Messages in this thread | | | Date | Mon, 6 Dec 2021 17:38:42 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] sysctl: Add a group of macro functions to initcall the sysctl table of each feature |
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On Tue, 7 Dec 2021 09:13:20 +0800 Xiaoming Ni <nixiaoming@huawei.com> 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.
> --- a/fs/coredump.c > +++ b/fs/coredump.c > @@ -943,12 +943,7 @@ static struct ctl_table coredump_sysctls[] = { > { } > }; > > -static int __init init_fs_coredump_sysctls(void) > -{ > - register_sysctl_init("kernel", coredump_sysctls); > - return 0; > -} > -fs_initcall(init_fs_coredump_sysctls); > +kernel_sysctl_initcall(coredump_sysctls);
But this and several like it are functional changes.
> #endif /* CONFIG_SYSCTL */ > > ... > > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -132,12 +132,7 @@ static struct ctl_table inodes_sysctls[] = { > { } > }; > > -static int __init init_fs_inode_sysctls(void) > -{ > - register_sysctl_init("fs", inodes_sysctls); > - return 0; > -} > -early_initcall(init_fs_inode_sysctls); > +fs_sysctl_initcall(inodes_sysctls); > #endif
Here's another, of many.
Someone made the decision to use early_initcall() here (why?) and this patch switches it to late_initcall()! Worrisome. Each such stealth conversion should be explained and justified, shouldn't it?
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