Commit 3821fd35b58d ("jump_label: Reduce the size of struct static_key")
broke old compilers that could not handle static initialization of anonymous
unions. Boris fixed it with a patch that added brackets around the static
initializer. But this creates a dependency between those initializers
and the structure's order of its fields. Document this dependency in
case new fields are added to struct static_key in the future.Noted-by: Boris Ostrovsky <[email protected]> Suggested-by: Chris Mason <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- include/linux/jump_label.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index a7f9011..28e04a33 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -90,6 +90,13 @@ extern bool static_key_initialized; struct static_key { atomic_t enabled; /* + * Note: + * To make anonymous unions work with old compilers, the static + * initialization of them requires brackets. This creates a dependency + * on the order of the struct with the initializers. If any fields + * are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need + * to be modified. + * * bit 0 => 1 if key is initially true * 0 if initially false * bit 1 => 1 if points to struct static_key_mod -- 2.9.3
