On Tue, Jan 29, 2013 at 09:49:52AM +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.
It doesn't apply cleanly to the linux-next tree, can you refresh this and resend it so that I can apply it? If you want it backported to the stable kernel releases, we can only do that after it gets into Linus's tree, see the file, Documentation/stable_kernel_rules.txt for details about this. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
