linux/drivers
Doug Anderson d208a3bf77 TTY: serial_core: Fix crash if DCD drop during suspend
This crash was showing up 100% of the time on Tegra CPUs when an
agetty was running on the serial port and the console was not running
on the serial port.  The reason the Tegra saw it so reliably is that
the Tegra CPU internally ties DTR to DCD/DSR.  That means when we
dropped DTR during suspend we would get always get an immediate DCD
drop.

The specific order of operations that were running:
* uart_suspend_port() would be called to put the uart in suspend mode
* we'd drop DTR (ops->set_mctrl(uport, 0)).
* the DTR drop would be looped back in the CPU to be a DCD drop.
* the DCD drop would look to the serial driver as a hangup
* the hangup would call uart_shutdown()
* ... suspend / resume happens ...
* uart_resume_port() would be called and run the code in the
  (port->flags & ASYNC_SUSPENDED) block, which would startup the port
  (and enable tx again).
* Since the UART would be available for tx, we'd immediately get
  an interrupt, eventually calling transmit_chars()
* The transmit_chars() function would crash.  The first crash would
  be a dereference of a NULL tty member, but since the port has been
  shutdown that was just a symptom.

I have proposed a patch that would fix the Tegra CPUs here (see
https://lkml.org/lkml/2011/10/11/444 - tty/serial: Prevent drop of DCD
on suspend for Tegra UARTs).  However, even with that fix it is still
possible for systems that have an externally visible DCD line to see a
crash if the DCD drops at just the right time during suspend: thus
this patch is still useful.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-10-19 13:07:19 -07:00
..
accessibility
acpi Merge branch 'battery' into release 2011-08-05 22:16:42 -04:00
amba
ata drivers/ata/sata_dwc_460ex.c: add missing kfree 2011-08-18 23:58:11 -04:00
atm
auxdisplay
base Merge branch 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2011-08-17 13:15:25 -07:00
bcma
block Merge branch 'stable/for-jens' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus 2011-08-09 20:43:26 +02:00
bluetooth
cdrom drivers/cdrom/cdrom.c: relax check on dvd manufacturer value 2011-08-02 12:43:50 +02:00
char net: Compute protocol sequence numbers and fragment IDs using MD5. 2011-08-06 18:33:19 -07:00
clk
clocksource
connector proc_fork_connector: a lockless ->real_parent usage is not safe 2011-07-28 18:26:32 -07:00
cpufreq
cpuidle cpuidle: stop depending on pm_idle 2011-08-03 19:06:37 -04:00
crypto n2_crypto: Attach on Niagara-T3. 2011-07-28 01:30:07 -07:00
dca
dio
dma Merge branch 'fixes' of master.kernel.org:/home/rmk/linux-2.6-arm 2011-08-10 17:37:17 -07:00
edac i7core_edac: fixed typo in error count calculation 2011-08-18 14:07:15 -07:00
eisa eisa/pci_eisa.c: fix BUG introduced by 005bdad7b8 2011-08-04 06:32:51 -10:00
firewire Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2011-08-21 18:13:19 -07:00
firmware Merge branch 'pstore-efi' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6 2011-08-02 21:18:39 -10:00
gpio Merge branch 'gpio/next' of git://git.secretlab.ca/git/linux-2.6 2011-08-01 06:13:48 -10:00
gpu Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/drm-intel 2011-08-19 23:07:08 -07:00
hid
hwmon hwmon: (ibmaem) add missing kfree 2011-08-11 10:14:18 -07:00
hwspinlock
i2c
ide drivers/ide/cy82c693.c: Add missing pci_dev_put 2011-08-04 01:30:34 -07:00
idle
ieee802154
infiniband Merge branches 'ipoib' and 'iser' into for-next 2011-08-17 10:57:43 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-08-03 22:00:09 -10:00
iommu
isdn TTY: use tty_wait_until_sent_from_close in other drivers 2011-08-25 09:00:42 -07:00
leds
lguest
macintosh
mca
md dm table: set flush capability based on underlying devices 2011-08-02 12:32:08 +01:00
media Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2011-07-30 00:08:53 -07:00
memstick
message Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2011-07-30 08:36:02 -10:00
mfd mfd: Fix mismatch in twl4030 mutex lock-unlock 2011-07-31 23:28:27 +02:00
misc mmc: cb710: fix possible pci_dev leak in cb710_pci_configure() 2011-08-13 14:50:23 -04:00
mmc mmc: dw_mmc: Fix DDR mode support. 2011-08-13 14:50:32 -04:00
mtd
net Merge branch 'for-davem' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless 2011-08-11 23:09:46 -07:00
nfc
nubus
of Revert "dt: add of_alias_scan and of_alias_get_id" 2011-08-04 11:26:24 +01:00
oprofile
parisc
parport parport_pc: release IO region properly if unsupported ITE887x card is found 2011-10-18 14:17:40 -07:00
pci pci: fix new kernel-doc warning in pci.c 2011-08-20 18:02:32 -07:00
pcmcia Merge git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6 2011-07-31 06:23:08 -10:00
platform acer-wmi: support Lenovo ideapad S205 wifi switch 2011-08-05 15:21:52 -04:00
pnp
power Merge git://git.infradead.org/battery-2.6 2011-07-31 06:24:50 -10:00
pps
ps3
ptp
rapidio
regulator Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6 2011-08-01 14:05:46 -10:00
rtc Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-08-17 10:28:33 -07:00
s390 [S390] qdio: Use kstrtoul_from_user 2011-08-03 16:44:21 +02:00
sbus
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2011-07-30 08:36:02 -10:00
sfi
sh Merge branch 'sh-latest' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-3.x 2011-08-01 06:10:16 -10:00
sn
spi spi/pl022: remove function cannot exit 2011-08-02 14:54:11 +01:00
ssb
staging TTY: serial, move 68360 driver to staging 2011-09-22 16:00:20 -07:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2011-08-03 15:12:09 -10:00
tc
telephony
thermal thermal: make THERMAL_HWMON implementation fully internal 2011-08-02 14:51:57 -04:00
tty TTY: serial_core: Fix crash if DCD drop during suspend 2011-10-19 13:07:19 -07:00
uio
usb USB: Serial: Add PID(0xF7C0) to FTDI SIO driver for a zeitcontrol-device 2011-08-10 22:11:45 -07:00
uwb
vhost
video savagedb: Fix typo causing regression in savage4 series video chip detection 2011-08-06 12:02:40 -07:00
virt
virtio
vlynq
w1
watchdog watchdog: Cleanup WATCHDOG_CORE help text 2011-08-02 08:23:07 +00:00
xen xen: self-balloon needs module.h 2011-08-16 07:23:34 -07:00
zorro
Kconfig
Makefile