From: Arnd Bergmann <arnd@arndb.de>
To: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Subject: Re: known vboxgetty/isdn issue in 2.6.35.3?
Date: Fri, 18 Mar 2011 15:24:33 +0100
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Cc: Udo van den Heuvel <udovdh@xs4all.nl>, Karsten Keil <isdn@linux-pingi.de>,
        Greg KH <gregkh@suse.de>, linux-kernel@vger.kernel.org,
        Alan Cox <alan@linux.intel.com>, Tilman Schmidt <tilman@imap.cc>,
        stable@kernel.org
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On Thursday 17 March 2011, Michael Karcher wrote:
> The same issue happened on our system. Sometimes vboxgetty gets stuck in
> state D on a debian stable system (2.6.32). I just applied your patch to
> that kernel and hope the problem went away. Please remind me to report
> back in one to two weeks if I didn't already report whether the hangs
> are fixed. Is something except for a test on a productive system missing
> to get this fix into 32-stable?

Thanks for the report. You are talking about this patch, right?

bc10f96757 "isdn: avoid calling tty_ldisc_flush() in atomic context"

    Remove the call to tty_ldisc_flush() from the RESULT_NO_CARRIER
    branch of isdn_tty_modem_result(), as already proposed in commit
    00409bb045887ec5e7b9e351bc080c38ab6bfd33.
    This avoids a "sleeping function called from invalid context" BUG
    when the hardware driver calls the statcallb() callback with
    command==ISDN_STAT_DHUP in atomic context, which in turn calls
    isdn_tty_modem_result(RESULT_NO_CARRIER, ~), and from there,
    tty_ldisc_flush() which may sleep.
    
    Signed-off-by: Tilman Schmidt <tilman@imap.cc>
    Signed-off-by: David S. Miller <davem@davemloft.net>

	Arnd
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