Re: [Bluez-devel] system freeze in 2.6.17-mh5

[Marcel Holtmann <marcel@holtmann.org>]

Hi Christoph,

> > > BUG: scheduling while atomic: swapper/0x00000100/0
> > >  <c02ecbd2> wait_for_completion+0x82/0xb6  <c0115504>
> > > default_wake_function+0x0/0x12 <c0115504>
> > > default_wake_function+0x0/0x12  <c0113c8e> wake_up_process+0xd/0xf
> > > <c02e8b6f> hidp_idle_timeout+0x0/0x10  <c01297e2>
> > > kthread_stop_sem+0x74/0x93 <c012976b> kthread_stop+0xb/0xe  <c01213bb>
> 
> > this looks like a problem with the kthread API. We converted BNEP, CMTP
> > and HIDP to it with 2.6.17-mh3. So a 2.6.17-mh2 kernel should work
> > without any problems.
> > 
> > Christoph, any ideas. Did you see a similar problem before.
> 
> kthread_stop can sleep, hidp_idle_timeout is called from a timer, thus
> running in softirq context.
> 
> Why does hidp try to tear down the thread on this timeout anyway?  It
> seems much more logical to me to only do it in hidp_del_connection so
> that it's symmetric to starting the thread in hidp_add_connection.

previously, it was only marking the connection for disconnect:

        atomic_inc(&session->terminate);
        hidp_schedule(session);

After the conversion to kthread API we call kthread_stop() directly and
this is not gonna work.

The hidp_del_connection() is triggered from userspace to terminate an
active HIDP session. Additionally we also need to terminate the HIDP
session after a certain amount of idle time to safe power. In general
the HID input device itself should take care of this, but some of them
simply don't.

Regards

Marcel



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