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Paul E. McKenney 9b2e4f1880 rcu: Track idleness independent of idle tasks 
Earlier versions of RCU used the scheduling-clock tick to detect idleness
by checking for the idle task, but handled idleness differently for
CONFIG_NO_HZ=y.  But there are now a number of uses of RCU read-side
critical sections in the idle task, for example, for tracing.  A more
fine-grained detection of idleness is therefore required.

This commit presses the old dyntick-idle code into full-time service,
so that rcu_idle_enter(), previously known as rcu_enter_nohz(), is
always invoked at the beginning of an idle loop iteration.  Similarly,
rcu_idle_exit(), previously known as rcu_exit_nohz(), is always invoked
at the end of an idle-loop iteration.  This allows the idle task to
use RCU everywhere except between consecutive rcu_idle_enter() and
rcu_idle_exit() calls, in turn allowing architecture maintainers to
specify exactly where in the idle loop that RCU may be used.

Because some of the userspace upcall uses can result in what looks
to RCU like half of an interrupt, it is not possible to expect that
the irq_enter() and irq_exit() hooks will give exact counts.  This
patch therefore expands the ->dynticks_nesting counter to 64 bits
and uses two separate bitfields to count process/idle transitions
and interrupt entry/exit transitions.  It is presumed that userspace
upcalls do not happen in the idle loop or from usermode execution
(though usermode might do a system call that results in an upcall).
The counter is hard-reset on each process/idle transition, which
avoids the interrupt entry/exit error from accumulating.  Overflow
is avoided by the 64-bitness of the ->dyntick_nesting counter.

This commit also adds warnings if a non-idle task asks RCU to enter
idle state (and these checks will need some adjustment before applying
Frederic's OS-jitter patches (http://lkml.org/lkml/2011/10/7/246).
In addition, validation of ->dynticks and ->dynticks_nesting is added.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
 		2011-12-11 10:31:24 -08:00
..
ABI block: Revert "[SCSI] genhd: add a new attribute "alias" in gendisk" 2011-11-10 09:03:55 +01:00
DocBook Merge branch 'driver-core-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core 2011-11-21 20:36:26 -08:00
PCI doc: fix broken references 2011-09-27 18:08:04 +02:00
RCU rcu: Track idleness independent of idle tasks 2011-12-11 10:31:24 -08:00
accounting Documentation: update cgroupfs mount point 2011-06-15 21:52:50 -07:00
acpi ACPI, APEI, EINJ Param support is disabled by default 2011-08-03 11:15:59 -04:00
aoe Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
arm Merge branch 'next/deletion' of git+ssh://master.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc 2011-07-25 12:43:28 -07:00
auxdisplay
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blackfin doc: fix broken references 2011-09-27 18:08:04 +02:00
block Documentation: drop as block elevator reference in switching-sched.txt 2011-11-04 12:01:48 -07:00
blockdev cciss: auto engage SCSI mid layer at driver load time 2011-11-16 09:21:49 +01:00
cdrom doc: fix broken references 2011-09-27 18:08:04 +02:00
cgroups Documentation: Fix typo in freezer-subsystem.txt 2011-11-07 23:02:25 +01:00
connector Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
console doc: fix console doc typo 2010-02-24 13:51:32 +01:00
cpu-freq Fix documentation and comment typo 'no_hz' 2011-08-08 18:55:59 +02:00
cpuidle
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cris
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crypto
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development-process doc: fix broken references 2011-09-27 18:08:04 +02:00
device-mapper dm log userspace: fix comment hyphens 2011-10-31 20:21:22 +00:00
devicetree of: Add Silicon Image vendor prefix 2011-11-29 08:24:20 -06:00
driver-model docs/driver-model: Update device class docs 2011-08-24 16:01:24 -07:00
dvb [media] update az6027 firmware URL 2011-10-14 10:29:45 -03:00
early-userspace
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fault-injection fault-injection: update documentation with the mmc module param 2011-10-26 16:32:13 -04:00
fb udlfb: Enable fbcon access to framebuffer by default 2011-08-24 10:12:38 +00:00
filesystems Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2011-12-01 08:28:53 -08:00
firmware_class firmware: Update hotplug script 2010-08-05 13:53:34 -07:00
frv doc: fix broken references 2011-09-27 18:08:04 +02:00
hid HID: Move hiddev.txt to the new Documentation/hid directory 2011-03-22 11:43:51 +01:00
hwmon hwmon: (w83627ehf) Add support for the W83627UHG 2011-11-04 12:00:48 +01:00
i2c i2c: Fix device name for 10-bit slave address 2011-11-23 11:33:07 +01:00
i2o doc: i2o: fix typo 'Settting' 2011-06-07 16:06:01 +02:00
