Make text_poke_early available outside of alternative.c. The jump label
patchset wants to make use of it in order to set up the optimal no-op
sequences at run-time.
Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <04cfddf2ba77bcabfc3e524f1849d871d6a1cf9d.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Move Steve's code for finding the best 5-byte no-op from ftrace.c to
alternative.c. The idea is that other consumers (in this case jump label)
want to make use of that code.
Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <96259ae74172dcac99c0020c249743c523a92e18.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Remove __dummy_buf which is needed for kallsyms_lookup only.
use kallsysm_lookup_size_offset instead.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
LKML-Reference: <1284512670-2369-5-git-send-email-namhyung@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make following (internal) functions static to make sparse
happier :-)
* get_optimized_kprobe: only called from static functions
* kretprobe_table_unlock: _lock function is static
* kprobes_optinsn_template_holder: never called but holding asm code
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
LKML-Reference: <1284512670-2369-4-git-send-email-namhyung@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix a bug introduced with commit de725de and the change in the
meaning of the return value of intel_pmu_handle_irq(). With the
current code, when you are using the BTS, you get 'dazed by NMI'
each time the BTS buffer fills up.
BTS does interrupt on the PMU vector, thus NMI. You need to take
this into account in the return value of the function.
This version fixes initial patch which was missing changes to
perf_event_intel_ds.c.
Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: peterz@infradead.org
Cc: paulus@samba.org
Cc: davem@davemloft.net
Cc: fweisbec@gmail.com
Cc: perfmon2-devel@lists.sf.net
Cc: eranian@gmail.com
Cc: robert.richter@amd.com
LKML-Reference: <4c8a1686.aae9d80a.5aa4.5e35@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A real life genuine preemption leak..
Reported-and-tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: Perform hardware_enable in CPU_STARTING callback
KVM: i8259: fix migration
KVM: fix i8259 oops when no vcpus are online
KVM: x86 emulator: fix regression with cmpxchg8b on i386 hosts
Neither the overcommit nor the reservation sysfs parameter were
actually working, remove them as they'll only get in the way.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Replace pmu::{enable,disable,start,stop,unthrottle} with
pmu::{add,del,start,stop}, all of which take a flags argument.
The new interface extends the capability to stop a counter while
keeping it scheduled on the PMU. We replace the throttled state with
the generic stopped state.
This also allows us to efficiently stop/start counters over certain
code paths (like IRQ handlers).
It also allows scheduling a counter without it starting, allowing for
a generic frozen state (useful for rotating stopped counters).
The stopped state is implemented in two different ways, depending on
how the architecture implemented the throttled state:
1) We disable the counter:
a) the pmu has per-counter enable bits, we flip that
b) we program a NOP event, preserving the counter state
2) We store the counter state and ignore all read/overflow events
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since the current perf_disable() usage is only an optimization,
remove it for now. This eases the removal of the __weak
hw_perf_enable() interface.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Simple registration interface for struct pmu, this provides the
infrastructure for removing all the weak functions.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, mcheck: Avoid duplicate sysfs links/files for thresholding banks
io-mapping: Fix the address space annotations
x86: Fix the address space annotations of iomap_atomic_prot_pfn()
x86, mm: Fix CONFIG_VMSPLIT_1G and 2G_OPT trampoline
x86, hwmon: Fix unsafe smp_processor_id() in thermal_throttle_add_dev
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf, x86: Try to handle unknown nmis with an enabled PMU
perf, x86: Fix handle_irq return values
perf, x86: Fix accidentally ack'ing a second event on intel perf counter
oprofile, x86: fix init_sysfs() function stub
lockup_detector: Sync touch_*_watchdog back to old semantics
tracing: Fix a race in function profile
oprofile, x86: fix init_sysfs error handling
perf_events: Fix time tracking for events with pid != -1 and cpu != -1
perf: Initialize callchains roots's childen hits
oprofile: fix crash when accessing freed task structs
Top of kvm_kpic_state structure should have the same memory layout as
kvm_pic_state since it is copied by memcpy.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
operand::val and operand::orig_val are 32-bit on i386, whereas cmpxchg8b
operands are 64-bit.
Fix by adding val64 and orig_val64 union members to struct operand, and
using them where needed.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
PCI: bus speed strings should be const
PCI hotplug: Fix build with CONFIG_ACPI unset
PCI: PCIe: Remove the port driver module exit routine
PCI: PCIe: Move PCIe PME code to the pcie directory
PCI: PCIe: Disable PCIe port services during port initialization
PCI: PCIe: Ask BIOS for control of all native services at once
ACPI/PCI: Negotiate _OSC control bits before requesting them
ACPI/PCI: Do not preserve _OSC control bits returned by a query
ACPI/PCI: Make acpi_pci_query_osc() return control bits
ACPI/PCI: Reorder checks in acpi_pci_osc_control_set()
PCI: PCIe: Introduce commad line switch for disabling port services
PCI: PCIe AER: Introduce pci_aer_available()
x86/PCI: only define pci_domain_nr if PCI and PCI_DOMAINS are set
PCI: provide stub pci_domain_nr function for !CONFIG_PCI configs
This patch fixes the sparse warnings when the return pointer of
iomap_atomic_prot_pfn() is used as an argument of iowrite32()
and friends.
