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The wakeup latency histograms (time between wakeup of a task and its
context switch) already cover a large variety of situations that may
lead to task latencies. However, in a situation where interrupts are
disabled too long, the start of the timer interrupt routine may already
be delayed, but the duration between task wakeup and its context switch
may not be increased. If only wakeup latency recordings were available,
such latencies would be missed. Therefore, histograms of offsets of
missed timer interrupts were introduced earlier. These histograms were
able to correctly monitor timers that failed to execute in time.
However, the recordings still contained a lot of noise.
This patch limits the recorded missed timer offsets to timers
- that contain a task to be woken up
- the task of which is an RT task
- the task of which has a higher priority than the current task
In addition, this patch contains several additions, fixes and cleanups -
most of them have no impact on the interfaces, except that the output
format of the task data (max_latency_CPU?) have been adapted to
facilitate scanning and to mark empty data. The new format is
"<pid> <priority> <latency> <command>"
separated by a single space. The priority is given in user space format,
i.e. the highest RT priority is 99, and the lowest is 1. If no data are
available so far, pid is set to -1, priority to 100, latency to -1 and
the command to an empty string.
The documentation "Documentation/trace/histograms.txt" was adapted
accordingly.
Example running on a two-way machine:
# cd /sys/kernel/debug/tracing/latency_hist/missed_timer_offsets
# ls max_latency-CPU?
max_latency-CPU0 max_latency-CPU1
# cat max_latency-CPU?
-1 100 -1
-1 100 -1
# chrt 99 sleep 1
# cat max_latency-CPU?
-1 100 -1
12024 99 2 sleep
The output indicates that the responsible timer to wakeup the process
with pid 12024, priority 99 and command "sleep" was running on CPU #1
and delayed by 2 microseconds.
The format of the histogram has not changed and is identical to the
wakeup latency histograms.
# grep -v " 0$" CPU1
#Minimum latency: 2 microseconds
#Average latency: 2 microseconds
#Maximum latency: 2 microseconds
#Total samples: 1
#There are 0 samples lower than 0 microseconds.
#There are 0 samples greater or equal than 10240 microseconds.
#usecs samples
2 1
For the continuous recording of a system's worst-case latency under
production conditions, both the wakeup latency and the missed timer
offsets must be observed. The maximum of the two latencies represents a
system's empirically derived worst-case latency. It is recommended to
use the output of the files "max_latency-CPU?", since listing this file
does not interfer with the recording.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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ssh://master.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.31.y
into rt/2.6.31
Conflicts:
Makefile
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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commit 518c8df77c21b7d1690dd8b96eb0e54c4ec1c9c1 upstream.
Signed-off-by: Rafal Milecki <zajec5@gmail.com>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Surbhi Palande <surbhi.palande@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit a0bb108112a872c0b0c4b3ef4974f95fb75b155d upstream.
This patch (as1311) fixes a problem in usb-storage: Some devices are
pretty broken when it comes to reporting sense data. The information
they send back indicates that they have more than 18 bytes of sense
data available, but when the system asks for more than 18 they fail or
hang. The symptom is that probing fails with multiple resets.
The patch adds a new BAD_SENSE flag to indicate that usb-storage
should never ask for more than 18 bytes of sense data. The flag can
be set in an unusual_devs entry or via the "quirks=" module parameter,
and it is set automatically whenever a REQUEST SENSE command for more
than 18 bytes fails or times out.
An unusual_devs entry is added for the Agfa photo frame, which uses a
Prolific chip having this bug.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Daniel Kukula <daniel.kuku@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.31.y
into rt/2.6.31
Conflicts:
Makefile
kernel/perf_counter.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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(cherry picked from commit e3bb52ae2bb9573e84c17b8e3560378d13a5c798)
Users on the linux-ext4 list recently complained about differences
across filesystems w.r.t. how to mount without a journal replay.
In the discussion it was noted that xfs's "norecovery" option is
perhaps more descriptively accurate than "noload," so let's make
that an alias for ext4.
