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  1. 20 6月, 2013 1 次提交
  3. 13 6月, 2013 2 次提交
  5. 11 6月, 2013 8 次提交
  7. 10 6月, 2013 10 次提交
  9. 08 6月, 2013 2 次提交
    • D
      ARM: exynos: add debug_ll_io_init() call in exynos_init_io() · 9c1fcdcc
      由 Doug Anderson 提交于 
      If the early MMU mapping of the UART happens to get booted out of the
TLB between the start of paging_init() and when we finally re-add the
UART at the very end of s3c_init_cpu(), we'll get a hang at bootup if
we've got early_printk enabled.  Avoid this hang by calling
debug_ll_io_init() early.

Without this patch, you can reliably reproduce a hang when early
printk is enabled by adding flush_tlb_all() at the start of
exynos_init_io().  After this patch the hang goes away.
Signed-off-by: NDoug Anderson <dianders@chromium.org>
Acked-by: NKukjin Kim <kgene.kim@samsung.com>
Signed-off-by: NOlof Johansson <olof@lixom.net>
      9c1fcdcc
    • T
      ARM: EXYNOS: uncompress - print debug messages if DEBUG_LL is defined · 437d8ac5
      由 Tushar Behera 提交于 
      Printing low-level debug messages make an assumption that the specified
UART port has been preconfigured by the bootloader. Incorrectly
specified UART port results in system getting stalled while printing the
message "Uncompressing Linux... done, booting the kernel"
This UART port number is specified through S3C_LOWLEVEL_UART_PORT. Since
the UART port might different for different board, it is not possible to
specify it correctly for every board that use a common defconfig file.

Calling this print subroutine only when DEBUG_LL fixes the problem. By
disabling DEBUG_LL in default config file, we would be able to boot
multiple boards with different default UART ports.

With this current approach, we miss the print "Uncompressing Linux...
done, booting the kernel." when DEBUG_LL is not defined.
Signed-off-by: NTushar Behera <tushar.behera@linaro.org>
Signed-off-by: NOlof Johansson <olof@lixom.net>
      437d8ac5
  11. 06 6月, 2013 11 次提交
    • J
      MIPS: ralink: add missing SZ_1M multiplier · cdfce539
      由 John Crispin 提交于 
      On RT5350 the memory size is set to Bytes and not MegaBytes due to a missing
multiplier.
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Cc: John Crispin <blogic@openwrt.org>
Patchwork: https://patchwork.linux-mips.org/patch/5378/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
      cdfce539
    • R
      MIPS: Compat: Fix cputime_to_timeval() arguments in compat binfmt_elf. · 7b741aa4
      由 Ralf Baechle 提交于 
      cputime_to_timeval() takes a struct timeval *as its second argument but
a struct compat_timeval * will be passed resulting in:

  CC      arch/mips/kernel/binfmt_elfn32.o
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c: In function ‘fill_prstatus’:
arch/mips/kernel/../../../fs/binfmt_elf.c:1330:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1331:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1336:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1337:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1339:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfn32.c:122:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1340:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfn32.c:55:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
  AS      arch/mips/kernel/scall64-n32.o
  CC      arch/mips/kernel/signal_n32.o
  CC      arch/mips/kernel/binfmt_elfo32.o
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c: In function ‘fill_prstatus’:
arch/mips/kernel/../../../fs/binfmt_elf.c:1330:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1331:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1336:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1337:3: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1339:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
In file included from arch/mips/kernel/binfmt_elfo32.c:165:0:
arch/mips/kernel/../../../fs/binfmt_elf.c:1340:2: warning: passing argument 2 of ‘cputime_to_timeval’ from incompatible pointer type [enabled by default]
In file included from include/asm-generic/cputime.h:12:0,
                 from /home/ralf/src/linux/linux-mips/arch/mips/include/asm/cputime.h:4,
                 from include/linux/sched.h:28,
                 from include/linux/ptrace.h:5,
                 from include/uapi/linux/elfcore.h:7,
                 from include/linux/elfcore.h:7,
                 from arch/mips/kernel/binfmt_elfo32.c:78:
include/asm-generic/cputime_nsecs.h:92:91: note: expected ‘struct timeval *’ but argument is of type ‘struct compat_timeval *’
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
      7b741aa4
    • D
      MIPS: OCTEON: Improve _machine_halt implementation. · 38c3c0f6
      由 David Daney 提交于 
      As noted by Wladislav Wiebe:
   $ halt
   ..
   Sent SIGKILL to all processes
   Requesting system halt
   [66.729373] System halted.
   [66.733244]
   [66.734761] =====================================
   [66.739473] [ BUG: lock held at task exit time! ]
   [66.744188] 3.8.7-0-sampleversion-fct #49 Tainted: G           O
   [66.750202] -------------------------------------
   [66.754913] init/21479 is exiting with locks still held!
   [66.760234] 1 lock held by init/21479:
   [66.763990]  #0:  (reboot_mutex){+.+...}, at: [<ffffffff801776c8>] SyS_reboot+0xe0/0x218
   [66.772165]
   [66.772165] stack backtrace:
   [66.776532] Call Trace:
   [66.778992] [<ffffffff805780a8>] dump_stack+0x8/0x34
   [66.783972] [<ffffffff801618b0>] do_exit+0x610/0xa70
   [66.788948] [<ffffffff801777a8>] SyS_reboot+0x1c0/0x218
   [66.794186] [<ffffffff8013d6a4>] handle_sys64+0x44/0x64

