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38db89799b
linux/drivers/char
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Alan Cox 38db89799b tty: throttling race fix 
The tty throttling code can race due to the lock drops. It takes very high
loads but this has been observed and verified by Rob Duncan.

The basic problem is that on an SMP box we can go

	CPU #1				CPU #2
	need to throttle ?
	suppose we should		buffer space cleared
					are we throttled
					yes ? - unthrottle
	call throttle method

This changeet take the termios lock to protect against this. The termios
lock isn't the initial obvious candidate but many implementations of throttle
methods already need to poke around their own termios structures (and nobody
really locks them against a racing change of flow control).

This does mean that anyone who is setting tty->low_latency = 1 and then
calling tty_flip_buffer_push from their unthrottle method is going to end up
collapsing in a pile of locks. However we've removed all the known bogus
users of low_latency = 1 and such use isn't safe anyway for other reasons so
catching it would be an improvement.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-11 08:50:59 -07:00
..
agp Merge branch 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2009-04-20 08:42:48 -07:00
hw_random virtio-rng: Remove false BUG for spurious callbacks 2009-04-24 13:28:30 -07:00
ip2 proc tty: switch ip2 to ->proc_fops 2009-04-01 08:59:08 -07:00
ipmi ipmi: fix ipmi_si modprobe hang 2009-05-22 07:30:41 -07:00
mwave mwave: struct device - replace bus_id with dev_name(), dev_set_name() 2009-01-06 10:44:38 -08:00
pcmcia tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
rio rio: addition has higher precedence than ?: 2009-04-06 14:36:43 -07:00
tpm TPM: get_event_name stack corruption 2009-05-20 08:30:05 +10:00
xilinx_hwicap xilinx_hwicap: remove improper wording in license statement 2008-12-17 11:23:07 -08:00
.gitignore
amiserial.c proc tty: switch amiserial to ->proc_fops 2009-04-01 08:59:10 -07:00
apm-emulation.c
applicom.c applicom: Auto-load applicom module when device opened. 2009-04-06 14:36:30 -07:00
applicom.h
bfin-otp.c
briq_panel.c
bsr.c trivial: drivers/char/bsr.c: Storage class should be before const qualifier 2009-03-30 15:22:02 +02:00
cd1865.h
ChangeLog
consolemap.c consolemap: indentation & braces disagree - reindent 2009-01-06 15:59:30 -08:00
cp437.uni unicode table for cp437 2008-12-13 11:25:49 -08:00
cs5535_gpio.c
cyclades.c tty: cyclades, remove unused variables 2009-06-11 08:50:58 -07:00
defkeymap.c_shipped
defkeymap.map
digi1.h
digiFep1.h
digiPCI.h
ds1302.c rtc: use bcd2bin/bin2bcd 2008-10-20 08:52:41 -07:00
ds1620.c [ARM] netwinder: clean up GPIO naming 2008-12-13 09:12:07 +00:00
dsp56k.c device create: char: convert device_create_drvdata to device_create 2008-10-16 09:24:42 -07:00
dtlk.c
efirtc.c
epca.c epca: fix test_bit parameters 2009-06-11 08:50:58 -07:00
epca.h
epcaconfig.h
esp.c esp: fix section mismatch warning 2009-04-07 08:31:03 -07:00
generic_nvram.c
generic_serial.c tty: Remove some pointless casts 2009-01-02 10:19:40 -08:00
genrtc.c
hangcheck-timer.c
hpet.c clocksource: pass clocksource to read() callback 2009-04-21 13:41:47 -07:00
hvc_beat.c powerpc/cell: Use correct types in beat files 2009-01-08 16:25:16 +11:00
hvc_console.c hvc_console: Remove tty->low_latency 2009-01-16 16:15:16 +11:00
hvc_console.h powerpc: Make open count variables signed in hvcs/hvsi/hvc_console 2008-12-03 21:04:13 +11:00
hvc_irq.c hvc_console: Call free_irq() only if request_irq() was successful 2009-01-13 14:48:01 +11:00
hvc_iseries.c drivers/hvc: Add missing of_node_put 2008-12-03 21:04:09 +11:00
hvc_iucv.c [S390] hvc_iucv: Provide IUCV z/VM user ID filtering 2009-03-26 15:24:08 +01:00
hvc_rtas.c
hvc_udbg.c powerpc: udbg-based backend for hvc_console 2008-11-19 16:04:25 +11:00
hvc_vio.c drivers/hvc: Add missing of_node_put 2008-12-03 21:04:09 +11:00
hvc_xen.c hvc_console: Add a hangup notifier for backends 2008-10-22 10:59:54 +11:00
hvcs.c hvc_console: Remove tty->low_latency on pseries backends 2009-03-11 10:44:26 +11:00
hvsi.c hvc_console: Remove tty->low_latency on pseries backends 2009-03-11 10:44:26 +11:00
i8k.c i8k: Add Dell Vostro systems 2009-01-02 10:28:32 -08:00
isicom.c tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
