Re: [PATCH] shm: fix a race between shm_exit() and shm_init()

[Manuel Lauss]

On Wed, Aug 3, 2011 at 9:43 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Aug 2, 2011 at 2:45 AM, Vasiliy Kulikov <segoon@xxxxxxxxxxxx> wrote:
>>
>> From: Vasiliy Kulikov <segoon@xxxxxxxxxxxx>
>> Subject: [PATCH] shm: fix a race between shm_exit() and shm_init()
>
> This patch is disgusting.
>
> Doing things like this:
>
>> +       /*
>> +        * For init_ipc_ns shm_ids().rw_mutex is statically initialized
>> +        * as kernel threads should be able to use it in do_exit() before
>> +        * shm_init(), which is called on do_initcall()
>> +        */
>> +       if (ns == &init_ipc_ns)
>> +               __ipc_init_ids(&shm_ids(ns));
>> +       else
>> +               ipc_init_ids(&shm_ids(ns));
>
> should have told you that there is something totally wrong with your patch.
>
> I'd prefer to really do the initialization in the allocator (at which
> point it would be very natural to do the initialization statically for
> a static allocation, and you wouldn't have the above kind of nasty
> conditional stuff), but that whole namespace initialization and setup
> just looks pretty nasty.
>
> Looking at some of the other cases like net_ns_init(), maybe the
> proper fix is to just make 'ipc_ns_init()' be a pure_initcall().
>
> Does the attached patch work?

No, same oops still.

Manuel
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