Messages in this thread Patch in this message | | | Date | Thu, 10 Mar 2016 00:08:31 -0500 | From | Jessica Yu <> | Subject | Re: modules: set mod->state to GOING before going notifiers are called |
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+++ Rusty Russell [10/03/16 13:57 +1030]: >Jessica Yu <jeyu@redhat.com> writes: >> In load_module(), the going notifiers are called during error handling >> when an error occurs after the coming notifiers have already been called. >> However, a module's state is still MODULE_STATE_COMING when the going >> notifiers are called in the error path. To be consistent, also set >> mod->state to MODULE_STATE_GOING before calling the going notifiers. >> >> Signed-off-by: Jessica Yu <jeyu@redhat.com> >> --- >> kernel/module.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/kernel/module.c b/kernel/module.c >> index 1981ae0..9e80576 100644 >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -3494,6 +3494,9 @@ static int load_module(struct load_info *info, const char __user *uargs, >> return do_init_module(mod); >> >> coming_cleanup: >> + mutex_lock(&module_mutex); >> + mod->state = MODULE_STATE_GOING; >> + mutex_unlock(&module_mutex); >> blocking_notifier_call_chain(&module_notify_list, >> MODULE_STATE_GOING, mod); > >Actually, reviewing this patch makes me realize it is wrong. > >We rely on the state of the module being MODULE_STATE_COMING here: > > static inline int strong_try_module_get(struct module *mod) > { > BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED); > if (mod && mod->state == MODULE_STATE_COMING) > return -EBUSY; > >We will just have to document that the notifier can be called with >a module in MODULE_STATE_COMING if it never succeeded its >initialization.
Ah, thanks for catching that. I think I remember seeing this conditional and assuming it wouldn't be a problem since GOING modules would fail in try_module_get() (as it is does not pass the module_is_live() test) and subsequently strong_try_module_get() would also fail.. But, I think I ought to review how module states interact before making a change like this, so, please ignore this patch.
Jessica
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