Re: [PATCH v2 2/2] x86/uaccess: Drop the address space qualifier from put_user()

[Paul E. McKenney]

On Mon, Sep 14, 2026 at 07:58:23AM -0700, Paul E. McKenney wrote:
> On Mon, Sep 14, 2026 at 01:53:32PM +0000, Ricardo Ribalda wrote:
> > __typeof__() preserves every qualifier, the address space included.
> > 
> > When we do __typeof(*__user *int), we are declaring a __user integer,
> > which is pretty much meaningless. A value in a register or in the stack
> > does not live in the user address space.
> > 
> > This annotation did not trigger any error until a recent version of
> > smatch[1] started caring. And as a result of that now we have tens of
> > warnings like:
> > 
> >   drivers/media/usb/uvc/uvc_v4l2.c:1112:13: warning: incorrect type in argument 2 (different address spaces)
> >   drivers/media/usb/uvc/uvc_v4l2.c:1112:13:    expected void const *from
> >   drivers/media/usb/uvc/uvc_v4l2.c:1112:13:    got unsigned int __user *
> > 
> > Instead of __typeof__() use TYPEOF_UNQUAL(). It maps to
> > __typeof_unqual__() in recent compilers, so the address space annotation
> > is gone.
> > 
> > [1] https://github.com/error27/smatch/commit/e53027a4e816a772403baafa83c09e4a94c1cb8f
> > 
> > Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > Link: https://lore.kernel.org/r/20260825-unqual-v1-2-7024fb81b4f9@xxxxxxxxxxxx
> > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> 
> Queued for testing and review, thank you both!

GAH!!!  I actually queued the rcu_ref one and replied to the wrong
email, apologies for my confusion.  Or was it a hallucination?
You be the judge!  ;-)

0a45e252da65 ("rcu: Drop the address space qualifier from the dereference macros")

							Thanx, Paul

> > ---
> >  arch/x86/include/asm/uaccess.h | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> > index 3a0dd3c2b233..4e576c0b9131 100644
> > --- a/arch/x86/include/asm/uaccess.h
> > +++ b/arch/x86/include/asm/uaccess.h
> > @@ -172,7 +172,7 @@ extern void __put_user_nocheck_8(void);
> >  	int __ret_pu;							\
> >  	void __user *__ptr_pu;						\
> >  	register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX);		\
> > -	__typeof__(*(ptr)) __x = (x); /* eval x once */			\
> > +	TYPEOF_UNQUAL(*(ptr)) __x = (x); /* eval x once */		\
> >  	__typeof__(ptr) __ptr = (ptr); /* eval ptr once */		\
> >  	__chk_user_ptr(__ptr);						\
> >  	__ptr_pu = __ptr;						\
> > @@ -231,7 +231,7 @@ extern void __put_user_nocheck_8(void);
> >  
> >  #define __put_user_size(x, ptr, size, label)				\
> >  do {									\
> > -	__typeof__(*(ptr)) __x = (x); /* eval x once */			\
> > +	TYPEOF_UNQUAL(*(ptr)) __x = (x); /* eval x once */		\
> >  	__typeof__(ptr) __ptr = (ptr); /* eval ptr once */		\
> >  	__chk_user_ptr(__ptr);						\
> >  	switch (size) {							\
> > 
> > -- 
> > 2.55.0.1007.g17ff1f9808-goog
> > 
>