ia64 Fix common misspellings 2011-03-31 11:26:23 -03:00
ide
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infiniband Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-10-27 08:44:20 +02:00
ioctl ioctl: register LTTng ioctl 2011-09-12 11:50:56 -07:00
isdn doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
ja_JP Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2011-07-25 23:06:24 -07:00
kbuild doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
kdump kdump: update kexec-tools URL and Vivek's email 2010-11-25 14:36:38 +01:00
ko_KR Docs/Kconfig: Update: osdl.org -> linuxfoundation.org 2010-11-15 23:50:13 +01:00
laptops Documentation: thinkpad-acpi grammo fixes 2011-11-04 12:01:47 -07:00
leds Documentation: fix leds-class.txt duplicated word 2011-11-04 12:01:48 -07:00
m68k Documentation: add pointer to name_to_dev_t for root= values 2011-08-03 14:25:21 -10:00
make kbuild: introduce HDR_ARCH_LIST for headers_install_all 2010-12-14 22:16:19 +01:00
mips Fix common misspellings 2011-03-31 11:26:23 -03:00
misc-devices Fix common misspellings 2011-03-31 11:26:23 -03:00
mmc mmc: documentation of mmc non-blocking request usage and design. 2011-07-21 10:34:52 -04:00
mn10300
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mtd Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
namespaces
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netlabel Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
networking ipv4:correct description for tcp_max_syn_backlog 2011-12-06 13:02:28 -05:00
nfc NFC: Driver for NXP Semiconductors PN544 NFC chip. 2011-01-13 08:03:19 -08:00
parisc
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pcmcia pcmcia: use autoconfiguration feature for ioports and iomem 2010-09-29 17:20:24 +02:00
power PM / Sleep: Update documentation related to system wakeup 2011-11-28 22:14:45 +01:00
powerpc Fix common misspellings 2011-03-31 11:26:23 -03:00
pps pps: add parallel port PPS signal generator 2011-01-13 08:03:21 -08:00
prctl
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pti Kernel documentation for the PTI feature. 2011-05-13 16:31:00 -07:00
ptp ptp: Added a brand new class driver for ptp clocks. 2011-05-23 13:01:00 -07:00
rapidio RapidIO: documentation update 2011-11-02 16:07:02 -07:00
s390 [S390] remove tape block docu 2011-07-24 10:48:22 +02:00
scheduler sched: Add documentation for bandwidth control 2011-08-14 12:03:58 +02:00
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2011-10-28 16:44:18 -07:00
security doc: fix broken references 2011-09-27 18:08:04 +02:00
serial RS485: fix inconsistencies in the meaning of some variables 2011-11-15 12:13:44 -08:00
sh sh: clkfwk: Kill off unused clk_set_rate_ex(). 2010-11-15 18:25:12 +09:00
sound Merge branch 'fix/asoc' into for-linus 2011-12-06 13:22:28 +01:00
sparc
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spi doc: fix broken references 2011-09-27 18:08:04 +02:00
sysctl kernel/sysctl.c: add cap_last_cap to /proc/sys/kernel 2011-10-31 17:30:53 -07:00
target [SCSI] tcm_mod_builder.py: Fix generated *_drop_nodeacl() handler 2011-03-23 11:36:45 -05:00
telephony Fix common misspellings 2011-03-31 11:26:23 -03:00
thermal thermal: Add event notification to thermal framework 2011-01-12 00:08:35 -05:00
timers doc: fix broken references 2011-09-27 18:08:04 +02:00
trace mm: change isolate mode from #define to bitwise type 2011-10-31 17:30:44 -07:00
usb USB: linux-cdc-acm.inf: add support for the acm_ms gadget 2011-11-29 09:59:29 +09:00
vDSO Document the vDSO and add a reference parser 2011-07-14 17:57:09 -07:00
video4linux [media] gspca - zc3xx: New webcam 03f0:1b07 HP Premium Starter Cam 2011-09-23 23:31:12 -03:00
virtual Merge branch 'for-linus' of git://github.com/richardweinberger/linux 2011-11-02 09:45:39 -07:00
vm Merge branches 'slab/next' and 'slub/partial' into slab/for-linus 2011-10-26 18:09:12 +03:00
w1 Fix common misspellings 2011-03-31 11:26:23 -03:00
watchdog Documentation: watchdog: add guide how to convert drivers to new framework 2011-11-05 21:25:16 +01:00
wimax
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x86 x86-64, doc: Remove int 0xcc from entry_64.S documentation 2011-08-16 08:04:08 -07:00
zh_CN remove the messy code file Documentation/zh_CN/SubmitChecklist 2011-09-26 16:18:41 -07:00
.gitignore add random binaries to .gitignore 2010-04-08 11:34:34 +02:00
00-INDEX Documentation: add Ramoops usage description 2011-08-13 18:34:03 -07:00
BUG-HUNTING
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Changes Documentation/Changes: remove some really obsolete text 2011-07-11 16:48:38 -07:00
CodingStyle Documentation: update CodingStyle use of braces 2011-11-04 12:01:47 -07:00
DMA-API-HOWTO.txt Documentation/DMA-API-HOWTO.txt: fix misleading example 2011-07-26 16:49:45 -07:00
DMA-API.txt include/linux/dma-mapping.h: add dma_zalloc_coherent() 2011-11-02 16:07:02 -07:00
