On Tue, 2009-03-24 at 03:46 -0700, Andrew Morton wrote:
> But I don't think we've seen a coherent description of what's actually
> _wrong_ with the current code. flush_cpu_workqueue() has been handling
> this case for many years with no problems reported as far as I know.
>
> So what has caused this sudden flurry of reports? Did something change in
> lockdep? What is this
>
> [ 537.380128] (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0
> [ 537.380128]
> [ 537.380128] but task is already holding lock:
> [ 537.380128] (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
>
> supposed to mean? "events" isn't a lock - it's the name of a kernel
> thread, isn't it? If this is supposed to be deadlockable then how?
events is indeed the schedule_work workqueue thread name -- I just used
that for lack of a better name.
> Because I don't immediately see what's wrong with e1000_remove() calling
> flush_work(). It's undesirable, and we can perhaps improve it via some
> means, but where is the bug?
There is no bug -- it's a false positive in a way. I've pointed this out
in the original thread, see
http://thread.gmane.org/gmane.linux.kernel/550877/focus=550932
johannes
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