Currently, we can hit a nasty case with optimistic
spinning on mutexes:

    CPU A tries to take a mutex, while holding the BKL

    CPU B tried to take the BLK while holding the mutex

This looks like a AB-BA scenario but in practice, is
allowed and happens due to the auto-release on
schedule() nature of the BKL.

In that case, the optimistic spinning code can get us
into a situation where instead of going to sleep, A
will spin waiting for B who is spinning waiting for
A, and the only way out of that loop is the
need_resched() test in mutex_spin_on_owner().

This patch fixes it by completely disabling spinning
if we own the BKL. This adds one more detail to the
extensive list of reasons why it's a bad idea for
kernel code to be holding the BKL.
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: <stable@kernel.org>
LKML-Reference: <20100519054636.GC12389@ozlabs.org>
[ added an unlikely() attribute to the branch ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* 'x86-uv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, UV: uv_irq.c: Fix all sparse warnings
  x86, UV: Improve BAU performance and error recovery
  x86, UV: Delete unneeded boot messages
  x86, UV: Clean up UV headers for MMR definitions

* 'x86-txt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, tboot: Add support for S3 memory integrity protection

* 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, pat: Update the page flags for memtype atomically instead of using memtype_lock
  x86, pat: In rbt_memtype_check_insert(), update new->type only if valid
  x86, pat: Migrate to rbtree only backend for pat memtype management
  x86, pat: Preparatory changes in pat.c for bigger rbtree change
  rbtree: Add support for augmented rbtrees

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

* 'x86-mrst-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, mrst: add nop functions to x86_init mpparse functions
  x86, mrst, pci: return 0 for non-present pci bars
  x86: Avoid check hlt for newer cpus

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86-64: Combine SRAT regions when possible

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

* 'x86-microcode-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86/microcode: Use nonseekable_open()
  x86: Improve Intel microcode loader performance

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

* 'core-hweight-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, hweight: Use a 32-bit popcnt for __arch_hweight32()
  arch, hweight: Fix compilation errors
  x86: Add optimized popcnt variants
  bitops: Optimize hweight() by making use of compile-time evaluation

* 'x86-irq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, acpi/irq: Define gsi_end when X86_IO_APIC is undefined
  x86, irq: Kill io_apic_renumber_irq
  x86, acpi/irq: Handle isa irqs that are not identity mapped to gsi's.
  x86, ioapic: Simplify probe_nr_irqs_gsi.
  x86, ioapic: Optimize pin_2_irq
  x86, ioapic: Move nr_ioapic_registers calculation to mp_register_ioapic.
  x86, ioapic: In mpparse use mp_register_ioapic
  x86, ioapic: Teach mp_register_ioapic to compute a global gsi_end
  x86, ioapic: Fix the types of gsi values
  x86, ioapic: Fix io_apic_redir_entries to return the number of entries.
  x86, ioapic: Only export mp_find_ioapic and mp_find_ioapic_pin in io_apic.h
  x86, acpi/irq: Generalize mp_config_acpi_legacy_irqs
  x86, acpi/irq: Fix acpi_sci_ioapic_setup so it has both bus_irq and gsi
  x86, acpi/irq: pci device dev->irq is an isa irq not a gsi
  x86, acpi/irq: Teach acpi_get_override_irq to take a gsi not an isa_irq
  x86, acpi/irq: Introduce apci_isa_irq_to_gsi

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, fpu: Use static_cpu_has() to implement use_xsave()
  x86: Add new static_cpu_has() function using alternatives
  x86, fpu: Use the proper asm constraint in use_xsave()
  x86, fpu: Unbreak FPU emulation
  x86: Introduce 'struct fpu' and related API
  x86: Eliminate TS_XSAVE
  x86-32: Don't set ignore_fpu_irq in simd exception
  x86: Merge kernel_math_error() into math_error()
  x86: Merge simd_math_error() into math_error()
  x86-32: Rework cache flush denied handler

Fix trivial conflict in arch/x86/kernel/process.c

* 'x86-doc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, docbook: Fix errors from x86 headers merger

* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, hypervisor: add missing <linux/module.h>
  Modify the VMware balloon driver for the new x86_hyper API
  x86, hypervisor: Export the x86_hyper* symbols
  x86: Clean up the hypervisor layer
  x86, HyperV: fix up the license to mshyperv.c
  x86: Detect running on a Microsoft HyperV system
  x86, cpu: Make APERF/MPERF a normal table-driven flag
  x86, k8: Fix build error when K8_NB is disabled
  x86, cacheinfo: Disable index in all four subcaches
  x86, cacheinfo: Make L3 cache info per node
  x86, cacheinfo: Reorganize AMD L3 cache structure
  x86, cacheinfo: Turn off L3 cache index disable feature in virtualized environments
  x86, cacheinfo: Unify AMD L3 cache index disable checking
  cpufreq: Unify sysfs attribute definition macros
  powernow-k8: Fix frequency reporting
  x86, cpufreq: Add APERF/MPERF support for AMD processors
  x86: Unify APERF/MPERF support
  powernow-k8: Add core performance boost support
  x86, cpu: Add AMD core boosting feature flag to /proc/cpuinfo

Fix up trivial conflicts in arch/x86/kernel/cpu/intel_cacheinfo.c and
drivers/cpufreq/cpufreq_ondemand.c

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

* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Clean up arch/x86/Kconfig*
  x86-64: Don't export init_level4_pgt

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

* 'x86-atomic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Fix LOCK_PREFIX_HERE for uniprocessor build
  x86, atomic64: In selftest, distinguish x86-64 from 586+
  x86-32: Fix atomic64_inc_not_zero return value convention
  lib: Fix atomic64_inc_not_zero test
  lib: Fix atomic64_add_unless return value convention
  x86-32: Fix atomic64_add_unless return value convention
  lib: Fix atomic64_add_unless test
  x86: Implement atomic[64]_dec_if_positive()
  lib: Only test atomic64_dec_if_positive on archs having it
  x86-32: Rewrite 32-bit atomic64 functions in assembly
  lib: Add self-test for atomic64_t
  x86-32: Allow UP/SMP lock replacement in cmpxchg64
  x86: Add support for lock prefix in alternatives

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Use .cfi_sections for assembly code
  x86-64: Reduce SMP locks table size
  x86, asm: Introduce and use percpu_inc()

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

* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing: Fix "integer as NULL pointer" warning.
  tracing: Fix tracepoint.h DECLARE_TRACE() to allow more than one header
  tracing: Make the documentation clear on trace_event boot option
  ring-buffer: Wrap open-coded WARN_ONCE
  tracing: Convert nop macros to static inlines
  tracing: Fix sleep time function profiling
  tracing: Show sample std dev in function profiling
  tracing: Add documentation for trace commands mod, traceon/traceoff
  ring-buffer: Make benchmark handle missed events
  ring-buffer: Make non-consuming read less expensive with lots of cpus.
  tracing: Add graph output support for irqsoff tracer
  tracing: Have graph flags passed in to ouput functions
  tracing: Add ftrace events for graph tracer
  tracing: Dump either the oops's cpu source or all cpus buffers
  tracing: Fix uninitialized variable of tracing/trace output

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

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits)
  stop_machine: Move local variable closer to the usage site in cpu_stop_cpu_callback()
  sched, wait: Use wrapper functions
  sched: Remove a stale comment
  ondemand: Make the iowait-is-busy time a sysfs tunable
  ondemand: Solve a big performance issue by counting IOWAIT time as busy
  sched: Intoduce get_cpu_iowait_time_us()
  sched: Eliminate the ts->idle_lastupdate field
  sched: Fold updating of the last_update_time_info into update_ts_time_stats()
  sched: Update the idle statistics in get_cpu_idle_time_us()
  sched: Introduce a function to update the idle statistics
  sched: Add a comment to get_cpu_idle_time_us()
  cpu_stop: add dummy implementation for UP
  sched: Remove rq argument to the tracepoints
  rcu: need barrier() in UP synchronize_sched_expedited()
  sched: correctly place paranioa memory barriers in synchronize_sched_expedited()
  sched: kill paranoia check in synchronize_sched_expedited()
  sched: replace migration_thread with cpu_stop
  stop_machine: reimplement using cpu_stop
  cpu_stop: implement stop_cpu[s]()
  sched: Fix select_idle_sibling() logic in select_task_rq_fair()
  ...

