Impact: fix possible deadlock in CPU hot-remove path

This patch fixes a possible deadlock scenario in the CPU remove path.
migration_call grabs rq->lock, then wakes up everything on rq->migration_queue
with the lock held. Then one of the tasks on the migration queue ends up
calling tg_shares_up which then also tries to acquire the same rq->lock.

[c000000058eab2e0] c000000000502078 ._spin_lock_irqsave+0x98/0xf0
[c000000058eab370] c00000000008011c .tg_shares_up+0x10c/0x20c
[c000000058eab430] c00000000007867c .walk_tg_tree+0xc4/0xfc
[c000000058eab4d0] c0000000000840c8 .try_to_wake_up+0xb0/0x3c4
[c000000058eab590] c0000000000799a0 .__wake_up_common+0x6c/0xe0
[c000000058eab640] c00000000007ada4 .complete+0x54/0x80
[c000000058eab6e0] c000000000509fa8 .migration_call+0x5fc/0x6f8
[c000000058eab7c0] c000000000504074 .notifier_call_chain+0x68/0xe0
[c000000058eab860] c000000000506568 ._cpu_down+0x2b0/0x3f4
[c000000058eaba60] c000000000506750 .cpu_down+0xa4/0x108
[c000000058eabb10] c000000000507e54 .store_online+0x44/0xa8
[c000000058eabba0] c000000000396260 .sysdev_store+0x3c/0x50
[c000000058eabc10] c0000000001a39b8 .sysfs_write_file+0x124/0x18c
[c000000058eabcd0] c00000000013061c .vfs_write+0xd0/0x1bc
[c000000058eabd70] c0000000001308a4 .sys_write+0x68/0x114
[c000000058eabe30] c0000000000086b4 syscall_exit+0x0/0x40
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: do not expose a control that has no effect

Fix to prevent sched_mc_power_saving from being exported through sysfs
on single-socket systems. (Say multicore single socket (Laptop))

CPU core map of the boot cpu should be equal to possible number
of cpus for single socket system.

This fix has been developed at FOSS.in kernel workout.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
  drm/i915: Fix copy'n'pasteo that broke VT switch if flushing was non-empty.

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
  powerpc: Fix system calls on Cell entered with XER.SO=1
  powerpc/cell: Fix GDB watchpoints, again
  powerpc/mpic: Don't reset affinity for secondary MPIC on boot
  powerpc/cell/axon-msi: Retry on missing interrupt
  powerpc: Fix boot freeze on machine with empty memory node
  powerpc: Fix IRQ assignment for some PCIe devices
  powerpc/spufs: Fix spinning in spufs_ps_fault on signal
  powerpc/mpc832x_rdb: fix swapped ethernet ids
  powerpc: Use generic PHY driver for Marvell 88E1111 PHY on GE Fanuc SBC610
  powerpc/85xx: L2 cache size wrong in 8572DS dts
  powerpc/virtex: Update defconfigs
  powerpc/52xx: update defconfigs
  xsysace: Fix driver to use resource_size_t instead of unsigned long
  powerpc/virtex: fix various format/casting printk mismatches
  powerpc/mpc5200: fix bestcomm Kconfig dependencies
  powerpc/44x: Fix 460EX/460GT machine check handling
  powerpc/40x: Limit allocable DRAM during early mapping

* master.kernel.org:/home/rmk/linux-2.6-arm:
  Allow architectures to override copy_user_highpage()
  [ARM] pxa/palmtx: misc fixes to use generic GPIO API
  ARM: OMAP: Fixes for suspend / resume GPIO wake-up handling
  [ARM] pxa/corgi: update default config to exclude tosa from being built
  [ARM] pxa/pcm990: use negative number for an invalid GPIO in camera data
  ARM: OMAP: Typo fix for clock_allow_idle
  ARM: OMAP: Remove broken LCD driver for SX1
  [ARM] 5335/1: pxa25x_udc: Fix is_vbus_present to return 1 or 0
  [ARM] pxa/MioA701: bluetooth resume fix
  [ARM] pxa/MioA701: fix memory corruption.

