > + */ > +#define container_of_const(ptr, type, member) \ > + _Generic(ptr, \ > + const typeof(*(ptr)) *: ((const type *)container_of(ptr, type, member)),\ > + default: ((type *)container_of(ptr, type, member)) \ > + ) > + > #endif /* _LINUX_CONTAINER_OF_H */
-- Kind regards,
Sakari Ailus
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