DMA-ISA-LPC.txt
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DMA-attributes.txt
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HOWTO Documentation: update LXR web link 2011-05-23 15:14:11 -07:00
IPMI.txt IPMI: Add the document description of ipmi_get_smi_info 2010-12-14 00:22:00 -05:00
IRQ-affinity.txt bitmap, irq: add smp_affinity_list interface to /proc/irq 2011-05-25 08:39:45 -07:00
IRQ.txt
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Intel-IOMMU.txt
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Makefile [media] Remove the old V4L1 v4lgrab.c file 2010-12-29 08:17:12 -02:00
ManagementStyle
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SAK.txt
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SM501.txt
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SecurityBugs Fix common misspellings 2011-03-31 11:26:23 -03:00
SubmitChecklist Documentation/SubmitChecklist: add RCU debug config options 2011-07-25 20:57:17 -07:00
SubmittingDrivers Documentation: SubmittingDrivers: fix Linus's git tree URL 2011-08-13 18:34:03 -07:00
SubmittingPatches Documentation: fix spelling error in SubmittingPatches 2011-08-13 18:34:02 -07:00
VGA-softcursor.txt
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applying-patches.txt
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atomic_ops.txt Documentation/atomic_ops.txt: avoid volatile in sample code 2011-05-26 17:12:34 -07:00
bad_memory.txt
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basic_profiling.txt
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binfmt_misc.txt Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
braille-console.txt
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bt8xxgpio.txt
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btmrvl.txt
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bus-virt-phys-mapping.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
cachetlb.txt mm: convert mm->cpu_vm_cpumask into cpumask_var_t 2011-05-25 08:39:21 -07:00
circular-buffers.txt Document Linux's circular buffering capabilities 2010-03-24 16:31:22 -07:00
coccinelle.txt scripts/coccinelle: update for compatability with Coccinelle 0.2.4 2010-12-03 12:27:01 +01:00
cpu-hotplug.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
cpu-load.txt
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cputopology.txt topology/sysfs: Provide book id and siblings attributes 2010-09-09 20:41:25 +02:00
dcdbas.txt
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debugging-modules.txt
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debugging-via-ohci1394.txt
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dell_rbu.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
devices.txt Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2010-10-28 09:35:11 -07:00
dmaengine.txt Improve slave/cyclic DMA engine documentation 2011-07-27 20:33:48 +05:30
dontdiff Documentation: update dontdiff file 2011-05-23 15:14:11 -07:00
dynamic-debug-howto.txt Merge branch 'docs-next' of git://git.lwn.net/linux-2.6 2011-03-27 19:46:59 -07:00
edac.txt Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
eisa.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
email-clients.txt Documentation: email-clients: Add better Thunderbird information 2011-08-13 18:34:03 -07:00
feature-removal-schedule.txt sysctl: make CONFIG_SYSCTL_SYSCALL default to n 2011-11-02 16:07:02 -07:00
flexible-arrays.txt flex_array: flex_array_prealloc takes a number of elements, not an end 2011-04-28 16:12:47 -04:00
futex-requeue-pi.txt
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gcov.txt
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gpio.txt Revert "gpiolib: annotate gpio-intialization with __must_check" 2011-01-13 17:26:46 -08:00
highuid.txt
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hw_random.txt
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hwspinlock.txt hwspinlock/core: register a bank of hwspinlocks in a single API call 2011-09-21 19:45:34 +03:00
init.txt init/main.c: improve usability in case of init binary failure 2010-03-06 11:26:29 -08:00
initrd.txt
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intel_txt.txt Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
io-mapping.txt
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io_ordering.txt
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iostats.txt Documentation/iostats.txt: bit-size reference etc. 2011-03-23 20:44:18 +01:00
irqflags-tracing.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
isapnp.txt
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java.txt
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kernel-doc-nano-HOWTO.txt docbook: warn on unused doc entries 2010-09-11 16:49:21 -07:00
kernel-docs.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
