original_kernel/drivers
Alan Cox 8077088449 n_tty: Fix echo race
If a tty in N_TTY mode with echo enabled manages to get itself into a state
where
	- echo characters are pending
	- FASYNC is enabled
	- tty_write_wakeup is called from either
		- a device write path (pty)
		- an IRQ (serial)

then it either deadlocks or explodes taking a mutex in the IRQ path.

On the serial side it is almost impossible to reproduce because you have to
go from a full serial port to a near empty one with echo characters
pending. The pty case happens to have become possible to trigger using
emacs and ptys, the pty changes having created a scenario which shows up
this bug.

The code path is

	n_tty:process_echoes() (takes mutex)
	tty_io:tty_put_char()
	pty:pty_write  (or serial paths)
	tty_wakeup     (from pty_write or serial IRQ)
	n_tty_write_wakeup()
	process_echoes()
	*KABOOM*

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-16 09:19:16 -07:00
..
accessibility
acpi
amba
ata ahci: add device ID for 82801JI sata controller 2009-07-14 22:42:56 -04:00
atm
auxdisplay
base
block
bluetooth
cdrom
char n_tty: Fix echo race 2009-07-16 09:19:16 -07:00
clocksource
connector
cpufreq
cpuidle
crypto
dca
dio
dma
edac
eisa
firewire
firmware
gpio
gpu
hid
hwmon
i2c
ide
idle
ieee1394
ieee802154
infiniband
input
isdn
leds
lguest
macintosh
mca
md
media
memstick
message
mfd
misc
mmc
mtd
net Revert "ppp: Fix throttling bugs" 2009-07-16 09:14:23 -07:00
nubus
of
oprofile
parisc
parport
pci
pcmcia
platform
pnp
power
pps
ps3
rapidio
regulator
rtc
s390
sbus
scsi
serial drivers/serial/bfin_sport_uart.c: remove wrong and unneeded memset 2009-07-16 09:19:16 -07:00
sh
sn
spi
ssb
staging
tc
telephony
thermal
uio
usb
uwb
video
virtio
vlynq
w1
watchdog
xen
zorro
Kconfig
Makefile