During testing of a patch to stop having the perf subsytem
swallow nmis, it was uncovered that Nehalem boxes were randomly
getting unknown nmis when using the perf tool.

Moving the ack'ing of the PMI closer to when we get the status
allows the hardware to properly re-set the PMU bit signaling
another PMI was triggered during the processing of the first
PMI.  This allows the new logic for dealing with the
shortcomings of multiple PMIs to handle the extra NMI by
'eat'ing it later.

Now one can wonder why are we getting a second PMI when we
disable all the PMUs in the begining of the NMI handler to
prevent such a case, for that I do not know.  But I know the fix
below helps deal with this quirk.

Tested on multiple Nehalems where the problem was occuring.
With the patch, the code now loops a second time to handle the
second PMI (whereas before it was not).
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: peterz@infradead.org
Cc: robert.richter@amd.com
Cc: gorcunov@gmail.com
Cc: fweisbec@gmail.com
Cc: ying.huang@intel.com
Cc: ming.m.lin@intel.com
Cc: eranian@google.com
LKML-Reference: <1283454469-1909-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Merge branch 'urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile into perf/urgent

The use of the return value of init_sysfs() with commit

 10f0412f oprofile, x86: fix init_sysfs error handling

discovered the following build error for !CONFIG_PM:

 .../linux/arch/x86/oprofile/nmi_int.c: In function ‘op_nmi_init’:
 .../linux/arch/x86/oprofile/nmi_int.c:784: error: expected expression before ‘do’
 make[2]: *** [arch/x86/oprofile/nmi_int.o] Error 1
 make[1]: *** [arch/x86/oprofile] Error 2

This patch fixes this.
Reported-by: NIngo Molnar <mingo@elte.hu>
Cc: stable@kernel.org
Signed-off-by: NRobert Richter <robert.richter@amd.com>

During my rewrite, the semantics of touch_nmi_watchdog and
touch_softlockup_watchdog changed enough to break some drivers
(mostly over preemptable regions).

These are cases where long delays on one CPU (due to
print_delay for example) can cause long delays on other
CPUs - so we must 'touch' the nmi_watchdog flag of those
other CPUs as well.

This change brings those touch_*_watchdog() functions back in line
with to how they used to work.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Acked-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: peterz@infradead.org
Cc: fweisbec@gmail.com
LKML-Reference: <1283310009-22168-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

While we are reading trace_stat/functionX and someone just
disabled function_profile at that time, we can trigger this:

	divide error: 0000 [#1] PREEMPT SMP
	...
	EIP is at function_stat_show+0x90/0x230
	...

This fix just takes the ftrace_profile_lock and checks if
rec->counter is 0. If it's 0, we know the profile buffer
has been reset.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: stable@kernel.org
LKML-Reference: <4C723644.4040708@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

On failure init_sysfs() might not properly free resources. The error
code of the function is not checked. And, when reinitializing the exit
function might be called twice. This patch fixes all this.

Cc: stable@kernel.org
Signed-off-by: NRobert Richter <robert.richter@amd.com>

Per-thread events with a cpu filter, i.e., cpu != -1, were not
reporting correct timings when the thread never ran on the
monitored cpu. The time enabled was reported as a negative
value.

This patch fixes the problem by updating tstamp_stopped,
tstamp_running in event_sched_out() for events with filters and
which are marked as INACTIVE.

The function group_sched_out() is modified to systematically
call into event_sched_out() to avoid duplicating the timing
adjustment code twice.

With the patch, I now get:

$ task_cpu -i -e unhalted_core_cycles,unhalted_core_cycles
noploop 2 noploop for 2 seconds
CPU0 0		   unhalted_core_cycles (ena=1,991,136,594, run=0)
CPU0 0		   unhalted_core_cycles (ena=1,991,136,594, run=0)

CPU1 0		   unhalted_core_cycles (ena=1,991,136,594, run=0)
CPU1 0		   unhalted_core_cycles (ena=1,991,136,594, run=0)

CPU2 0		   unhalted_core_cycles (ena=1,991,136,594, run=0)
CPU2 0		   unhalted_core_cycles (ena=1,991,136,594, run=0)

CPU3 4,747,990,931 unhalted_core_cycles (ena=1,991,136,594, run=1,991,136,594)
CPU3 4,747,990,931 unhalted_core_cycles (ena=1,991,136,594, run=1,991,136,594)
Signed-off-by: NStephane Eranian <eranian@gmail.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: davem@davemloft.net
Cc: fweisbec@gmail.com
Cc: perfmon2-devel@lists.sf.net
Cc: eranian@google.com
LKML-Reference: <4c76802d.aae9d80a.115d.70fe@mx.google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Each histogram entry has a callchain root that stores the
callchain samples. However we forgot to initialize the
tracking of children hits of these roots, which then got
random values on their creation.

