Messages in this thread | | | Subject | Re: [PATCH 1/4] module: implement module_inhibit_unload() | From | (Jonathan Corbet) | Date | Mon, 24 Sep 2007 16:00:05 -0600 |
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Hi, Tejun,
I was just looking over these changes...
> + /* Don't proceed till inhibition is lifted. */ > + add_wait_queue(&module_unload_wait, &wait); > + set_current_state(TASK_UNINTERRUPTIBLE); > + if (atomic_read(&module_unload_inhibit_cnt)) > + schedule(); > + __set_current_state(TASK_RUNNING); > + remove_wait_queue(&module_unload_wait, &wait); > + > + mutex_lock(&module_mutex);
Maybe I'm missing something, but this looks racy to me. There's no check after schedule() to see if module_unload_inhibit_cnt is really zero, and nothing to keep somebody else from slipping in and raising it again afterward.
Given your description of this tool as a "sledgehammer," might it not be easier to just take and hold module_mutex for the duration of the unload block?
jon
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