Kthreads that have called kthread_bind() are bound to specific cpus, so
other tasks should not be able to change their cpus_allowed from under
them.  Otherwise, it is possible to move kthreads, such as the migration
or software watchdog threads, so they are not allowed access to the cpu
they work on.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Cliff Wickman wrote:

> I built an ia64 kernel from Andrew's tree (2.6.26-rc2-mm1)
> and get a very predictable hotplug cpu problem.
> billberry1:/tmp/cpw # ./dis
> disabled cpu 17
> enabled cpu 17
> billberry1:/tmp/cpw # ./dis
> disabled cpu 17
> enabled cpu 17
> billberry1:/tmp/cpw # ./dis
>
> The script that disables the cpu always hangs (unkillable)
> on the 3rd attempt.
>
> And a bit further:
> The kstopmachine thread always sits on the run queue (real time) for about
> 30 minutes before running.

this fix solves some (but not all) issues between CPU hotplug and
RT bandwidth throttling.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

weighted_cpuload is only used on SMP. move it into the CONFIG_SMP
section.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

kernel/cpu.c seems a more logical place for those maps since they do not really
have much to do with the scheduler these days.

kernel/cpu.c is now built for the UP kernel too, but it does not affect the size
the kernel sections.

$ size vmlinux

before
   text       data        bss        dec        hex    filename
3313797     307060     310352    3931209     3bfc49    vmlinux

after
   text       data        bss        dec        hex    filename
3313797     307060     310352    3931209     3bfc49    vmlinux
Signed-off-by: NMax Krasnyansky <maxk@qualcomm.com>
Cc: pj@sgi.com
Cc: menage@google.com
Cc: rostedt@goodmis.org
Cc: mingo@elte.hu
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

First issue is not related to the cpusets. We're simply leaking doms_cur.
It's allocated in arch_init_sched_domains() which is called for every
hotplug event. So we just keep reallocation doms_cur without freeing it.
I introduced free_sched_domains() function that cleans things up.

Second issue is that sched domains created by the cpusets are
completely destroyed by the CPU hotplug events. For all CPU hotplug
events scheduler attaches all CPUs to the NULL domain and then puts
them all into the single domain thereby destroying domains created
by the cpusets (partition_sched_domains).
The solution is simple, when cpusets are enabled scheduler should not
create default domain and instead let cpusets do that. Which is
exactly what the patch does.
Signed-off-by: NMax Krasnyansky <maxk@qualcomm.com>
Cc: pj@sgi.com
Cc: menage@google.com
Cc: rostedt@goodmis.org
Cc: mingo@elte.hu
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

this patch was not built on !SMP:

 kernel/sched_rt.c: In function 'inc_rt_tasks':
 kernel/sched_rt.c:404: error: 'struct rq' has no member named 'online'
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Peter pointed out that the last version of the "fix" was still one off
under certain circumstances. Use BITS_TO_LONG instead to get an
accurate result.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

A rounding error was pointed out by Peter Zijlstra which would result
in the structure holding priorities to be off by one.
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The RT folks over at RedHat found an issue w.r.t. hotplug support which
was traced to problems with the cpupri infrastructure in the scheduler:

https://bugzilla.redhat.com/show_bug.cgi?id=449676

This bug affects 23-rt12+, 24-rtX, 25-rtX, and sched-devel.  This patch
applies to 25.4-rt4, though it should trivially apply to most cpupri enabled
kernels mentioned above.

It turned out that the issue was that offline cpus could get inadvertently
registered with cpupri so that they were erroneously selected during
migration decisions.  The end result would be an OOPS as the offline cpu
had tasks routed to it.

This patch generalizes the old join/leave domain interface into an
online/offline interface, and adjusts the root-domain/hotplug code to
utilize it.

I was able to easily reproduce the issue prior to this patch, and am no
longer able to reproduce it after this patch.  I can offline cpus
indefinately and everything seems to be in working order.

Thanks to Arnaldo (acme), Thomas, and Peter for doing the legwork to point
me in the right direction.  Also thank you to Peter for reviewing the
early iterations of this patch.
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

While printing out the visual representation of the sched-domains, print
the level (MC, SMT, CPU, NODE, ... ) of each of the sched_domains.

Credit: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

SCHED_DOMAIN_DEBUG mentioned in the Documentation for sched-domains
for enabling sched-domains debugging doesn't exist anymore.

Update the documentation to reflect the correct way of enabling
sched-domain debugging.
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

make sched.c easier to read.
Signed-off-by: NDhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

For the normal WARN_ON() etc we added a print-the-modules-list already,
which is very useful to figure out candidates for certain types of bugs.

