srcutree: Use export for srcu_struct defined by DEFINE_STATIC_SRCU()
If an srcu_struct structure defined by tree SRCU's DEFINE_STATIC_SRCU()
is used by a module, sparse will give the following diagnostic:
sparse: symbol '__srcu_struct_nodes_srcu' was not declared. Should it be static?
The problem is that a within-module DEFINE_STATIC_SRCU() must define
a non-static srcu_struct because it is exported by referencing it in a
special '__section("___srcu_struct_ptrs")'. This reference is needed
so that module load and unloading can invoke init_srcu_struct() and
cleanup_srcu_struct(), respectively. Unfortunately, sparse is unaware of
'__section("___srcu_struct_ptrs")', resulting in the above false-positive
diagnostic. To avoid this false positive, this commit therefore creates
a prototype of the srcu_struct with an "extern" keyword.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 8501b6b..44e9986 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -131,6 +131,7 @@ struct srcu_struct {
#ifdef MODULE
# define __DEFINE_SRCU(name, is_static) \
is_static struct srcu_struct name; \
+ extern struct srcu_struct * const __srcu_struct_##name; \
struct srcu_struct * const __srcu_struct_##name \
__section("___srcu_struct_ptrs") = &name
#else