kernel-parameters.txt Merge branch 'iommu/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu 2011-12-09 08:08:14 -08:00
kmemcheck.txt
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kmemleak.txt Documentation: update kmemleak supported archs 2011-06-15 21:52:50 -07:00
kobject.txt kobject: documentation: Update to refer to kset-example.c. 2010-03-19 07:12:20 -07:00
kprobes.txt tree-wide: fix comment/printk typos 2010-11-01 15:38:34 -04:00
kref.txt kref: Fix typo in kref documentation 2011-03-07 13:20:05 -08:00
ldm.txt Documentation: update broken web addresses. 2010-08-04 15:21:40 +02:00
local_ops.txt
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lockdep-design.txt lockdep: Update documentation for lock-class leak detection 2011-12-11 10:31:23 -08:00
lockstat.txt Documentation: Add statistics about nested locks 2011-05-28 17:03:29 +02:00
logo.gif
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logo.txt
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magic-number.txt doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
mca.txt doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
md.txt md: update documentation for md/rdev/state sysfs interface 2011-07-28 11:31:48 +10:00
media-framework.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
memory-barriers.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
memory-hotplug.txt memory hotplug: Allow memory blocks to span multiple memory sections 2011-02-03 16:08:57 -08:00
memory.txt
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mono.txt
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mutex-design.txt mutex: Fix annotations to include it in kernel-locking docbook 2010-09-03 08:19:51 +02:00
nmi_watchdog.txt
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nommu-mmap.txt
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numastat.txt
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oops-tracing.txt module,bug: Add TAINT_OOT_MODULE flag for modules not built in-tree 2011-11-07 07:54:42 +10:30
padata.txt Documentation/padata.txt: fix typos etc. 2010-08-11 08:59:18 -07:00
parport-lowlevel.txt
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parport.txt
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pi-futex.txt
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pinctrl.txt drivers: create a pin control subsystem 2011-10-13 12:49:17 +02:00
pnp.txt doc: capitalization and other minor fixes in pnp doc 2010-02-05 12:22:44 +01:00
preempt-locking.txt
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printk-formats.txt Documentation: update printk-formats.txt 2011-06-15 21:52:50 -07:00
prio_tree.txt
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ramoops.txt Documentation: add Ramoops usage description 2011-08-13 18:34:03 -07:00
rbtree.txt Documentation: Update augmented rbtree documentation 2011-07-24 10:03:05 -07:00
rfkill.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
robust-futex-ABI.txt
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robust-futexes.txt
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rt-mutex-design.txt variable name fix to Documentation/rt-mutex-design.txt 2010-06-05 17:39:09 +02:00
rt-mutex.txt
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rtc.txt RTC: Fix up rtc.txt documentation to reflect changes to generic rtc layer 2011-03-09 11:25:10 -08:00
serial-console.txt
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sgi-ioc4.txt
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sgi-visws.txt
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sparse.txt update email address 2010-07-19 10:56:54 +02:00
spinlocks.txt Documentation/spinlocks.txt: Remove reference to sti()/cli() 2011-07-11 12:45:04 -07:00
stable_api_nonsense.txt doc: stable_api_nonsense.txt: fix paragraph to make more sense. 2011-03-30 12:02:05 +02:00
stable_kernel_rules.txt Update email address for stable patch submission 2011-10-18 13:58:59 -07:00
svga.txt
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sysfs-rules.txt Fix typos in comments 2010-03-16 11:47:56 +01:00
sysrq.txt documentation: update sysrq.txt magic sysrq keys 2010-10-26 17:32:41 -07:00
unaligned-memory-access.txt
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unicode.txt
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unshare.txt
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vgaarbiter.txt Documentation: fix vgaarbiter.txt typos etc. 2011-05-23 15:14:11 -07:00
video-output.txt
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volatile-considered-harmful.txt Documentation/volatile-considered-harmful.txt: correct cpu_relax() documentation 2010-03-24 16:31:20 -07:00
workqueue.txt workqueue: Document debugging tricks 2011-03-31 13:40:42 +02:00
xz.txt decompressors: add XZ decompressor module 2011-01-13 08:03:24 -08:00
zorro.txt
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