This patch adds the same print to the "scheduling while atomic" BUG warning,
for the same reason: when we get here it's very useful to see which modules
are loaded, to narrow down the candidate code list.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: mingo@elte.hu
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch removes 24 bytes of padding and allows 1 extra object per
slab on my fedora based config.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Fix this warning, which appears with !CONFIG_SMP:
kernel/sched.c:1216: warning: `init_hrtick' defined but not used
Signed-off-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

[ Stephen Rothwell <sfr@canb.auug.org.au>: build fix ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Nothing really serious here, mainly just a matter of nit-picking :-/

From: Dmitry Adamushko <dmitry.adamushko@gmail.com>
For CONFIG_SCHED_DEBUG && CONFIG_SYSCT configs, sd->flags can be altered
while being manipulated in rebalance_domains(). Let's do an atomic check.
We rely here on the atomicity of read/write accesses for aligned words.
Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The currently logic inadvertently skips the last task on the run-queue,
resulting in missed balance opportunities.
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
Signed-off-by: NDavid Bahi <dbahi@novell.com>
CC: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The current code use a linear algorithm which causes scaling issues
on larger SMP machines.  This patch replaces that algorithm with a
2-dimensional bitmap to reduce latencies in the wake-up path.
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

it is safe to ignore timers and flags when the feature is disabled.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Dmitry Adamushko pointed out a known flaw in the rt-balancing algorithm
that could allow suboptimal balancing if a non-migratable task gets
queued behind a running migratable one.  It is discussed in this thread:

http://lkml.org/lkml/2008/4/22/296

This issue has been further exacerbated by a recent checkin to
sched-devel (git-id 5eee63a5ebc19a870ac40055c0be49457f3a89a3).

>From a pure priority standpoint, the run-queue is doing the "right"
thing. Using Dmitry's nomenclature, if T0 is on cpu1 first, and T1
wakes up at equal or lower priority (affined only to cpu1) later, it
*should* wait for T0 to finish.  However, in reality that is likely
suboptimal from a system perspective if there are other cores that
could allow T0 and T1 to run concurrently.  Since T1 can not migrate,
the only choice for higher concurrency is to try to move T0.  This is
not something we addessed in the recent rt-balancing re-work.

This patch tries to enhance the balancing algorithm by accomodating this
scenario.  It accomplishes this by incorporating the migratability of a
task into its priority calculation.  Within a numerical tsk->prio, a
non-migratable task is logically higher than a migratable one.  We
maintain this by introducing a new per-priority queue (xqueue, or
exclusive-queue) for holding non-migratable tasks.  The scheduler will
draw from the xqueue over the standard shared-queue (squeue) when
available.

There are several details for utilizing this properly.

1) During task-wake-up, we not only need to check if the priority
   preempts the current task, but we also need to check for this
   non-migratable condition.  Therefore, if a non-migratable task wakes
   up and sees an equal priority migratable task already running, it
   will attempt to preempt it *if* there is a likelyhood that the
   current task will find an immediate home.

2) Tasks only get this non-migratable "priority boost" on wake-up.  Any
   requeuing will result in the non-migratable task being queued to the
   end of the shared queue.  This is an attempt to prevent the system
   from being completely unfair to migratable tasks during things like
   SCHED_RR timeslicing.

I am sure this patch introduces potentially "odd" behavior if you
concoct a scenario where a bunch of non-migratable threads could starve
migratable ones given the right pattern.  I am not yet convinced that
this is a problem since we are talking about tasks of equal RT priority
anyway, and there never is much in the way of guarantees against
starvation under that scenario anyway. (e.g. you could come up with a
similar scenario with a specific timing environment verses an affinity
environment).  I can be convinced otherwise, but for now I think this is
"ok".
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
CC: Dmitry Adamushko <dmitry.adamushko@gmail.com>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

* master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] pxa: fix tosa.c build error
  [ARM] 5067/1: _raw_write_can_lock macro bugfix
  [ARM] 5070/1: pxa: add GPIO104_PSKTSEL to pxa27x MFP configuration
  [ARM] 5068/1: PXA2xx Additional gpio definitions
  [ARM] 5066/2: EM-X270: Fix DM9000 IRQ flags initialisation
  [ARM] 5065/2: CM-X270: Fix DM9000 IRQ flags initialisation
  [ARM] 5062/1: pxa: remove unused definition of CONFIG_ARCH_COTULLA_IDP
  [ARM] 5060/1: remove unnecessary include of asm/io.h
  [ARM] fix AT91 include loops