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

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (311 commits)
  perf tools: Add mode to build without newt support
  perf symbols: symbol inconsistency message should be done only at verbose=1
  perf tui: Add explicit -lslang option
  perf options: Type check all the remaining OPT_ variants
  perf options: Type check OPT_BOOLEAN and fix the offenders
  perf options: Check v type in OPT_U?INTEGER
  perf options: Introduce OPT_UINTEGER
  perf tui: Add workaround for slang < 2.1.4
  perf record: Fix bug mismatch with -c option definition
  perf options: Introduce OPT_U64
  perf tui: Add help window to show key associations
  perf tui: Make <- exit menus too
  perf newt: Add single key shortcuts for zoom into DSO and threads
  perf newt: Exit browser unconditionally when CTRL+C, q or Q is pressed
  perf newt: Fix the 'A'/'a' shortcut for annotate
  perf newt: Make <- exit the ui_browser
  x86, perf: P4 PMU - fix counters management logic
  perf newt: Make <- zoom out filters
  perf report: Report number of events, not samples
  perf hist: Clarify events_stats fields usage
  ...

Fix up trivial conflicts in kernel/fork.c and tools/perf/builtin-record.c

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

* 'oprofile-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
  oprofile/x86: make AMD IBS hotplug capable
  oprofile/x86: notify cpus only when daemon is running
  oprofile/x86: reordering some functions
  oprofile/x86: stop disabled counters in nmi handler
  oprofile/x86: protect cpu hotplug sections
  oprofile/x86: remove CONFIG_SMP macros
  oprofile/x86: fix uninitialized counter usage during cpu hotplug
  oprofile/x86: remove duplicate IBS capability check
  oprofile/x86: move IBS code
  oprofile/x86: return -EBUSY if counters are already reserved
  oprofile/x86: moving shutdown functions
  oprofile/x86: reserve counter msrs pairwise
  oprofile/x86: rework error handler in nmi_setup()
  oprofile: update file list in MAINTAINERS file
  oprofile: protect from not being in an IRQ context
  oprofile: remove double ring buffering
  ring-buffer: Add lost event count to end of sub buffer
  tracing: Show the lost events in the trace_pipe output
  ring-buffer: Add place holder recording of dropped events
  tracing: Fix compile error in module tracepoints when MODULE_UNLOAD not set
  ...

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

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
  rcu: remove all rcu head initializations, except on_stack initializations
  rcu head introduce rcu head init on stack
  Debugobjects transition check
  rcu: fix build bug in RCU_FAST_NO_HZ builds
  rcu: RCU_FAST_NO_HZ must check RCU dyntick state
  rcu: make SRCU usable in modules
  rcu: improve the RCU CPU-stall warning documentation
  rcu: reduce the number of spurious RCU_SOFTIRQ invocations
  rcu: permit discontiguous cpu_possible_mask CPU numbering
  rcu: improve RCU CPU stall-warning messages
  rcu: print boot-time console messages if RCU configs out of ordinary
  rcu: disable CPU stall warnings upon panic
  rcu: enable CPU_STALL_VERBOSE by default
  rcu: slim down rcutiny by removing rcu_scheduler_active and friends
  rcu: refactor RCU's context-switch handling
  rcu: rename rcutiny rcu_ctrlblk to rcu_sched_ctrlblk
  rcu: shrink rcutiny by making synchronize_rcu_bh() be inline
  rcu: fix now-bogus rcu_scheduler_active comments.
  rcu: Fix bogus CONFIG_PROVE_LOCKING in comments to reflect reality.
  rcu: ignore offline CPUs in last non-dyntick-idle CPU check
  ...

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

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  lockdep: Reduce stack_trace usage
  lockdep: No need to disable preemption in debug atomic ops
  lockdep: Actually _dec_ in debug_atomic_dec
  lockdep: Provide off case for redundant_hardirqs_on increment
  lockdep: Simplify debug atomic ops
  lockdep: Fix redundant_hardirqs_on incremented with irqs enabled
  lockstat: Make lockstat counting per cpu
  i8253: Convert i8253_lock to raw_spinlock

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

* 'core-iommu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86/amd-iommu: Add amd_iommu=off command line option
  iommu-api: Remove iommu_{un}map_range functions
  x86/amd-iommu: Implement ->{un}map callbacks for iommu-api
  x86/amd-iommu: Make amd_iommu_iova_to_phys aware of multiple page sizes
  x86/amd-iommu: Make iommu_unmap_page and fetch_pte aware of page sizes
  x86/amd-iommu: Make iommu_map_page and alloc_pte aware of page sizes
  kvm: Change kvm_iommu_map_pages to map large pages
  VT-d: Change {un}map_range functions to implement {un}map interface
  iommu-api: Add ->{un}map callbacks to iommu_ops
  iommu-api: Add iommu_map and iommu_unmap functions
  iommu-api: Rename ->{un}map function pointers to ->{un}map_range

