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Dirkjan Bussink 4d9b109060 tty: Prevent deadlock in n_gsm driver 
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>
 		2013-01-30 12:10:09 +01:00
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accessibility
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acpi ACPI: Check MSR valid bit before using P-state frequencies 2013-01-22 13:37:21 +01:00
amba Drivers: amba: remove __dev* attributes. 2013-01-03 15:57:02 -08:00
ata [libata] replace sata_settings with devslp_timing 2013-01-14 13:29:15 -05:00
atm Drivers: atm: remove __dev* attributes. 2013-01-03 15:57:04 -08:00
auxdisplay Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
base Merge remote-tracking branch 'regmap/fix/debugfs' into tmp 2013-01-24 19:04:16 +08:00
bcma Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-01-08 07:31:49 -08:00
block Various minor fixes, but a slightly more complex one to fix the per-cpu overload 2013-01-20 16:44:28 -08:00
bluetooth tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
bus Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
cdrom Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
char TTY: synclink: Convert + to | for bit operations 2013-01-30 00:09:58 -05:00
clk mvebu fixes for v3.8-rc5 2013-01-23 20:30:52 -08:00
clocksource Drivers: clocksource: remove __dev* attributes. 2013-01-03 15:57:15 -08:00
connector Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
cpufreq cpufreq: Add module aliases for acpi-cpufreq 2013-01-22 22:33:46 +01:00
cpuidle cpuidle: remove the power_specified field in the driver 2013-01-15 14:18:04 +01:00
crypto Drivers: crypto: remove __dev* attributes. 2013-01-03 15:57:02 -08:00
dca
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devfreq PM / devfreq: exynos4_bus: honor RCU lock usage 2013-01-22 13:28:40 +01:00
dio
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dma Merge branch 'fixes' of git://git.infradead.org/users/vkoul/slave-dma 2013-01-24 10:17:49 -08:00
edac Two error path fixes causing a crash and a Kconfig fix for an issue 2013-01-09 08:43:56 -08:00
eisa
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extcon
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firewire Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
firmware Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
gpio gpio: mvebu: Don't free chip label memory 2013-01-17 12:27:08 +01:00
gpu ttm: on move memory failure don't leave a node dangling 2013-01-21 13:45:23 +10:00
hid Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
hsi Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
hv Drivers: hv: balloon: Fix a memory leak 2013-01-17 11:58:00 -08:00
hwmon hwmon: (vexpress) Fix build error seen if CONFIG_OF_DEVICE is not set 2013-01-09 21:47:22 -08:00
hwspinlock
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i2c Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
ide Drivers: ide: remove __dev* attributes. 2013-01-03 15:57:03 -08:00
idle intel_idle: Don't register CPU notifier if we are not running. 2013-01-18 13:43:43 +01:00
iio Staging fixes for 3.8-rc3 2013-01-14 09:08:38 -08:00
infiniband Drivers: infinband: remove __dev* attributes. 2013-01-03 15:57:15 -08:00
input tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
iommu Drivers: iommu: remove __dev* attributes. 2013-01-03 15:57:14 -08:00
ipack tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
irqchip ARM: arm-soc: Device-tree updates, take 2 2012-12-14 14:42:53 -08:00
isdn tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
leds leds: leds-gpio: set devm_gpio_request_one() flags param correctly 2013-01-02 17:58:41 -08:00
lguest tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
macintosh Drivers: macintosh: remove __dev* attributes. 2013-01-03 15:57:14 -08:00
md Miscellaneous device-mapper fixes, cleanups and performance improvements. 2012-12-21 17:08:06 -08:00
media Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
memory Drivers: memory: remove __dev* attributes. 2013-01-03 15:57:14 -08:00