Introduced in the "Avoid BUG_ONs on VT switch" commit.
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

It turns out that on Cell, on a kernel with CONFIG_VIRT_CPU_ACCOUNTING
= y, if a program sets the SO (summary overflow) bit in the XER and
then does a system call, the SO bit in CR0 will be set on return
regardless of whether the system call detected an error.  Since CR0.SO
is used as the error indication from the system call, this means that
all system calls appear to fail.

The reason is that the workaround for the timebase bug on Cell uses a
compare instruction.  With CONFIG_VIRT_CPU_ACCOUNTING = y, the
ACCOUNT_CPU_USER_ENTRY macro reads the timebase, so we end up doing a
compare instruction, which copies XER.SO to CR0.SO.  Since we were
doing this in the system call entry patch after clearing CR0.SO but
before saving the CR, this meant that the saved CR image had CR0.SO
set if XER.SO was set on entry.

This fixes it by moving the clearing of CR0.SO to after the
ACCOUNT_CPU_USER_ENTRY call in the system call entry path.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

An earlier patch from Jens Osterkamp attempted to fix GDB
watchpoints by enabling the DABRX register at boot time.
Unfortunately, this did not work on SMP setups, where
secondary CPUs were still using the power-on DABRX value.

This introduces the same change for secondary CPUs on cell
as well.
Reported-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Tested-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

Kexec/kdump currently fails on the IBM QS2x blades when the kexec happens
on a CPU other than the initial boot CPU.  It turns out that this is the
result of mpic_init trying to set affinity of each interrupt vector to the
current boot CPU.

As far as I can tell,  the same problem is likely to exist on any
secondary MPIC, because they have to deliver interrupts to the first
output all the time. There are two potential solutions for this: either
not set up affinity at all for secondary MPICs, or assume that a single
CPU output is connected to the upstream interrupt controller and hardcode
affinity to that per architecture.

This patch implements the second approach, defaulting to the first output.
Currently, all known secondary MPICs are routed to their upstream port
using the first destination, so we hardcode that.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

The MSI capture logic for the axon bridge can sometimes
lose interrupts in case of high DMA and interrupt load,
when it signals an MSI interrupt to the MPIC interrupt
controller while we are already handling another MSI.

Each MSI vector gets written into a FIFO buffer in main
memory using DMA, and that DMA access is normally flushed
by the actual interrupt packet on the IOIF.  An MMIO
register in the MSIC holds the position of the last
entry in the FIFO buffer that was written.  However,
reading that position does not flush the DMA, so that
we can observe stale data in the buffer.

In a stress test, we have observed the DMA to arrive
up to 14 microseconds after reading the register.

This patch works around this problem by retrying the
access to the FIFO buffer.

We can reliably detect the conditioning by writing
an invalid MSI vector into the FIFO buffer after
reading from it, assuming that all MSIs we get
are valid.  After detecting an invalid MSI vector,
we udelay(1) in the interrupt cascade for up to
100 times before giving up.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

I got a bug report about a distro kernel not booting on a particular
machine.  It would freeze during boot:

> ...
> Could not find start_pfn for node 1
> [boot]0015 Setup Done
> Built 2 zonelists in Node order, mobility grouping on.  Total pages: 123783
> Policy zone: DMA
> Kernel command line:
> [boot]0020 XICS Init
> [boot]0021 XICS Done
> PID hash table entries: 4096 (order: 12, 32768 bytes)
> clocksource: timebase mult[7d0000] shift[22] registered
> Console: colour dummy device 80x25
> console handover: boot [udbg0] -> real [hvc0]
> Dentry cache hash table entries: 1048576 (order: 7, 8388608 bytes)
> Inode-cache hash table entries: 524288 (order: 6, 4194304 bytes)
> freeing bootmem node 0

I've reproduced this on 2.6.27.7.  It is caused by commit
8f64e1f2 ("powerpc: Reserve in bootmem
lmb reserved regions that cross NUMA nodes").