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
LKML-Reference: <1283633804-11749-1-git-send-email-currojerez@riseup.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When the PMU is enabled it is valid to have unhandled nmis, two
events could trigger 'simultaneously' raising two back-to-back
NMIs. If the first NMI handles both, the latter will be empty
and daze the CPU.
The solution to avoid an 'unknown nmi' massage in this case was
simply to stop the nmi handler chain when the PMU is enabled by
stating the nmi was handled. This has the drawback that a) we
can not detect unknown nmis anymore, and b) subsequent nmi
handlers are not called.
This patch addresses this. Now, we check this unknown NMI if it
could be a PMU back-to-back NMI. Otherwise we pass it and let
the kernel handle the unknown nmi.
This is a debug log:
cpu #6, nmi #32333, skip_nmi #32330, handled = 1, time = 1934364430
cpu #6, nmi #32334, skip_nmi #32330, handled = 1, time = 1934704616
cpu #6, nmi #32335, skip_nmi #32336, handled = 2, time = 1936032320
cpu #6, nmi #32336, skip_nmi #32336, handled = 0, time = 1936034139
cpu #6, nmi #32337, skip_nmi #32336, handled = 1, time = 1936120100
cpu #6, nmi #32338, skip_nmi #32336, handled = 1, time = 1936404607
cpu #6, nmi #32339, skip_nmi #32336, handled = 1, time = 1937983416
cpu #6, nmi #32340, skip_nmi #32341, handled = 2, time = 1938201032
cpu #6, nmi #32341, skip_nmi #32341, handled = 0, time = 1938202830
cpu #6, nmi #32342, skip_nmi #32341, handled = 1, time = 1938443743
cpu #6, nmi #32343, skip_nmi #32341, handled = 1, time = 1939956552
cpu #6, nmi #32344, skip_nmi #32341, handled = 1, time = 1940073224
cpu #6, nmi #32345, skip_nmi #32341, handled = 1, time = 1940485677
cpu #6, nmi #32346, skip_nmi #32347, handled = 2, time = 1941947772
cpu #6, nmi #32347, skip_nmi #32347, handled = 1, time = 1941949818
cpu #6, nmi #32348, skip_nmi #32347, handled = 0, time = 1941951591
Uhhuh. NMI received for unknown reason 00 on CPU 6.
Do you have a strange power saving mode enabled?
Dazed and confused, but trying to continue
Deltas:
nmi #32334 340186
nmi #32335 1327704
nmi #32336 1819 <<<< back-to-back nmi [1]
nmi #32337 85961
nmi #32338 284507
nmi #32339 1578809
nmi #32340 217616
nmi #32341 1798 <<<< back-to-back nmi [2]
nmi #32342 240913
nmi #32343 1512809
nmi #32344 116672
nmi #32345 412453
nmi #32346 1462095 <<<< 1st nmi (standard) handling 2 counters
nmi #32347 2046 <<<< 2nd nmi (back-to-back) handling one
counter nmi #32348 1773 <<<< 3rd nmi (back-to-back)
handling no counter! [3]
For back-to-back nmi detection there are the following rules:
The PMU nmi handler was handling more than one counter and no
counter was handled in the subsequent nmi (see [1] and [2]
above).
There is another case if there are two subsequent back-to-back
nmis [3]. The 2nd is detected as back-to-back because the first
handled more than one counter. If the second handles one counter
and the 3rd handles nothing, we drop the 3rd nmi because it
could be a back-to-back nmi.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
[ renamed nmi variable to pmu_nmi to avoid clash with .nmi in entry.S ]
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: peterz@infradead.org
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: <1283454469-1909-3-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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: Don 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: Ingo Molnar <mingo@elte.hu>
The use of the return value of init_sysfs() with commit
10f0412 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: Ingo Molnar <mingo@elte.hu>
Cc: stable@kernel.org
Signed-off-by: Robert Richter <robert.richter@amd.com>
Implements verification of
- Bits of ESCR EventMask field (meaningful bits in field are hardware
predefined and others bits should be set to zero)
- INSTR_COMPLETED event (it is available on predefined cpu model only)
- Thread shared events (they should be guarded by "perf_event_paranoid"
sysctl due to security reason). The side effect of this action is
that PERF_COUNT_HW_BUS_CYCLES become a "paranoid" general event.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Lin Ming <ming.m.lin@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20100825182334.GB14874@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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: Robert Richter <robert.richter@amd.com>
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf, x86, Pentium4: Clear the P4_CCCR_FORCE_OVF flag
tracing/trace_stack: Fix stack trace on ppc64
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep states
sched: Fix rq->clock synchronization when migrating tasks
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: Vince Weaver <vweaver1@eecs.utk.edu>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This fixes the following build warning introduced by the
callchain rework:
arch/x86/kernel/cpu/perf_event.c:1574: warning: ‘perf_callchain_entry_nmi’ defined but not used
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1282718949.16443.75.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
rc2 kernel crashes when booting second cpu on this CONFIG_VMSPLIT_2G_OPT
laptop: whereas cloning from kernel to low mappings pgd range does need
to limit by both KERNEL_PGD_PTRS and KERNEL_PGD_BOUNDARY, cloning kernel
pgd range itself must not be limited by the smaller KERNEL_PGD_BOUNDARY.
