Messages in this thread | | | Date | Wed, 30 Jan 2013 11:10:58 +0100 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] tty: Prevent deadlock in n_gsm driver |
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On Wed, Jan 30, 2013 at 10:51:59AM +0100, Dirkjan Bussink wrote: > This change fixes a deadlock when the multiplexer is closed while there > are still client side ports open. > > When the multiplexer is closed and there are active tty's it tries to > close them with tty_vhangup. This has a problem though, because > tty_vhangup needs the tty_lock. This patch changes it to unlock the > tty_lock before attempting the hangup and relocks afterwards. The > additional call to tty_port_tty_set is needed because otherwise the > port stays active because of the reference counter. > > This change also exposed another problem that other code paths don't > expect that the multiplexer could have been closed. This patch also adds > checks for these cases in the gsmtty_ class of function that could be > called. > > The documentation explicitly states that "first close all virtual ports > before closing the physical port" but we've found this to not always > reality in our field situations. The GPRS / UTMS modem sometimes crashes > and needs a power cycle in that case which means cleanly shutting down > everything is not always possible. This change makes it much more robust > for our situation where at least the system is recoverable with this patch > and doesn't hang in a deadlock situation inside the kernel. > > The patch is against the long term support kernel (3.4.27) and should > apply cleanly to more recent branches. Tested with a Telit GE864-QUADV2 > and Telit HE910 modem. > > Signed-off-by: Dirkjan Bussink <dirkjan.bussink@nedap.com> > Cc: stable <stable@vger.kernel.org>
This patch breaks the build in the tty-next tree:
drivers/tty/n_gsm.c: In function ‘gsm_dlci_release’: drivers/tty/n_gsm.c:1713:3: error: too few arguments to function ‘tty_unlock’ In file included from drivers/tty/n_gsm.c:44:0: include/linux/tty.h:596:24: note: declared here drivers/tty/n_gsm.c:1715:3: error: too few arguments to function ‘tty_lock’ In file included from drivers/tty/n_gsm.c:44:0: include/linux/tty.h:595:24: note: declared here
Can you fix this up (get it to build on the linux-next tree) and resend it?
thanks,
greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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