[RESEND PATCH] sparse: use static inline for __chk_{user,io}_ptr()

From: Luc Van Oostenryck
Date: Thu Aug 06 2020 - 15:42:20 EST

__chk_user_ptr() & __chk_io_ptr() are dummy extern functions which
only exist to enforce the typechecking of __user or __iomem pointers
in macros when using sparse.

This typechecking is done by inserting a call to these functions.
But the presence of these calls can inhibit some simplifications
and so influence the result of sparse's analysis of context/locking.

Fix this by changing these calls into static inline calls with
an empty body.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
include/linux/compiler_types.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index b67930216e45..a9b6699f3934 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -11,8 +11,8 @@
# define __iomem __attribute__((noderef, address_space(__iomem)))
# define __percpu __attribute__((noderef, address_space(__percpu)))
# define __rcu __attribute__((noderef, address_space(__rcu)))
-extern void __chk_user_ptr(const volatile void __user *);
-extern void __chk_io_ptr(const volatile void __iomem *);
+static inline void __chk_user_ptr(const volatile void __user *ptr) { }
+static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
/* context/locking */
# define __must_hold(x) __attribute__((context(x,1,1)))
# define __acquires(x) __attribute__((context(x,0,1)))