This is an alternative fix to the one sent by Wladislav.  We kill the
watchdog for each CPU and then spin in WAIT with interrupts disabled.
This is the lowest power mode for the OCTEON.  If we were to spin with
interrupts enabled, we would get a continual stream of warning messages
and backtraces from the lockup detector, so I chose to disable
interrupts.
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Cc: Maxim Uvarov <muvarov@gmail.com>
Cc: Wladislav Wiebe <wladislav.kw@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/5324/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
      38c3c0f6
    • Y
      MIPS: rtlx: Fix implicit declaration of function set_vi_handler() · 406b5ee2
      由 Yoichi Yuasa 提交于 
      arch/mips/kernel/rtlx.c: In function 'rtlx_module_init':
arch/mips/kernel/rtlx.c:523:3: error: implicit declaration of function 'set_vi_handler' [-Werror=implicit-function-declaration]
Signed-off-by: NYoichi Yuasa <yuasa@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5340/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
      406b5ee2
    • P
      arch, mm: Remove tlb_fast_mode() · 29eb7782
      由 Peter Zijlstra 提交于 
      Since the introduction of preemptible mmu_gather TLB fast mode has been
broken. TLB fast mode relies on there being absolutely no concurrency;
it frees pages first and invalidates TLBs later.

However now we can get concurrency and stuff goes *bang*.

This patch removes all tlb_fast_mode() code; it was found the better
option vs trying to patch the hole by entangling tlb invalidation with
the scheduler.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Reported-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      29eb7782
    • W
      ARM: 7747/1: pcpu: ensure __my_cpu_offset cannot be re-ordered across barrier() · 509eb76e
      由 Will Deacon 提交于 
      __my_cpu_offset is non-volatile, since we want its value to be cached
when we access several per-cpu variables in a row with preemption
disabled. This means that we rely on preempt_{en,dis}able to hazard
with the operation via the barrier() macro, so that we can't end up
migrating CPUs without reloading the per-cpu offset.

Unfortunately, GCC doesn't treat a "memory" clobber on a non-volatile
asm block as a side-effect, and will happily re-order it before other
memory clobbers (including those in prempt_disable()) and cache the
value. This has been observed to break the cmpxchg logic in the slub
allocator, leading to livelock in kmem_cache_alloc in mainline kernels.

This patch adds a dummy memory input operand to __my_cpu_offset,
forcing it to be ordered with respect to the barrier() macro.

Cc: <stable@vger.kernel.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      509eb76e
    • M
      ARM: 7750/1: update legacy CPU ID in decompressor cache support jump table · ced2a3b8
      由 Marc C 提交于 
      The previous mask values for the legacy ARM CPU IDs were conflicting
with the CPU ID assignments for late-generation CPUs (like the
Qualcomm MSM/QSD or Broadcom Brahma-15 processors). This change
corrects the legacy ARM CPU ID value so that the jump table can
fall-through to the appropriate cache maintenance / MMU functions.
Signed-off-by: NMarc C <marc.ceeeee@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      ced2a3b8
    • A
      ARM: 7743/1: compressed/head.S: work around new binutils warning · da94a829
      由 Arnd Bergmann 提交于 
      In August 2012, Matthew Gretton-Dann checked a change into binutils
labelled "Error on obsolete & warn on deprecated registers", apparently as
part of ARMv8 support. Apparently, this was supposed to emit the message
"Warning: This coprocessor register access is deprecated in ARMv8" when
using certain mcr/mrc instructions and building for ARMv8. Unfortunately,
the message that is actually emitted appears to be '(null)', which is
less helpful in comparison.

Even more unfortunately, this is biting us on every single kernel
build with a new gas, because arch/arm/boot/compressed/head.S and some
other files in that directory are built with -march=all since kernel
commit 80cec14a "[ARM] Add -march=all to assembly file build in
arch/arm/boot/compressed" back in v2.6.28.

This patch reverts Russell's nice solution and instead marks the head.S
file to be built for armv7-a, which fortunately lets us build all
instructions in that file without warnings even on the broken binutils.