The problem is that Jon took a loop which was (in pseudocode):

	for_each_node(nid)
		NODE_DATA(nid) = careful_alloc(nid);
		setup_bootmem(nid);
		reserve_node_bootmem(nid);

and broke it up into:

	for_each_node(nid)
		NODE_DATA(nid) = careful_alloc(nid);
		setup_bootmem(nid);
	for_each_node(nid)
		reserve_node_bootmem(nid);

The issue comes in when the 'careful_alloc()' is called on a node with
no memory.  It falls back to using bootmem from a previously-initialized
node.  But, bootmem has not yet been reserved when Jon's patch is
applied.  It gives back bogus memory (0xc000000000000000) and pukes
later in boot.

The following patch collapses the loop back together.  It also breaks
the mark_reserved_regions_for_nid() code out into a function and adds
some comments.  I think a huge part of introducing this bug is because
for loop was too long and hard to read.

The actual bug fix here is the:

+		if (end_pfn <= node->node_start_pfn ||
+		    start_pfn >= node_end_pfn)
+			continue;
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

Currently, some PCIe devices on POWER6 machines do not get interrupts
assigned correctly.  The problem is that OF doesn't create an
"interrupt" property for them.  The fix is for of_irq_map_pci to fall
back to using the value in the PCI interrupt-pin register in config
space, as we do when there is no OF device-tree node for the device.

I have verified that this works fine with a pair of Squib-E SAS
adapter on a P6-570.
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
  parisc: struct device - replace bus_id with dev_name(), dev_set_name()
  parisc: fix kernel crash when unwinding a userspace process
  parisc: __kernel_time_t is always long

* git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6:
  [CIFS] fix regression in cifs_write_begin/cifs_write_end

Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: prevent divide by zero error in cpu_avg_load_per_task, update
  sched, cpusets: fix warning in kernel/cpuset.c
  sched: prevent divide by zero error in cpu_avg_load_per_task

Merge branch 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  irq.h: fix missing/extra kernel-doc
  genirq: __irq_set_trigger: change pr_warning to pr_debug
  irq: fix typo
  x86: apic honour irq affinity which was set in early boot
  genirq: fix the affinity setting in setup_irq
  genirq: keep affinities set from userspace across free/request_irq()

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  lockdep: consistent alignement for lockdep info

Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  ftrace: prevent recursion
  tracing, doc: update mmiotrace documentation
  x86, mmiotrace: fix buffer overrun detection
  function tracing: fix wrong position computing of stack_trace

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: always define DECLARE_PCI_UNMAP* macros
  x86: fixup config space size of CPU functions for AMD family 11h
  x86, bts: fix wrmsr and spinlock over kmalloc
  x86, pebs: fix PEBS record size configuration
  x86, bts: turn macro into static inline function
  x86, bts: exclude ds.c from build when disabled
  arch/x86/kernel/pci-calgary_64.c: change simple_strtol to simple_strtoul
  x86: use limited register constraint for setnz
  xen: pin correct PGD on suspend
  x86: revert irq number limitation
  x86: fixing __cpuinit/__init tangle, xsave_cntxt_init()
  x86: fix __cpuinit/__init tangle in init_thread_xstate()
  oprofile: fix an overflow in ppro code

* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
  drm/i915: Save/restore HWS_PGA on suspend/resume
  drm: move drm vblank initialization/cleanup to driver load/unload
  drm/i915: execbuffer pins objects, no need to ensure they're still in the GTT
  drm/i915: Always read pipestat in irq_handler
  drm/i915: Subtract total pinned bytes from available aperture size
  drm/i915: Avoid BUG_ONs on VT switch with a wedged chipset.
  drm/i915: Remove IMR masking during interrupt handler, and restart it if needed.
  drm/i915: Manage PIPESTAT to control vblank interrupts instead of IMR.