Fairly simple. "dev_use" was being allocated as a zero length array
because of bad math on 64-bit systems, causing a crash in
find_first_zero_bit(). One-liner follows:
Signed-off-by: NBen Collins <ben.collins@canonical.com>
Acked-by: NPierre Ossman <drzeus@drzeus.cx>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (48 commits)
  V4L/DVB (8001): dib0070: fix dib0070_attach when !CONFIG_DVB_TUNER_DIB0070
  V4L/DVB (8000): tda827x: fix NULL pointer in tda827xa_lna_gain
  V4L/DVB (7990): Fix entry for PowerColor RA 330 and make it run with firmware version 2.7
  V4L/DVB (7983): tda18271_calc_rf_cal must return the return value of tda18271_lookup_map
  V4L/DVB (7978): cx18: explicitly test for XC2028 tuner
  V4L/DVB (7977): cx18: fix init order and remove duplicate open_on_first_use.
  V4L/DVB (7975): saa7134_empress
  V4L/DVB (7974): fix MEDIA_TUNER && FW_LOADER build error
  V4L/DVB (7972): or51132.c: unaligned
  V4L/DVB (7971): usb: unaligned
  V4L/DVB (7970): mix trivial endianness annotations
  V4L/DVB (7969): m920x: unaligned access
  V4L/DVB (7968): zoran: endianness annotations
  V4L/DVB (7967): bt8xx: unaligned access
  V4L/DVB (7966): cx18: direct dereferencing of iomem
  V4L/DVB (7965): annotate bcx_riscmem
  V4L/DVB (7964): cx18 iomem annotations
  V4L/DVB (7963): ivtv: trivial annotations
  V4L/DVB (7962): ttusb endianness annotations and fixes
  V4L/DVB (7961): fix endianness bug in dib0700_devices.c
  ...

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  Fix divide by zero error in build_clear_page() and build_copy_page()
  [MIPS] Fix typo in header guard
  [MIPS] Fix build error - Delete debugging crap that crept in with CMP
  [MIPS] Add accessors for random register.
  [MIPS] IP27: misc fixes
  [MIPS] IP27: Fix clockevent setup
  [MIPS] IP27: Fix bootmem memory setup
  [MIPS] remove CONFIG_CPU_R4000 line from Makefile
  [MIPS] Fix check for valid stack pointer during backtrace
  [MIPS] Add missing braces to pte_mkyoung
  [MIPS] R4700: Fix build_tlb_probe_entry
  [MIPS] Alchemy: dbdma: add API to delete custom DDMA device ids.
  [MIPS] Alchemy: export get_au1x00_speed for modules

* git://git.infradead.org/~dwmw2/mtd-2.6.26:
  [MTD] [MAPS] Fix cmdlineparse handling in mapping files
  [MTD] [NAND] pxa: fix incorrect calling of pxa3xx_nand_config() on resume path

Suggest how to deal with patch modifications caused by
merging or back-porting when you're a maintainer.
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Don't trust a length which is greater than the working buffer.
  An invalid length could cause overflow when calculating buffer size
  for decoding oid.

- An oid length of zero is invalid and allows for an off-by-one error when
  decoding oid because the first subid actually encodes first 2 subids.

- A primitive encoding may not have an indefinite length.

Thanks to Wei Wang from McAfee for report.

Cc: Steven French <sfrench@us.ibm.com>
Cc: stable@kernel.org
Acked-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NChris Wright <chrisw@sous-sol.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Alias brd to rd in the hope of helping legacy users. Suggested by Jan.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Here is an attempt to translate the prompt and help text into something
which is legible and, as a bonus, correct.
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ip_fast_csum() requires a memory clobber on its inline asm as it accesses
memory in a fashion that gcc can't predict.

The GCC manual says:

 If your assembler instructions access memory in an unpredictable
 fashion, add `memory' to the list of clobbered registers.  This will
 cause GCC to not keep memory values cached in registers across the
 assembler instruction and not optimize stores or loads to that memory.

The bug hasn't been noticed in FRV, but it has been seen in PA-RISC.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We don't need to reserve "unset" resources.  Trying to reserve
them results in messages like this, which are ugly but harmless:

    system 00:08: iomem range 0x0-0x0 could not be reserved

Future PNP patches will remove use of IORESOURCE_UNSET, but
we still need it for now.
Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NYoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

- fix PCI interrupt assignment by emulating ioc3 interrupt pin register
- use pci_probe_only mode
- select correct page size in bridge
- remove no longer needed ioc3_sio_init() code

[Ralf: Fix for 64kB or larger pagesizes]
Signed-off-by: NThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Fix breakage introduced by converting hub_rt to clockevent.
Signed-off-by: NThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Changes in the generic bootmem code broke memory setup for IP27. This
patch fixes this by replacing lots of special IP27 code with generic
bootmon code. This has been tested only on a single node.
Signed-off-by: NThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>