On Mon, 2021-12-06 at 17:38 -0800, Andrew Morton wrote:
On Tue, 7 Dec 2021 09:13:20 +0800 Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote:
To avoid duplicated code, add a set of macro functions to initialize the
sysctl table for each feature.
The system initialization process is as follows:
start_kernel () {
...
/* init proc and sysctl base,
* proc_root_init()-->proc_sys_init()-->sysctl_init_bases()
*/
proc_root_init(); /* init proc and sysctl base */
...
arch_call_rest_init();
}
arch_call_rest_init()-->rest_init()-->kernel_init()
kernel_init() {
...
kernel_init_freeable(); /* do all initcalls */
...
do_sysctl_args(); /* Process the sysctl parameter: sysctl.*= */
}
kernel_init_freeable()--->do_basic_setup()-->do_initcalls()
do_initcalls() {
for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++) {
do_initcall_level
}
The sysctl interface of each subfeature should be registered after
sysctl_init_bases() and before do_sysctl_args(). It seems that the sysctl
interface does not depend on initcall_levels. To prevent the sysctl
interface from being initialized before the feature itself. The
lowest-level late_initcall() is used as the common sysctl interface
registration level.
I'm not normally a fan of wrapping commonly-used code sequences into
magical macros, but this one does seem to make sense.
I wonder if it is possible to cook up a checkpatch rule to tell people
to henceforth use the magic macros rather than to open-code things in
the old way. Sounds hard.
Almost impossible for checkpatch.
Likely easier in coccinelle.