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6:
  udf: Fix BUG_ON() in destroy_inode()

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
  [CPUFREQ] powernow-k8: ignore out-of-range PstateStatus value
  [CPUFREQ] Documentation: Add Blackfin to list of supported processors

A very minor patch on ramfs-rootfs-initramfs.txt: update the location
where CONFIG_INITRAMFS_SOURCE lives in menuconfig
Signed-off-by: Frans Meulenbroeks <fransmeulenbroeks@gmail.com>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: hda - Check model for Dell 92HD73xx laptops
  ALSA: hda - mark Dell studio 1535 quirk
  ALSA: hda - No 'Headphone as Line-out' swich without line-outs
  ALSA: hda - Fix AFG power management on IDT 92HD* codecs
  ALSA: hda - Fix caching of SPDIF status bits
  ALSA: hda - Add a quirk for Dell Studio 15
  ALSA: hda: Add STAC_DELL_M4_3 quirk
  sound/sound_core: Fix sparse warnings
  ALSA: hda: STAC_DELL_M6 EAPD

* 'linux-next' of git://git.infradead.org/~dedekind/ubi-2.6:
  UBI: Don't exit from ubi_thread until kthread_should_stop() is true
  UBI: fix EBADMSG handling

* 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
  i2c-parport: Fix misplaced parport_release call
  i2c: Remove i2c clients in reverse order
  i2c/isp1301_omap: Build fixes

Compress a set of consecutive switch cases into a case-range.
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
  [S390] Update default configuration.
  [S390] Fix alignment of initial kernel stack.
  [S390] pgtable.h: Fix oops in unmap_vmas for KVM processes
  [S390] fix/cleanup sched_clock
  [S390] fix system call parameter functions.

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6:
  toshiba_acpi: close race in toshiba_acpi driver
  ACPICA: disable _BIF warning
  ACPI: delete OSI(Linux) DMI dmesg spam
  ACPICA: Allow _WAK method to return an Integer
  ACPI: thinkpad-acpi: fix fan sleep/resume path
  sony-laptop: printk tweak
  sony-laptop: brightness regression fix
  Revert "ACPI: don't enable control method power button as wakeup device when Fixed Power button is used"
  ACPI suspend: Blacklist boxes that require us to set SCI_EN directly on resume
  ACPI: scheduling in atomic via acpi_evaluate_integer ()
  ACPI: battery: Convert discharge energy rate to current properly
  ACPI: EC: count interrupts only if called from interrupt handler.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: wacom - add support for new USB Tablet PCs
  Input: replace spin_lock_bh with spin_lock_irqsave in ml_ff_playback
  Input: i8042 - add Compal Hel80 laptop to nomux blacklist
  Input: cm109 - add keymap for ATCom AU-100 phone
  Input: fix the example of an input device driver
  Input: psmouse - fix incorrect validate_byte check in OLPC protocol
  Input: atkbd - cancel delayed work before freeing its structure
  Input: atkbd - add keymap quirk for Inventec Symphony systems
  Input: i8042 - add Dell XPS M1530 to nomux list
  Input: elo - fix format string in elo driver

All architectures now use the generic compat_sys_ptrace, as should every
new architecture that needs 32bit compat (if we'll ever get another).

Remove the now superflous __ARCH_WANT_COMPAT_SYS_PTRACE define, and also
kill a comment about __ARCH_SYS_PTRACE that was added after
__ARCH_SYS_PTRACE was already gone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  MIPS: Make BUG() __noreturn.

ml_ff_playback() uses spin_(un)lock_bh. However this function is called
with interrupts disabled from erase_effect() in drivers/input/ff-core.c:196.

This is not permitted, and will result in a WARN_ON in the bottom half handling code.
This patch changes this function to just use spin_lock_irqsave() instead, solving
the problem and simplifying the locking logic.

This was reported as entry #106559 in kerneloops.org

Reported-by: kerneloops.org
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Same as for hotplug_cpu - we want static notifier_block in there in meminitdata,
to avoid false positives whenever it's used.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

called only from __init
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

... by giving the instances' names magic suffix recognized by modpost ;-/
Their ->probe() is __devinit
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

... so get xen-ops.h in agreement with xen/smp.c
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

calls __init, called only from __init
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>