341d9df85b
A sysctl can have a custom handler that may access data that is initialized via SYSINIT(9) or via a module event handler (also invoked via SYSINIT). Thus, it is not safe to allow access to the module's sysctl-s until the initialization is performed. Likewise, we should not allow access to teh sysctl-s after the module is uninitialized. The latter is easy to achieve by properly ordering linker_file_unregister_sysctls and linker_file_sysuninit. The former is not as easy for two reasons: - the initialization may depend on tunables which get set when sysctl-s are registered, so we need to set the tunables before running sysinit-s - the initialization may try to dynamically add more sysctl-s under statically defined sysctl nodes So, this change splits the sysctl setup into two phases. In the first phase the sysctl-s are registered as before but they are disabled and hidden from consumers. In the second phase, done after sysinit-s, normal access to the sysctl-s is enabled. The change should affect only dynamic module loading and unloading after the system boot-up. Nothing changes for sysctl-s compiled into the kernel and sysctl-s in preloaded modules. Discussed with: hselasky, ian, jhb Reviewed by: julian, kib MFC after: 2 weeks Sponsored by: Panzura Differential Revision: https://reviews.freebsd.org/D12545
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