istallion.c tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
Kconfig NVRAM depends on RTC_DRV_CMOS 2009-01-31 01:21:59 +01:00
keyboard.c
lp.c device create: char: convert device_create_drvdata to device_create 2008-10-16 09:24:42 -07:00
Makefile Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc 2008-12-28 16:54:33 -08:00
mbcs.c
mbcs.h
mem.c drivers/char/mem.c: avoid OOM lockup during large reads from /dev/zero 2009-06-04 15:20:39 -07:00
misc.c device create: char: convert device_create_drvdata to device_create 2008-10-16 09:24:42 -07:00
mmtimer.c
moxa.c tty: moxa, fix refcounting in moxa_poll_port 2009-04-06 14:36:33 -07:00
moxa.h
mspec.c
mxser.c tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
mxser.h
n_hdlc.c
n_r3964.c tty: Remove some pointless casts 2009-01-02 10:19:40 -08:00
n_tty.c tty: N_TTY SIGIO only works for read 2009-01-02 10:19:40 -08:00
nozomi.c tty: kref nozomi 2009-01-02 10:19:40 -08:00
nsc_gpio.c
nvram.c [PATCH] nvram - convert PRINT_PROC to seq_file 2008-11-11 09:56:00 +00:00
nwbutton.c
nwbutton.h
nwflash.c [ARM] netwinder: clean up GPIO naming 2008-12-13 09:12:07 +00:00
pc8736x_gpio.c pc8736x_gpio: add support for PC87365 chips 2008-10-20 08:52:40 -07:00
ppdev.c device create: char: convert device_create_drvdata to device_create 2008-10-16 09:24:42 -07:00
ps3flash.c powerpc/ps3: Printing fixups for l64 to ll64 conversion drivers/char 2009-01-16 16:15:14 +11:00
pty.c pty: Fix documentation 2009-01-12 16:37:00 -08:00
random.c Avoid ICE in get_random_int() with gcc-3.4.5 2009-05-19 11:25:35 -07:00
raw.c Add a missing unlock_kernel() in raw_open() 2009-03-27 10:59:09 -06:00
riscom8_reg.h
riscom8.c riscom8: Auto-load riscom8 module when device opened. 2009-04-06 14:36:31 -07:00
riscom8.h
rocket_int.h tty: rocketport uses different port flags to everyone else 2009-01-02 10:19:39 -08:00
rocket.c rocket: fix test_bit parameters 2009-06-11 08:50:58 -07:00
rocket.h tty: rocketport uses different port flags to everyone else 2009-01-02 10:19:39 -08:00
rtc.c RTC: Remove the BKL. 2009-01-08 16:44:03 -07:00
scc.h m68k: atari - Rename "mfp" to "st_mfp" 2009-02-22 09:23:02 -08:00
scx200_gpio.c
selection.c Fix memory corruption in console selection 2009-01-31 15:51:31 -08:00
ser_a2232.c m68k: ser_a2232 - Kill warn_unused_result warnings 2009-01-12 20:56:39 +01:00
ser_a2232.h
ser_a2232fw.ax
ser_a2232fw.h
serial167.c tty: Remove some pointless casts 2009-01-02 10:19:40 -08:00
snsc_event.c
snsc.c device create: char: convert device_create_drvdata to device_create 2008-10-16 09:24:42 -07:00
snsc.h
sonypi.c Rationalize fasync return values 2009-03-16 08:34:35 -06:00
specialix_io8.h
specialix.c specialix: Auto-load specialix module when device opened. 2009-04-06 14:36:31 -07:00
stallion.c tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
sx.c sx.c: avoid referencing freed memory if copy_from_user() fails 2009-02-20 17:57:49 -08:00
sx.h
sxboards.h
sxwindow.h
synclink_gt.c tty: synclink_gt add receive pio mode 2009-06-11 08:50:57 -07:00
synclink.c tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
synclinkmp.c tty: Add carrier processing on close to the tty_port core 2009-06-11 08:50:56 -07:00
sysrq.c sysrq, intel_fb: fix sysrq g collision 2009-05-15 07:56:24 -05:00
tb0219.c
tlclk.c
toshiba.c
tty_audit.c Trim includes of fdtable.h 2009-03-31 23:00:28 -04:00
tty_buffer.c
tty_io.c pids: kill signal_struct-> __pgrp/__session and friends 2009-04-02 19:05:02 -07:00
tty_ioctl.c tty: throttling race fix 2009-06-11 08:50:59 -07:00
tty_ldisc.c Trim includes of fdtable.h 2009-03-31 23:00:28 -04:00
tty_port.c tty: Implement a drain delay in the tty port 2009-06-11 08:50:56 -07:00
vc_screen.c vcs: hook sysfs devices into object lifetime instead of "binding" 2009-03-24 16:38:26 -07:00
viotape.c device create: char: convert device_create_drvdata to device_create 2008-10-16 09:24:42 -07:00
virtio_console.c virtio_console: support console resizing 2008-12-30 09:26:10 +10:30
vme_scc.c m68k: vme_scc - Kill warn_unused_result warnings 2009-01-12 20:56:38 +01:00
vr41xx_giu.c drivers/char: use nr_irqs 2008-10-16 16:52:05 +02:00
vt_ioctl.c vt: Add a note on the historical abuse of CLOCK_TICK_RATE 2009-05-06 14:47:13 -07:00
vt.c Revert "console ASCII glyph 1:1 mapping" 2009-04-19 10:51:40 -07:00