Also show this status in /proc/mounts
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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(cherry picked from commit 5328e635315734d42080de9a5a1ee87bf4cae0a4)
It is anticipated that when sb_issue_discard starts doing
real work on trim-capable devices, we may see issues. Make
this mount-time optional, and default it to off until we know
that things are working out OK.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit 6baefab531b22288be3b4ddef5671ea6469b09f8 upstream.
Signed-off-by: Denis Loginov <dinvlad@gmail.com>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.31.y
into rt/2.6.31
Conflicts:
Makefile
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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[ Upstream commit 09d3f3f0e02c8a900d076c302c5c02227f33572d ]
Many years ago when this driver was written, it had a use, but these
days it's nothing but trouble and distributions should not enable it
in any situation.
Pretty much every console device a sparc machine could see has a
bonafide real driver, making the PROM console hack unnecessary.
If any new device shows up, we should write a driver instead of
depending upon this crutch to save us. We've been able to take care
of this even when no chip documentation exists (sunxvr500, sunxvr2500)
so there are no excuses.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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A source of system latencies not yet considered in the histograms
of effective latencies are delayed timer interrupts. Such latencies
are mainly due to disabled interrupts. Recording of effective latencies
allows to continuously monitor a system's real-time capabilities
under real-world conditions.
This patch adds latency histograms of missed timer offsets. If the
timer belongs to a sleeper that is about to wakeup a task and the
latency is higher than previous latencies of such timers, some data
of this task are recorded as well.
Adapted and expanded Documentation/trace/histograms.txt.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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The algorithm used so far to trace the process with the highest priority
requires that no other processes with the same priority are being woken
up simultaneously. Otherwise, a process with a lower priority may be
picked up for tracing which leads to an erroneously high latency value.
Generally, the wakeup latency of a process that exclusively uses the
highest priority of the system is due to software or hardware issues we
would like to solve or, at least, keep as small as possible. This is
what latency measurements are made for, after all. The wakeup latency of
a process that shares the highest priority of the system with other
processes, is quite another story. It may contain the worst-case runtime
durations of the other processes; thus, it is the result of the priority
design of a given system and nothing a kernel developer or hardware
engineer may want to fix.
This said, we need to separately record latencies i) of processes that
exclusively use the highest priority of the system and ii) of processes
that share the highest priority of the system with other processes.
The above mentioned shortcoming of the tracing algorithm also applies to
the variable tracing_max_latency that the wakeup latency tracer uses,
since it is based on the same procedure as the original version of the
latency histogram. In consequence, if several processes share the
highest priority of the system, the variable tracing_max_latency may
contain erroneously high values. We could now patch the wakeup latency
tracer as well and separately record the various latencies, but we
better document this behavior and recommend the latency histograms to
reliably determine a system's worst-case wakeup latency.
Simplified and cleaned up a bit. Added some more help info to Kconfig.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Merge branch 'master' of
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.31.y
into rt/2.6.31
Conflicts:
Makefile
kernel/futex.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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commit 7069331dbe7155f23966f5944109f909fea0c7e4 upstream
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Merge branch 'master' of
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.31.y
into rt/2.6.31
Conflicts:
Makefile
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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commit b607bd900051efc3308c4edc65dd98b34b230021 upstream.
Which is why I have always preferred sizeof(struct foo) over
sizeof(var).
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Resuscitated and enhanced the kernel latency histograms provided
originally by Yi Yang and adapted and converted by Steven Rostedt.
Latency histograms in the current version
- can be enabled online and independently
- have virtually no performance penalty when configured but not enabled
- have very little performance penalty when enabled
- use already available wakeup and switch tracepoints
- give corresponding results with the related tracer
- allow to record wakeup latency histograms of a single process
- record the process where the highest wakeup latency occurred
- are documented in Documentation/trace/histograms.txt
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4AAEDDD5.4040505@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Conflicts:
kernel/trace/ring_buffer.c
kernel/trace/trace.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Documentation for event filters and formats.
v2 changes: fix a few problems noticed by Randy Dunlap.
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1252642431.8016.9.camel@tropicana>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into tracing/core
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Merge reason: move from -rc5 to -rc9.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The latency_trace file got removed a while back by commit
886b5b73d71e4027d7dc6c14f5f7ab102201ea6b and has been replaced
by the latency-format option.
This patch fixes the documentation by reflecting this change.
