Messages in this thread |  | | From | Keith Owens <> | Subject | Re: Linux 2.4.21-rc3 - ipmi unresolved | Date | Sun, 25 May 2003 17:57:21 +1000 |
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On Fri, 23 May 2003 23:38:53 +1000, Eyal Lebedinsky <eyal@eyal.emu.id.au> wrote: >The exports in ksyms are still necessary, and missing: > >depmod: *** Unresolved symbols in >/lib/modules/2.4.21-rc3/kernel/drivers/char/ipmi/ipmi_msghandler.o >depmod: panic_notifier_list >depmod: *** Unresolved symbols in >/lib/modules/2.4.21-rc3/kernel/drivers/char/ipmi/ipmi_watchdog.o >depmod: panic_notifier_list >depmod: panic_timeout
Danger Will Robinson: panic notification to modules is racy.
Registering via panic_notifier_list does not bump the module use count, a panic can occur while a module is being unloaded and you are dead. No big deal for panic, you are already dying, but it is just a symptom of a larger problem, yet another uncounted reference to module code. _ANY_ notifier callback to a module is racy, think very carefully before exporting any XXX_notifier_list.
I would go so far as to say that no XXX_notifier_list should be exported, that includes notifier_chain_register() itself. If a module needs to be notified then it should have glue code in the main kernel that does try_inc_mod_count() on the module before calling any module functions.
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