sleep bug in taskqueue(9)
Hans Petter Selasky
hselasky at c2i.net
Fri Nov 12 08:55:04 UTC 2010
On Thursday 29 April 2010 01:59:58 Matthew Fleming wrote:
> It looks to me like taskqueue_drain(taskqueue_thread, foo) will not
> correctly detect whether or not a task is currently running. The check
> is against a field in the taskqueue struct, but for the taskqueue_thread
> queue with more than one thread, multiple threads can simultaneously be
> running a task, thus stomping over the tq_running field.
>
> I have not seen any problem with the code as-is in actual use, so this
> is purely an inspection bug.
>
> The following patch should fix the problem. Because it changes the size
> of struct task I'm not sure if it would be suitable for MFC.
>
1) The u_char is going to leave a hole in that structure on ARM platforms for
example.
2) The existing taskqueue implementation also has a missing check for the
pending count wrapping to zero. I.E. it should stick at 0xFFFF and not wrap to
0.
--HPS
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