The root children hits is multiplied by the minimum percentage
of hits provided by the user, and the result becomes the minimum
hits expected from children branches. If the random value due
to the uninitialization is big enough, then this minimum number
of hits can be huge and eventually filter every children branches.

The end result was invisible callchains. All we need to
fix this is to initialize the children hits of the root.
Reported-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: 2.6.32.x-2.6.35.y <stable@kernel.org>

If on Pentium4 CPUs the FORCE_OVF flag is set then an NMI happens
on every event, which can generate a flood of NMIs. Clear it.
Reported-by: NVince Weaver <vweaver1@eecs.utk.edu>
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

save_stack_trace() stores the instruction pointer, not the
function descriptor. On ppc64 the trace stack code currently
dereferences the instruction pointer and shows 8 bytes of
instructions in our backtraces:

 # cat /sys/kernel/debug/tracing/stack_trace
        Depth    Size   Location    (26 entries)
        -----    ----   --------
  0)     5424     112   0x6000000048000004
  1)     5312     160   0x60000000ebad01b0
  2)     5152     160   0x2c23000041c20030
  3)     4992     240   0x600000007c781b79
  4)     4752     160   0xe84100284800000c
  5)     4592     192   0x600000002fa30000
  6)     4400     256   0x7f1800347b7407e0
  7)     4144     208   0xe89f0108f87f0070
  8)     3936     272   0xe84100282fa30000

Since we aren't dealing with function descriptors, use %pS
instead of %pF to fix it:

 # cat /sys/kernel/debug/tracing/stack_trace
        Depth    Size   Location    (26 entries)
        -----    ----   --------
  0)     5424     112   ftrace_call+0x4/0x8
  1)     5312     160   .current_io_context+0x28/0x74
  2)     5152     160   .get_io_context+0x48/0xa0
  3)     4992     240   .cfq_set_request+0x94/0x4c4
  4)     4752     160   .elv_set_request+0x60/0x84
  5)     4592     192   .get_request+0x2d4/0x468
  6)     4400     256   .get_request_wait+0x7c/0x258
  7)     4144     208   .__make_request+0x49c/0x610
  8)     3936     272   .generic_make_request+0x390/0x434
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: rostedt@goodmis.org
Cc: fweisbec@gmail.com
LKML-Reference: <20100825013238.GE28360@kryten>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch fixes a crash during shutdown reported below. The crash is
caused by accessing already freed task structs. The fix changes the
order for registering and unregistering notifier callbacks.

All notifiers must be initialized before buffers start working. To
stop buffer synchronization we cancel all workqueues, unregister the
notifier callback and then flush all buffers. After all of this we
finally can free all tasks listed.

This should avoid accessing freed tasks.

On 22.07.10 01:14:40, Benjamin Herrenschmidt wrote:

> So the initial observation is a spinlock bad magic followed by a crash
> in the spinlock debug code:
>
> [ 1541.586531] BUG: spinlock bad magic on CPU#5, events/5/136
> [ 1541.597564] Unable to handle kernel paging request for data at address 0x6b6b6b6b6b6b6d03
>
> Backtrace looks like:
>
>       spin_bug+0x74/0xd4
>       ._raw_spin_lock+0x48/0x184
>       ._spin_lock+0x10/0x24
>       .get_task_mm+0x28/0x8c
>       .sync_buffer+0x1b4/0x598
>       .wq_sync_buffer+0xa0/0xdc
>       .worker_thread+0x1d8/0x2a8
>       .kthread+0xa8/0xb4
>       .kernel_thread+0x54/0x70
>
> So we are accessing a freed task struct in the work queue when
> processing the samples.
Reported-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: stable@kernel.org
Signed-off-by: NRobert Richter <robert.richter@amd.com>

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

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  watchdog: Don't throttle the watchdog
  tracing: Fix timer tracing