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

* 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  debugobjects: Section mismatch cleanup

* git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6: (23 commits)
  cifs: fix noserverino handling when unix extensions are enabled
  cifs: don't update uniqueid in cifs_fattr_to_inode
  cifs: always revalidate hardlinked inodes when using noserverino
  [CIFS] drop quota operation stubs
  cifs: propagate cifs_new_fileinfo() error back to the caller
  cifs: add comments explaining cifs_new_fileinfo behavior
  cifs: remove unused parameter from cifs_posix_open_inode_helper()
  [CIFS] Remove unused cifs_oplock_cachep
  cifs: have decode_negTokenInit set flags in server struct
  cifs: break negotiate protocol calls out of cifs_setup_session
  cifs: eliminate "first_time" parm to CIFS_SessSetup
  [CIFS] Fix lease break for writes
  cifs: save the dialect chosen by server
  cifs: change && to ||
  cifs: rename "extended_security" to "global_secflags"
  cifs: move tcon find/create into separate function
  cifs: move SMB session creation code into separate function
  cifs: track local_nls in volume info
  [CIFS] Allow null nd (as nfs server uses) on create
  [CIFS] Fix losing locks during fork()
  ...

This addresses the following compiler warning:

 kernel/stop_machine.c: In function 'cpu_stop_cpu_callback':
 kernel/stop_machine.c:297: warning: unused variable 'work'

Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <tip-3fc1f1e2@git.kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Use a 32-bit popcnt instruction for __arch_hweight32(), even on
x86-64.  Even though the input register will *usually* be
zero-extended due to the standard operation of the hardware, it isn't
necessarily so if the input value was the result of truncating a
64-bit operation.

Note: the POPCNT32 variant used on x86-64 has a technically
unnecessary REX prefix to make it five bytes long, the same as a CALL
instruction, therefore avoiding an unnecessary NOP.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <alpine.LFD.2.00.1005171443060.4195@i5.linux-foundation.org>

make NO_NEWT=1

Will avoid building the newt (tui) support.
Suggested-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The uniqueid field sent by the server when unix extensions are enabled
is currently used sometimes when it shouldn't be. The readdir codepath
is correct, but most others are not. Fix it.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

That happened for an old perf.data file that had no fake MMAP events for
the kernel modules, but even then it should warn once for each module,
not one time for every symbol in every module not found.
Reported-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We use this value to find an inode within the hash bucket, so we can't
change this without re-hashing the inode. For now, treat this value
as immutable.

Eventually, we should probably use an inode number change on a path
based operation to indicate that the lookup cache is invalid, but that's
a bit more code to deal with.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

The old cifs_revalidate logic always revalidated hardlinked inodes.
This hack allowed CIFS to pass some connectathon tests when server inode
numbers aren't used (basic test7, in particular).
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k: amiga - Floppy platform device conversion
  m68k: amiga - Sound platform device conversion
  m68k: amiga - Frame buffer platform device conversion
  m68k: amiga - Zorro host bridge platform device conversion
  m68k: amiga - Zorro bus modalias support
  platform: Make platform resource input parameters const
  m68k: invoke oom-killer from page fault
  serial167: Kill unused variables
  m68k: Implement generic_find_next_{zero_,}le_bit()
  m68k: hp300 - Checkpatch cleanup
  m68k: Remove trailing spaces in messages
  m68k: Simplify param.h by using <asm-generic/param.h>
  m68k: Remove BKL from rtc implementations

* git://git.kernel.org/pub/scm/linux/kernel/git/joern/logfs:
  logfs: handle powerfail on NAND flash
  logfs: handle errors from get_mtd_device()
  logfs: remove unused variable
  logfs: fix sync
  logfs: fix compile failure
  logfs: initialize li->li_refcount
  logfs: commit reservations under space pressure
  logfs: survive logfs_buf_recover read errors
  logfs: Close i_ino reuse race
  logfs: fix logfs_seek_hole()
  logfs: Return -EINVAL if filesystem image doesn't match
  LogFS: Fix typo in b6349ac8
  logfs: testing the wrong variable

* 'bkl/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing:
  ptrace: Cleanup useless header
  ptrace: kill BKL in ptrace syscall

At least on rawhide using -lnewt is not enough if we use SLang routines
directly, so add an explicit -lslang since we use SLang routines.
Reported-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Add Amiga Zorro bus modalias and uevent support
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>