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4d9b109060
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| hvc | ||
| ipwireless | ||
| serial | ||
| vt | ||
| amiserial.c | ||
| bfin_jtag_comm.c | ||
| cyclades.c | ||
| ehv_bytechan.c | ||
| goldfish.c | ||
| isicom.c | ||
| Kconfig | ||
| Makefile | ||
| moxa.c | ||
| moxa.h | ||
| mxser.c | ||
| mxser.h | ||
| n_gsm.c | ||
| n_hdlc.c | ||
| n_r3964.c | ||
| n_tracerouter.c | ||
| n_tracesink.c | ||
| n_tracesink.h | ||
| n_tty.c | ||
| nozomi.c | ||
| pty.c | ||
| rocket_int.h | ||
| rocket.c | ||
| rocket.h | ||
| synclink_gt.c | ||
| synclink.c | ||
| synclinkmp.c | ||
| sysrq.c | ||
| tty_audit.c | ||
| tty_buffer.c | ||
| tty_io.c | ||
| tty_ioctl.c | ||
| tty_ldisc.c | ||
| tty_mutex.c | ||
| tty_port.c | ||