lkml.org 
[lkml]   [2016]   [Mar]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: modules: set mod->state to GOING before going notifiers are called
+++ 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

\
 
 \ /
  Last update: 2016-03-10 06:42    [W:0.040 / U:0.428 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site