Re: USB device cannot be reconnected and khubd "blocked for more than 120 seconds"

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On Tue, Jan 15, 2013 at 3:50 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
>
> For now, I'm gonna implement simple "I'm not gonna wait for myself"
> self-deadlock avoidance.

You can't really do that. Or rather, it won't *help*.

The thing is, the module loading in particular is not necessarily
happening in the same context as what *started* the module loading. A
module loader will request the module from user space, and then later
user space - through possibly a totally unrelated process - will
finish it. So there is no "myself". There's not even necessarily any
relationship that the kernel even knows about, because the module
loading request can have gone from usermode_helper over something like
dbus to systemd.

See?

There's a reason I asked for a warning for this. Or the "let's flag
the current thread if it ever started anything asynchronous". Because
it's complicated.

          Linus
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