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:
  mutex: Improve the scalability of optimistic spinning

pa-risc and ia64 have stacks that grow upwards. Check that
they do not run into other mappings. By making VM_GROWSUP
0x0 on architectures that do not ever use it, we can avoid
some unpleasant #ifdefs in check_stack_guard_page().
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When converting this to the new wait_for macro I inverted the wait
condition, which causes all sorts of problems.  So correct it to fix
several failures caused by the bad wait (flickering, bad output
detection, tearing, etc.).
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Tested-by: NSitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
  [S390] fix tlb flushing vs. concurrent /proc accesses
  [S390] s390: fix build error (sys_execve)

We should pass the data to the data register.
Signed-off-by: NJianwei Yang <jianwei.yang@intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It looks like there is an off-by-one error in one of your changes to
drivers/staging/rar_register/rar_register.c:
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This build bug triggers:

 drivers/built-in.o: In function `mantis_exit':
 (.text+0x377413): undefined reference to `ir_input_unregister'
 drivers/built-in.o: In function `mantis_input_init':
 (.text+0x3774ff): undefined reference to `__ir_input_register'

If MANTIS_CORE is enabled but IR_CORE is not. Add the correct
dependency.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc64: Get rid of indirect p1275 PROM call buffer.
  sparc64: Fill a missing delay slot.
  sparc64: Make lock backoff really a NOP on UP builds.
  sparc64: simple microoptimizations for atomic functions
  sparc64: Make rwsems 64-bit.
  sparc64: Really fix atomic64_t interface types.

The tlb flushing code uses the mm_users field of the mm_struct to
decide if each page table entry needs to be flushed individually with
IPTE or if a global flush for the mm_struct is sufficient after all page
table updates have been done. The comment for mm_users says "How many
users with user space?" but the /proc code increases mm_users after it
found the process structure by pid without creating a new user process.
Which makes mm_users useless for the decision between the two tlb
flusing methods. The current code can be confused to not flush tlb
entries by a concurrent access to /proc files if e.g. a fork is in
progres. The solution for this problem is to make the tlb flushing
logic independent from the mm_users field.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

* git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (25 commits)
  powerpc: Fix config dependency problem with MPIC_U3_HT_IRQS
  via-pmu: Add compat_pmu_ioctl
  powerpc: Wire up fanotify_init, fanotify_mark, prlimit64 syscalls
  powerpc/pci: Fix checking for child bridges in PCI code.
  powerpc: Fix typo in uImage target
  powerpc: Initialise paca->kstack before early_setup_secondary
  powerpc: Fix bogus it_blocksize in VIO iommu code
  powerpc: Inline ppc64_runlatch_off
  powerpc: Correct smt_enabled=X boot option for > 2 threads per core
  powerpc: Silence xics_migrate_irqs_away() during cpu offline
  powerpc: Silence __cpu_up() under normal operation
  powerpc: Re-enable preemption before cpu_die()
  powerpc/pci: Drop unnecessary null test
  powerpc/powermac: Drop unnecessary null test
  powerpc/powermac: Drop unnecessary of_node_put
  powerpc/kdump: Stop all other CPUs before running crash handlers
  powerpc/mm: Fix vsid_scrample typo
  powerpc: Use is_32bit_task() helper to test 32 bit binary
  powerpc: Export memstart_addr and kernstart_addr on ppc64
  powerpc: Make rwsem use "long" type
  ...

fix this build error:
arch/s390/kernel/process.c:272: error: conflicting types for 'sys_execve'
arch/s390/kernel/entry.h:45: error: previous declaration of 'sys_execve' was here
make[1]: *** [arch/s390/kernel/process.o] Error 1
make: *** [arch/s390/kernel] Error 2

introduced by d7627467Signed-off-by: NSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6:
  Staging: sep: remove driver
  Staging: batman-adv: Don't write in not allocated packet_buff
  Staging: batman-adv: Don't use net_dev after dev_put
  Staging: batman-adv: Create batman_if only on register event
  Staging: batman-adv: fix own mac address detection
  Staging: batman-adv: always reply batman icmp packets with primary mac
  Staging: batman-adv: fix batman icmp originating from secondary interface
  Staging: batman-adv: unify orig_hash_lock spinlock handling to avoid deadlocks
  Staging: batman-adv: Fix merge of linus tree
  Staging: spectra: removes unused functions
  Staging: spectra: initializa lblk variable
  Staging: spectra: removes unused variable
  Staging: spectra: remove duplicate GLOB_VERSION definition
  Staging: spectra: don't use locked_ioctl, fix build
  Staging: use new REQ_FLUSH flag, fix build breakage
  Staging: spectra: removes q->prepare_flush_fn, fix build breakage

