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1035b63d3c
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Paul Fulghum 1035b63d3c n_hdlc: fix read and write locking 
Fix locking in read and write code of n_hdlc line discipline.

2.6.36 replaced lock_kernel() with tty_lock().  The tty mutex is not
dropped automatically when the thread sleeps like the BKL.  This results
in a blocked read or write holding the tty mutex and stalling operations
by other devices that use the tty mutex.

A review of n_hdlc read and write code shows:
1. neither BKL or tty mutex are required for correct operation
2. read can block while read data is available if data is posted
   between availability check and call to interruptible_sleep_on()
3. write does not set process state to TASK_INTERRUPTIBLE
   on each pass through the processing loop which can cause
   unneeded scheduling of the thread

The unnecessary tty mutex references have been removed.

Read changed to use same code as n_tty read
for completing reads and blocking.

Write corrected to set process state to TASK_INTERRUPTIBLE on each pass
through processing loop.

Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-01-22 19:15:01 -08:00
..
accessibility
acpi ACPI / PM: Call suspend_nvs_free() earlier during resume 2011-01-20 18:30:17 -08:00
amba
ata kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
atm
auxdisplay
base kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
block Merge branch 'for-2.6.38/drivers' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:50:24 -08:00
bluetooth
cdrom Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:45:01 -08:00
char Merge branch 'akpm' 2011-01-20 17:02:14 -08:00
clk
clocksource
connector
cpufreq kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
cpuidle
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2011-01-13 10:25:58 -08:00
dca
dio
dma Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx 2011-01-17 10:54:41 -08:00
edac
eisa
firewire Merge branches 'fixes' and 'fwnet' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2011-01-21 13:34:39 -08:00
firmware kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
gpio Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6 2011-01-14 09:08:00 -08:00
gpu Merge branch 'akpm' 2011-01-20 17:02:14 -08:00
hid kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
hwmon hwmon: (lm93) Add support for LM94 2011-01-18 12:22:54 -08:00
i2c i2c: Encourage move to dev_pm_ops by warning on use of legacy methods 2011-01-14 22:03:50 +01:00
ide kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
idle
ieee802154
infiniband kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
input kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
isdn
leds drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking 2011-01-20 17:02:06 -08:00
lguest lguest: compile fixes 2011-01-20 21:37:29 +10:30
macintosh powerpc/macintosh: Fix wrong test in fan_{read,write}_reg() 2011-01-21 14:08:34 +11:00
mca
md block: restore multiple bd_link_disk_holder() support 2011-01-14 18:44:22 +01:00
media Merge branch 'media_fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2011-01-21 16:50:31 -08:00
memstick
message
mfd mfd: ab8500-core chip version cut 2.0 support 2011-01-14 12:38:18 +01:00
misc misc: Make AB8500_PWM driver depend on U8500 due to PWM breakage 2011-01-14 12:38:12 +01:00
mmc mmc: sdhci-of: fix build on non-powerpc platforms 2011-01-14 00:22:44 -07:00
mtd Merge git://git.infradead.org/mtd-2.6 2011-01-17 11:15:30 -08:00
net kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
nfc drivers/nfc/pn544.c: fix min_t warnings 2011-01-16 17:28:21 -08:00
nubus
of dt/flattree: Return virtual address from early_init_dt_alloc_memory_arch() 2011-01-15 22:01:58 -07:00
oprofile
parisc
parport
pci kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
pcmcia kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
platform Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2011-01-13 20:15:35 -08:00
pnp
power Merge git://git.infradead.org/battery-2.6 2011-01-14 09:25:59 -08:00
pps
ps3
rapidio
regulator regulator: Support MAX8998/LP3974 DVS-GPIO 2011-01-14 12:38:16 +01:00
rtc mfd: Support LP3974 RTC 2011-01-14 12:38:16 +01:00
s390 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2011-01-19 20:25:45 -08:00
sbus
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-post-merge-2.6 2011-01-14 16:29:49 -08:00
sfi
sh
sn
spi Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/upstream-linus 2011-01-18 14:28:48 -08:00
ssb kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
staging [media] staging/lirc: fix mem leaks and ptr err usage 2011-01-19 12:52:22 -02:00
target [SCSI] target: Add LIO target core v4.0.0-rc6 2011-01-14 10:12:29 -06:00
tc
telephony
thermal
tty n_hdlc: fix read and write locking 2011-01-22 19:15:01 -08:00
uio
usb kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
uwb
vhost
video backlight: fix 88pm860x_bl macro collision 2011-01-20 17:02:06 -08:00
virtio virtio: remove virtio-pci root device 2011-01-20 21:37:30 +10:30
vlynq
w1
watchdog
xen Merge branch 'xen/xenbus' of git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen 2011-01-20 16:37:28 -08:00
zorro
Kconfig [SCSI] target: Add LIO target core v4.0.0-rc6 2011-01-14 10:12:29 -06:00
Makefile Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 2011-01-20 16:39:23 -08:00