[PATCH 1/2] rcu: Fix casting while dereferencing rcu pointers

[Ricardo Ribalda]

Recent versions of smatch preserved the address space qualifiers with
typeof()[1].

This fix has discovered an invalid casting in rcu dereference logic.

This patch fixes tens of smatch errors like the following:
./include/trace/events/vb2.h:46:1: warning: incorrect type in assignment (different address spaces)
./include/trace/events/vb2.h:46:1:    expected struct tracepoint_func *it_func_ptr
./include/trace/events/vb2.h:46:1:    got struct tracepoint_func __rcu *

[1] https://github.com/error27/smatch/commit/e53027a4e816a772403baafa83c09e4a94c1cb8f

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
 include/linux/rcupdate.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 44c07a66edff..80276cedda80 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -488,7 +488,7 @@ static __always_inline bool lockdep_assert_rcu_helper(bool c, const struct __ctx
 context_unsafe(								\
 	typeof(*p) *local = (typeof(*p) *__force)(p);			\
 	rcu_check_sparse(p, __rcu);					\
-	((typeof(*p) __force __kernel *)(local))			\
+	((TYPEOF_UNQUAL(*p) __force __kernel *)(local))			\
 )
 /**
  * unrcu_pointer - mark a pointer as not being RCU protected
@@ -503,7 +503,7 @@ context_unsafe(								\
 ({ \
 	typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
 	rcu_check_sparse(p, space); \
-	((typeof(*p) __force __kernel *)(local)); \
+	((TYPEOF_UNQUAL(*p) __force __kernel *)(local)); \
 }) )
 #define __rcu_dereference_check(p, local, c, space) \
 ({ \
@@ -511,19 +511,19 @@ context_unsafe(								\
 	typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
 	RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_check() usage"); \
 	rcu_check_sparse(p, space); \
-	((typeof(*p) __force __kernel *)(local)); \
+	((TYPEOF_UNQUAL(*p) __force __kernel *)(local)); \
 })
 #define __rcu_dereference_protected(p, local, c, space) \
 ({ \
 	RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_protected() usage"); \
 	rcu_check_sparse(p, space); \
-	((typeof(*p) __force __kernel *)(p)); \
+	((TYPEOF_UNQUAL(*p) __force __kernel *)(p)); \
 })
 #define __rcu_dereference_raw(p, local) \
 ({ \
 	/* Dependency order vs. p above. */ \
 	typeof(p) local = READ_ONCE(p); \
-	((typeof(*p) __force __kernel *)(local)); \
+	((TYPEOF_UNQUAL(*p) __force __kernel *)(local)); \
 })
 #define rcu_dereference_raw(p) __rcu_dereference_raw(p, __UNIQUE_ID(rcu))
 

-- 
2.55.0.897.gb25b4bd76c-goog