Signed-off-by: Hugh Dickins <hughd@google.com>
LKML-Reference: <alpine.LSU.2.00.1008242235120.2515@sister.anvils>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* 'for-upstream/pvhvm' of git://xenbits.xensource.com/people/ianc/linux-2.6:
xen: pvhvm: make it clearer that XEN_UNPLUG_* define bits in a bitfield
xen: pvhvm: rename xen_emul_unplug=ignore to =unnnecessary
xen: pvhvm: allow user to request no emulated device unplug
It is not immediately clear what this option causes to become
ignored. The actual meaning is that it is not necessary to unplug the
emulated devices to safely use the PV ones, even if the platform does
not support the unplug protocol. (pressumably the user will only add
this option if they have ensured that their domain configuration is
safe).
I think xen_emul_unplug=unnecessary better captures this.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>
this allows the user to disable pvhvm and revert to emulated devices
in case of a system misconfiguration (e.g. initramfs with only
emulated drivers in it).
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>
* 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: PIT: free irq source id in handling error path
KVM: destroy workqueue on kvm_create_pit() failures
KVM: fix poison overwritten caused by using wrong xstate size
The "Configure" word tends to make user believe they have to say 'yes'
to be able to choose the number of procs/nodes. "Enable" should be
unambiguous enough.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix BUG: using smp_processor_id() in preemptible thermal_throttle_add_dev.
We know the cpu number when calling thermal_throttle_add_dev, so we can
remove smp_processor_id call in thermal_throttle_add_dev by supplying
the cpu number as argument.
This should resolve kernel bugzilla 16615/16629.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
LKML-Reference: <20100820073634.GB5209@swordfish.minsk.epam.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Joerg Roedel <Joerg.Roedel@amd.com>
Cc: Maciej Rutecki <maciej.rutecki@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Fixes these build warnings introduced by the callchain
rework:
arch/x86/kernel/cpu/perf_event.c: In function ‘perf_callchain_kernel’:
arch/x86/kernel/cpu/perf_event.c:1646: warning: ‘return’ with a value, in function returning void
arch/x86/kernel/cpu/perf_event.c: In function ‘perf_callchain_user’:
arch/x86/kernel/cpu/perf_event.c:1699: warning: ‘return’ with a value, in function returning void
arch/x86/kernel/cpu/perf_event.c: At top level:
arch/x86/kernel/cpu/perf_event.c:1607: warning: ‘perf_callchain_entry_nmi’ defined but not used
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
TSC's get reset after suspend/resume (even on cpu's with invariant TSC
which runs at a constant rate across ACPI P-, C- and T-states). And in
some systems BIOS seem to reinit TSC to arbitrary large value (still
sync'd across cpu's) during resume.
This leads to a scenario of scheduler rq->clock (sched_clock_cpu()) less
than rq->age_stamp (introduced in 2.6.32). This leads to a big value
returned by scale_rt_power() and the resulting big group power set by the
update_group_power() is causing improper load balancing between busy and
idle cpu's after suspend/resume.
This resulted in multi-threaded workloads (like kernel-compilation) go
slower after suspend/resume cycle on core i5 laptops.
Fix this by recomputing cyc2ns_offset's during resume, so that
sched_clock() continues from the point where it was left off during
suspend.
Reported-by: Florian Pritz <flo@xssn.at>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <stable@kernel.org> # [v2.6.32+]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1282262618.2675.24.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix a boot crash when apic=debug is used and the APIC is
not properly initialized.
This issue appears during Xen Dom0 kernel boot but the
fix is generic and the crash could occur on real hardware
as well.
Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Cc: xen-devel@lists.xensource.com
Cc: konrad.wilk@oracle.com
Cc: jeremy@goop.org
Cc: <stable@kernel.org> # .35.x, .34.x, .33.x, .32.x
LKML-Reference: <20100819224616.GB9967@router-fw-old.local.net-space.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When testing cpu hotplug code on 32-bit we kept hitting the "CPU%d:
Stuck ??" message due to multiple cores concurrently accessing the
cpu_callin_mask, among others.
Since these codepaths are not protected from concurrent access due to
the fact that there's no sane reason for making an already complex
code unnecessarily more complex - we hit the issue only when insanely
switching cores off- and online - serialize hotplugging cores on the
sysfs level and be done with it.
[ v2.1: fix !HOTPLUG_CPU build ]
Cc: <stable@kernel.org>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20100819181029.GC17171@aftab>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
