Re: known vboxgetty/isdn issue in 2.6.35.3?

From: Arnd Bergmann
Date: Fri Mar 18 2011 - 10:24:54 EST


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@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>

Arnd
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