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
  68328serial: check return value of copy_*_user() instead of access_ok()
  synclink: add mutex_unlock() on error path
  rocket: add a mutex_unlock()
  ip2: return -EFAULT on copy_to_user errors
  ip2: remove unneeded NULL check
  serial: print early console device address in hex

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6:
  kobject_uevent: fix typo in comments
  firmware_class: fix typo in error path
  kobject: Break the kobject namespace defs into their own header

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (29 commits)
  ARM: imx: fix build failure concerning otg/ulpi
  USB: ftdi_sio: add product ID for Lenz LI-USB
  USB: adutux: fix misuse of return value of copy_to_user()
  USB: iowarrior: fix misuse of return value of copy_to_user()
  USB: xHCI: update ring dequeue pointer when process missed tds
  USB: xhci: Remove buggy assignment in next_trb()
  USB: ftdi_sio: Add ID for Ionics PlugComputer
  USB: serial: io_ti.c: don't return 0 if writing the download record failed
  USB: otg: twl4030: fix wrong assumption of starting state
  USB: gadget: Return -ENOMEM on memory allocation failure
  USB: gadget: fix composite kernel-doc warnings
  USB: ssu100: set tty_flags in ssu100_process_packet
  USB: ssu100: add disconnect function for ssu100
  USB: serial: export symbol usb_serial_generic_disconnect
  USB: ssu100: rework logic for TIOCMIWAIT
  USB: ssu100: add register parameter to ssu100_setregister
  USB: ssu100: remove duplicate #defines in ssu100
  USB: ssu100: refine process_packet in ssu100
  USB: ssu100: add locking for port private data in ssu100
  USB: r8a66597-udc: return -ENOMEM if kzalloc() fails
  ...

This is based upon a report by Meelis Roos showing that it's possible
that we'll try to fetch a property that is 32K in size with some
devices.  With the current fixed 3K buffer we use for moving data in
and out of the firmware during PROM calls, that simply won't work.

In fact, it will scramble random kernel data during bootup.

The reasoning behind the temporary buffer is entirely historical.  It
used to be the case that we had problems referencing dynamic kernel
memory (including the stack) early in the boot process before we
explicitly told the firwmare to switch us over to the kernel trap
table.

So what we did was always give the firmware buffers that were locked
into the main kernel image.

But we no longer have problems like that, so get rid of all of this
indirect bounce buffering.

Besides fixing Meelis's bug, this also makes the kernel data about 3K
smaller.

It was also discovered during these conversions that the
implementation of prom_retain() was completely wrong, so that was
fixed here as well.  Currently that interface is not in use.
Reported-by: NMeelis Roos <mroos@linux.ee>
Tested-by: NMeelis Roos <mroos@linux.ee>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

MPIC_U3_HT_IRQS is selected both by PPC_PMAC64 and PPC_MAPLE, but depends
on PPC_MAPLE, so a PPC_PMAC64-only config gets this warning:

warning: (PPC_PMAC64 && PPC_PMAC && POWER4 || PPC_MAPLE && PPC64 && PPC_BOOK3S) selects MPIC_U3_HT_IRQS which has unmet direct dependencies (PPC_MAPLE)

Fix that by removing the dependency on PPC_MAPLE.
Signed-off-by: NAndreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The ioctls are actually compatible, but due to historical mistake the
numbers differ between 32bit and 64bit.
Signed-off-by: NAndreas Schwab <schwab@linux-m68k.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: NAndreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

pci_device_to_OF_node() can return null, and list_for_each_entry will
never enter the loop when dev is NULL, so it looks like this test is
a typo.
Reported-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit e32e78c5
(powerpc: fix build with make 3.82) introduced a
typo in uImage target and broke building uImage:

make: *** No rule to make target `uImage'.  Stop.
Signed-off-by: NAnatolij Gustschin <agust@denx.de>
Cc: stable <stable@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

As early setup calls down to slb_initialize(), we must have kstack
initialised before checking "should we add a bolted SLB entry for our kstack?"

Failing to do so means stack access requires an SLB miss exception to refill
an entry dynamically, if the stack isn't accessible via SLB(0) (kernel text
& static data).  It's not always allowable to take such a miss, and
intermittent crashes will result.

