On Wednesday, August 02, 2017 12:39:36 PM Hans Petter Selasky wrote: > On 08/02/17 12:13, Andriy Gapon wrote: > > > > As far as I understand a module initialization routine is executed via the > > sysinit mechanism. Specifically, module_register_init is set up as the > > sysinit > > function for every module and it calls MOD_EVENT(mod, MOD_LOAD) to invoke > > the > > module event handler. > > > > In linker_load_file() I see the following code: > > linker_file_register_sysctls(lf); > > linker_file_sysinit(lf); > > > > I think that this means that any statically declared sysctl-s in the module > > would be registered before the module receives the MOD_LOAD event. > > It's possible that some of the sysctl-s could have procedures as handlers > > and > > they might access data that is supposed to be initialized by the module > > event > > handler. > > > > So, for example, running sysctl -a at just the right moment during the > > loading > > of a module might end up in an expected behavior (including a crash). > > > > Is my interpretation of how the code works correct? > > Can the order of linker_file_sysinit and linker_file_register_sysctls be > > changed > > without a great risk? > > > > Thank you! > > > > P.S. > > The same applies to: > > linker_file_sysuninit(file); > > linker_file_unregister_sysctls(file); > > > > Hi, > > Not sure if this answers your question. > > If a SYSCTL() is TUNABLE, it's procedure can be called when the sysctl > is created. Else the SYSCTL() procedure callback might be called right > after it's registered. I think there is an own subsystem in sys/kernel.h > which takes care of the actual SYSCTL() creation/destruction - after the > linker is involved.
sysctl nodes are created explicitly via linker_file_register_sysctls, not via SYSINITs, so you can't order them with respect to other init functions. I think Andriy's suggestion of doing sysctls "inside" sysinits (so they are registered last and unregistered first) is probably better than the current state and is a simpler fix than changing all sysctls to use SYSINITs. -- John Baldwin _______________________________________________ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
