Commit db48d3e22a ("sys_sem: add build time definition macros")
recently introduced SYS_SEM_DEFINE() and defined it in terms of
Z_DECL_ALIGN() and __in_section() to force the _k_sem linker section.
It is however cleaner and less obscur to use Z_STRUCT_SECTION_ITERABLE()
and list the _sys_sem linker section alongside the _k_sem one.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
For systems with userspace, the sys_sem exist in user memory working
as counter semaphore for user mode thread. The implemention of sys_sem
is based on k_futex. And the majority of the synchronization operations
are performed in user mode to reduce the calling of system call.
And for systems without userspace enabled, sys_sem behaves like k_sem.
Fixes: #15139.
Signed-off-by: Wentong Wu <wentong.wu@intel.com>