Changes since v1:
- mention that the trace format is configurable through the
latency-format option
- Fix a couple mistakes related to the timestamps
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090831204007.GE4237@pc-ras4041.res.insa>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
9p: update documentation pointers
9p: remove unnecessary v9fses->options which duplicates the mount string
net/9p: insulate the client against an invalid error code sent by a 9p server
9p: Add missing cast for the error return value in v9fs_get_inode
9p: Remove redundant inode uid/gid assignment
9p: Fix possible regressions when ->get_sb fails.
9p: Fix v9fs show_options
9p: Fix possible memleak in v9fs_inode_from fid.
9p: minor comment fixes
9p: Fix possible inode leak in v9fs_get_inode.
9p: Check for error in return value of v9fs_fid_add
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function_graph traces look like nested function calls, complete with
braces denoting the start and end of functions. function-graph-fold.vim
teaches vim how to fold these functions, to make it more convenient to
browse them.
To use, :source function-graph-fold.vim while viewing a function_graph
trace, or use "view -S function-graph-fold.vim some-trace" to load it
from the command-line together with a trace. You can then use the usual
vim fold commands, such as "za", to open and close nested functions.
While closed, a fold will show the total time taken for a call, as would
normally appear on the line with the closing brace. Folded functions
will not include finish_task_switch(), so folding should remain
relatively sane even through a context switch.
Note that this will almost certainly only work well with a single-CPU
trace (e.g. trace-cmd report --cpu 1). It also takes some time to run
(a few seconds for a large trace on my laptop). Nevertheless, I found
it very handy to get an overview of a trace and then drill down on
problematic calls.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
LKML-Reference: <20090806145701.GB7661@feather>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Fix some issues with the AFS documentation, found when testing AFS on ppc64:
- Update AFS features: reading/writing, local caching
- Typo in kafs sysfs debug file
- Use modprobe instead of insmod in example
- Update IPs for grand.central.org
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The commit 2ff05b2b (oom: move oom_adj value) moveed the oom_adj value to
the mm_struct. It was a very good first step for sanitize OOM.
However Paul Menage reported the commit makes regression to his job
scheduler. Current OOM logic can kill OOM_DISABLED process.
Why? His program has the code of similar to the following.
...
set_oom_adj(OOM_DISABLE); /* The job scheduler never killed by oom */
...
if (vfork() == 0) {
set_oom_adj(0); /* Invoked child can be killed */
execve("foo-bar-cmd");
}
....
vfork() parent and child are shared the same mm_struct. then above
set_oom_adj(0) doesn't only change oom_adj for vfork() child, it's also
change oom_adj for vfork() parent. Then, vfork() parent (job scheduler)
lost OOM immune and it was killed.
Actually, fork-setting-exec idiom is very frequently used in userland program.
We must not break this assumption.
Then, this patch revert commit 2ff05b2b and related commit.
Reverted commit list
---------------------
- commit 2ff05b2b4e (oom: move oom_adj value from task_struct to mm_struct)
- commit 4d8b9135c3 (oom: avoid unnecessary mm locking and scanning for OOM_DISABLE)
- commit 8123681022 (oom: only oom kill exiting tasks with attached memory)
- commit 933b787b57 (mm: copy over oom_adj value at fork time)
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
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Conflicts:
fs/xfs/xfs_fsops.c
kernel/futex.c
kernel/irq/manage.c
kernel/perf_counter.c
Fixup of kernel/rtmutex.c vs. atomic_spinlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Thanks to hermann pitton <hermann-pitton@arcor.de> for pointing this new
variation.
Tested-by: hermann pitton <hermann-pitton@arcor.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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WinTV-HVR1120 DVB-T/Hybrid
Signed-off-by: Michael Krufky <mkrufky@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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WinTV-HVR1150 ATSC/QAM-Hybrid
Signed-off-by: Michael Krufky <mkrufky@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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By default the kernel honors the HPA (host protected area) of hard
drives. Using libata's ignore_hpa module option it's possible to
change this behaviour.
Document usage and options of libata.ignore_hpa in
Documentation/kernel-parameters.txt.
