On Fri, Sep 20, 2024 at 02:50:02PM +0200, Gustavo A. R. Silva wrote: > This is like container_of() but it has an assert to ensure that it's > using the first struct member. >
I just remembered that Greg wanted this based on container_of_const(). Really container_of_const() should be renamed to container_of() and container_of() should be renamed to container_of_helper() and we would add a #define container_of_const container_of for the transition. > Co-developed-by: Dan Carpenter <[email protected]> > Signed-off-by: Dan Carpenter <[email protected]> > Signed-off-by: Gustavo A. R. Silva <[email protected]> > --- > include/linux/container_of.h | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/include/linux/container_of.h b/include/linux/container_of.h > index 713890c867be..928c5865c1b4 100644 > --- a/include/linux/container_of.h > +++ b/include/linux/container_of.h > @@ -22,6 +22,24 @@ > "pointer type mismatch in container_of()"); \ > ((type *)(__mptr - offsetof(type, member))); }) > > +/** > + * container_first - cast first member of a structure out to the containing > + * structure > + * @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. > + * > + * WARNING: any const qualifier of @ptr is lost. > + */ > +#define container_first(ptr, type, member) ({ > \ > + void *__mptr = (void *)(ptr); \ > + static_assert(__same_type(*(ptr), ((type *)0)->member) || \ > + __same_type(*(ptr), void), \ > + "pointer type mismatch in container_of()"); \ > + static_assert(offsetof(type, member) == 0, "not first member"); \ > + ((type *)(__mptr - offsetof(type, member))); }) > + > + I added too many blank lines. regards, dan carpenter
