tree a225eb502ad7609007b3223042e0b8f2d7fd186d
parent 5235d8dd28ee81ef1c3613027ff0b3ad8fa750b0
author Alexander Aring <aahringo@redhat.com> 1643209434 -0500
committer Paul E. McKenney <paulmck@kernel.org> 1643226965 -0800

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>