Primary CPUs don't have this issue; an SLB entry is not bolted for their
stack anyway (as that lives within SLB(0)).  This patch therefore only
affects the init of secondaries.
Signed-off-by: NMatt Evans <matt@ozlabs.org>
Cc: stable <stable@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

When looking at some issues with the virtual ethernet driver I noticed
that TCE allocation was following a very strange pattern:

address 00e9000 length 2048
address 0409000 length 2048 <-----
address 0429000 length 2048
address 0449000 length 2048
address 0469000 length 2048
address 0489000 length 2048
address 04a9000 length 2048
address 04c9000 length 2048
address 04e9000 length 2048
address 4009000 length 2048 <-----
address 4029000 length 2048

Huge unexplained gaps in what should be an empty TCE table. It turns out
it_blocksize, the amount we want to align the next allocation to, was
c0000000fe903b20. Completely bogus.

Initialise it to something reasonable in the VIO IOMMU code, and use kzalloc
everywhere to protect against this when we next add a non compulsary
field to iommu code and forget to initialise it.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

I'm sick of seeing ppc64_runlatch_off in our profiles, so inline it
into the callers. To avoid a mess of circular includes I didn't add
it as an inline function.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Acked-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The 'smt_enabled=X' boot option does not handle values of X > 2.
For Power 7 processors with smt modes of 0,1,2,3, and 4 this does
not work.  This patch allows the smt_enabled option to be set to
any value limited to a max equal to the number of threads per
core.
Signed-off-by: NNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

All IRQs are migrated away from a CPU that is being offlined so the
following messages suggest a problem when the system is behaving as
designed:

IRQ 262 affinity broken off cpu 1
IRQ 17 affinity broken off cpu 0
IRQ 18 affinity broken off cpu 0
IRQ 19 affinity broken off cpu 0
IRQ 256 affinity broken off cpu 0
IRQ 261 affinity broken off cpu 0
IRQ 262 affinity broken off cpu 0

Don't print these messages when the CPU is not online.
Signed-off-by: NDarren Hart <dvhltc@us.ibm.com>
Acked-by: NWill Schmidt <will_schmidt@vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nathan Fontenot <nfont@austin.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

During CPU offline/online tests __cpu_up would flood the logs with
the following message:

Processor 0 found.

This provides no useful information to the user as there is no context
provided, and since the operation was a success (to this point) it is expected
that the CPU will come back online, providing all the feedback necessary.

Change the "Processor found" message to DBG() similar to other such messages in
the same function. Also, add an appropriate log level for the "Processor is
stuck" message.
Signed-off-by: NDarren Hart <dvhltc@us.ibm.com>
Acked-by: NWill Schmidt <will_schmidt@vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nathan Fontenot <nfont@austin.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

start_secondary() is called shortly after _start and also via

cpu_idle()->cpu_die()->pseries_mach_cpu_die()

start_secondary() expects a preempt_count() of 0. pseries_mach_cpu_die() is
called via the cpu_idle() routine with preemption disabled, resulting in the
following repeating message during rapid cpu offline/online tests
with CONFIG_PREEMPT=y:

BUG: scheduling while atomic: swapper/0/0x00000002
Modules linked in: autofs4 binfmt_misc dm_mirror dm_region_hash dm_log [last unloaded: scsi_wait_scan]
Call Trace:
[c00000010e7079c0] [c0000000000133ec] .show_stack+0xd8/0x218 (unreliable)
[c00000010e707aa0] [c0000000006a47f0] .dump_stack+0x28/0x3c
[c00000010e707b20] [c00000000006e7a4] .__schedule_bug+0x7c/0x9c
[c00000010e707bb0] [c000000000699d9c] .schedule+0x104/0x800
[c00000010e707cd0] [c000000000015b24] .cpu_idle+0x1c4/0x1d8
[c00000010e707d70] [c0000000006aa1b4] .start_secondary+0x398/0x3d4
[c00000010e707e30] [c000000000008278] .start_secondary_resume+0x10/0x14

Move the cpu_die() call inside the existing preemption enabled block of
cpu_idle(). This is safe as the idle task is affined to a single CPU so the
debug_smp_processor_id() tests (from cpu_should_die()) won't trigger as we are
in a "migration disabled" region.
Signed-off-by: NDarren Hart <dvhltc@us.ibm.com>
Acked-by: NWill Schmidt <will_schmidt@vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nathan Fontenot <nfont@austin.ibm.com>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>