memstick
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message Drivers: message: remove __dev* attributes. 2013-01-03 15:57:14 -08:00
mfd mfd: vexpress-sysreg: Don't skip initialization on probe 2013-01-24 12:19:23 +00:00
misc Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
mmc Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
mtd Drivers: mtd: remove __dev* attributes. 2013-01-03 15:57:03 -08:00
net Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
nfc Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
nubus
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of of: Fix export of of_find_matching_node_and_match() 2012-12-19 10:58:53 +00:00
oprofile
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parisc Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
parport serial/8250: Add suport for later SUNIX (TIMEDIA) boards. 2013-01-30 00:08:22 -05:00
pci PCI updates for v3.8: 2013-01-22 16:36:23 -08:00
pcmcia ARM: arm-soc: Header cleanups 2012-12-12 11:45:16 -08:00
pinctrl ARM: arm-soc fixes for 3.8-rc 2013-01-08 18:53:56 -08:00
platform asus-laptop: Fix potential invalid pointer dereference 2013-01-07 12:33:48 -05:00
pnp PNP: Handle IORESOURCE_BITS in resource allocation 2013-01-03 13:10:53 +01:00
power ARM: arm-soc fixes for 3.8-rc 2013-01-08 18:53:56 -08:00
pps tty: Added a CONFIG_TTY option to allow removal of TTY 2013-01-18 16:15:27 -08:00
ps3 Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
ptp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-12-12 18:07:07 -08:00
pwm pwm: Changes for v3.8-rc1 2012-12-19 08:19:07 -08:00
rapidio Driver core updates for 3.8-rc1 2012-12-11 13:13:55 -08:00
regulator Merge remote-tracking branch 'regulator/fix/s5m8767' into tmp 2013-01-15 09:38:59 +09:00
remoteproc Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
rpmsg Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
rtc drivers/rtc/rtc-da9055.c: fix cross-section reference 2013-01-11 14:54:54 -08:00
s390 Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
sbus Drivers: sbus: remove __dev* attributes. 2013-01-03 15:57:03 -08:00
scsi Drivers: scsi: remove __dev* attributes. 2013-01-03 15:57:01 -08:00
sfi
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sh sh: clkfwk: bugfix: sh_clk_div_enable() care sh_clk_div_set_rate() if div6 2013-01-11 20:57:58 +09:00
sn Drivers: misc: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
spi spi/sh-hspi: fix return value check in hspi_probe(). 2012-12-19 15:11:41 +00:00
ssb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-01-08 07:31:49 -08:00
staging Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
target iscsi-target: Fix CmdSN comparison (use cmd->cmd_sn instead of cmd->stat_sn) 2013-01-10 21:00:37 -08:00
tc
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thermal Drivers: thermal: remove __dev* attributes. 2013-01-03 15:57:02 -08:00
tty tty: Prevent deadlock in n_gsm driver 2013-01-30 12:10:09 +01:00
uio ARM: arm-soc: SoC updates for 3.8 2012-12-12 12:05:15 -08:00
usb Merge 3.8-rc5 into tty-next 2013-01-25 13:27:36 -08:00
uwb
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vfio vfio-pci: Fix buffer overfill 2013-01-15 10:45:26 -07:00
vhost Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2012-12-15 14:25:10 -08:00
video This is yet another critical imxfb fixes held off by absence of FB 2013-01-23 20:35:02 -08:00
virt Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2012-12-18 09:58:09 -08:00
virtio Drivers: virtio: remove __dev* attributes. 2013-01-03 15:57:01 -08:00
vlynq Drivers: vlynq: remove __dev* attributes. 2013-01-03 15:57:01 -08:00
vme
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w1 Drivers: w1: remove last __devexit_p() instance 2013-01-03 15:57:01 -08:00
watchdog watchdog: twl4030_wdt: add DT support 2013-01-02 12:07:05 +01:00
xen Fixes: 2013-01-18 12:02:52 -08:00
zorro Drivers: zorro: remove CONFIG_HOTPLUG usage 2013-01-03 15:57:01 -08:00
Kconfig
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Makefile
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