Signed-off-by: Michael Prokop <mika@grml.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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Conflicts:
kernel/perf_counter.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Conflicts:
kernel/trace/trace_events_filter.c
We use the tracing/core version.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This will register the ioctl range used by nilfs2 file system to the
table listed in Documentation/ioctl/ioctl-number.txt.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
lockdep: Fix typos in documentation
lockdep: Fix file mode of lock_stat
rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock()
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* master.kernel.org:/home/rmk/linux-2.6-arm: (30 commits)
ARM: 5639/1: arm: clkdev.c should include <linux/clk.h>
ARM: 5638/1: arch/arm/kernel/signal.c: use correct address space for CRUNCH
ARM: 5637/1: [KS8695] Don't reference CLOCK_TICK_RATE in drivers
ARM: S3C64XX: serial: Fix section mismatch warning
ARM: S3C24XX: serial: Fix section mismatch warnings
ARM: S3C: PWM fix for low duty cycle
ARM: 5597/1: [PCI] reset all internal hardware prior PCI initialization
ARM: 5627/1: Fix restoring of lr at the end of mcount
ARM: 5624/1: Document cache aliasing region
S3C64XX: Fix ARMCLK configuration
S3C64XX: Fix get_rate() for ARMCLK
S3C24XX: GPIO: Fix pin range check in s3c_gpiolib_getchip
mx3 defconfig update
mx27 defconfig update
ARM: 5623/1: Treo680: ir shutdown typo fix
ARM: includecheck fix: plat-stmp3xxx/pinmux.c
ARM: includecheck fix: plat-s3c64xx/pm.c
ARM: includecheck fix: mach-omap2/mcbsp.c
ARM: includecheck fix: mach-omap1/mcbsp.c
ARM: includecheck fix: board-sffsdr.c
...
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s/head/held
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4A7BD37E.9060806@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
Make SCSI SG v4 driver enabled by default and remove EXPERIMENTAL dependency, since udev depends on BSG
block: Update topology documentation
block: Stack optimal I/O size
block: Add a wrapper for setting minimum request size without a queue
block: Make blk_queue_stack_limits use the new stacking interface
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* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (47 commits)
ehea: Fix napi list corruption on ifconfig down
igbvf: Allow VF driver to correctly recognize failure to set mac
3c59x: Fix build failure with gcc 3.2
sky2: Avoid transmits during sky2_down()
iwlagn: do not send key clear commands when rfkill enabled
libertas: Read buffer overflow
drivers/net/wireless: introduce missing kfree
drivers/net/wireless/iwlwifi: introduce missing kfree
zd1211rw: fix unaligned access in zd_mac_rx
cfg80211: fix regression on beacon world roaming feature
cfg80211: add two missing NULL pointer checks
ixgbe: Patch to modify 82598 PCIe completion timeout values
bluetooth: rfcomm_init bug fix
mlx4_en: Fix double pci unmapping.
mISDN: Fix handling of receive buffer size in L1oIP
pcnet32: VLB support fixes
pcnet32: remove superfluous NULL pointer check in pcnet32_probe1()
net: restore the original spinlock to protect unicast list
netxen: fix coherent dma mask setting
mISDN: Read buffer overflow
...
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The standard ACPI dock driver can handle the hotplug bays and docks of
the ThinkPads just fine (including batteries) as of 2.6.27, and the
code in thinkpad-acpi for the dock and bay subdrivers is currently
broken anyway...
Userspace needs some love to support the two-stage ejection nicely,
but it is simple enough to do through udev rules (you don't even need
HAL) so this wouldn't justify fixing the dock and bay subdrivers,
either.
That leaves warm-swap bays (_EJ3) support for thinkpad-acpi, as well
as support for the weird dock of the model 570, but since such support
has never left the "experimental" stage, it is also not a strong
enough reason to find a way to fix this code.
Users of ThinkPads with warm-swap bays are urged to request that _EJ3
support be added to the regular ACPI dock driver, if such feature is
indeed useful for them.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
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Update topology comments and sysfs documentation based upon discussions
with Neil Brown.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Use the %pI4 format string instead of %d.%d.%d.%d and NIPQUAD.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Augment the memory.txt file for ARM to list the cache aliasing
region ffff4000-fffffff.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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