Without this patch, building anything results in:

arch/arm/boot/compressed/head.S: Assembler messages:
arch/arm/boot/compressed/head.S:565: Warning: (null)
arch/arm/boot/compressed/head.S:676: Warning: (null)
arch/arm/boot/compressed/head.S:698: Warning: (null)
arch/arm/boot/compressed/head.S:722: Warning: (null)
arch/arm/boot/compressed/head.S:726: Warning: (null)
arch/arm/boot/compressed/head.S:957: Warning: (null)
arch/arm/boot/compressed/head.S:996: Warning: (null)
arch/arm/boot/compressed/head.S:997: Warning: (null)
arch/arm/boot/compressed/head.S:1027: Warning: (null)
arch/arm/boot/compressed/head.S:1035: Warning: (null)
arch/arm/boot/compressed/head.S:1046: Warning: (null)
arch/arm/boot/compressed/head.S:1060: Warning: (null)
arch/arm/boot/compressed/head.S:1092: Warning: (null)
arch/arm/boot/compressed/head.S:1094: Warning: (null)
arch/arm/boot/compressed/head.S:1095: Warning: (null)
arch/arm/boot/compressed/head.S:1102: Warning: (null)
arch/arm/boot/compressed/head.S:1134: Warning: (null)
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org
Cc: Matthew Gretton-Dann <matthew.gretton-dann@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      da94a829
    • A
      ARM: 7742/1: topology: export cpu_topology · 92bdd3f5
      由 Arnd Bergmann 提交于 
      The cpu_topology symbol is required by any driver using the topology
interfaces, which leads to a couple of build errors:

ERROR: "cpu_topology" [drivers/net/ethernet/sfc/sfc.ko] undefined!
ERROR: "cpu_topology" [drivers/cpufreq/arm_big_little.ko] undefined!
ERROR: "cpu_topology" [drivers/block/mtip32xx/mtip32xx.ko] undefined!

The obvious solution is to export this symbol.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      92bdd3f5
    • N
      ARM: 7737/1: fix kernel decompressor compilation error with CONFIG_DEBUG_SEMIHOSTING · 27523679
      由 Nicolas Pitre 提交于 
      Selecting this option produces:

  AS      arch/arm/boot/compressed/debug.o
arch/arm/boot/compressed/debug.S:4:33: fatal error: mach/debug-macro.S: No such file or directory
compilation terminated.
make[3]: *** [arch/arm/boot/compressed/debug.o] Error 1

The semihosting support cannot be modelled into a senduart macro as
it requires memory space for argument passing.  So the
CONFIG_DEBUG_LL_INCLUDE may not have any sensible value and the include
directive should be omitted.

While at it, let's add proper semihosting output support to the
decompressor.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      27523679
    • M
      x86/PCI: Map PCI setup data with ioremap() so it can be in highmem · 65694c5a
      由 Matt Fleming 提交于 
      f9a37be0 ("x86: Use PCI setup data") added support for using PCI ROM
images from setup_data.  This used phys_to_virt(), which is not valid for
highmem addresses, and can cause a crash when booting a 32-bit kernel via
the EFI boot stub.

pcibios_add_device() assumes that the physical addresses stored in
setup_data are accessible via the direct kernel mapping, and that calling
phys_to_virt() is valid.  This isn't guaranteed to be true on x86 where the
direct mapping range is much smaller than on x86-64.

Calling phys_to_virt() on a highmem address results in the following:

 BUG: unable to handle kernel paging request at 39a3c198
 IP: [<c262be0f>] pcibios_add_device+0x2f/0x90
 ...
 Call Trace:
  [<c2370c73>] pci_device_add+0xe3/0x130
  [<c274640b>] pci_scan_single_device+0x8b/0xb0
  [<c2370d08>] pci_scan_slot+0x48/0x100
  [<c2371904>] pci_scan_child_bus+0x24/0xc0
  [<c262a7b0>] pci_acpi_scan_root+0x2c0/0x490
  [<c23b7203>] acpi_pci_root_add+0x312/0x42f
  ...

The solution is to use ioremap() instead of phys_to_virt() to map the
setup data into the kernel address space.

[bhelgaas: changelog]
Tested-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: stable@vger.kernel.org	# v3.8+
      65694c5a
  13. 05 6月, 2013 5 次提交
  15. 04 6月, 2013 1 次提交
    • K
      xen/smp: Fixup NOHZ per cpu data when onlining an offline CPU. · 466318a8
      由 Konrad Rzeszutek Wilk 提交于 
      The xen_play_dead is an undead function. When the vCPU is told to
offline it ends up calling xen_play_dead wherin it calls the
VCPUOP_down hypercall which offlines the vCPU. However, when the
vCPU is onlined back, it resumes execution right after
VCPUOP_down hypercall.

That was OK (albeit the API for play_dead assumes that the CPU
stays dead and never returns) but with commit 4b0c0f29
(tick: Cleanup NOHZ per cpu data on cpu down) that is no longer safe
as said commit resets the ts->inidle which at the start of the
cpu_idle loop was set.

The net effect is that we get this warn:

Broke affinity for irq 16
installing Xen timer for CPU 1
cpu 1 spinlock event irq 48
------------[ cut here ]------------
WARNING: at /home/konrad/linux-linus/kernel/time/tick-sched.c:935 tick_nohz_idle_exit+0x195/0x1b0()
Modules linked in: dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.10.0-rc3upstream-00068-gdcdbe33a #1
Hardware name: BIOSTAR Group N61PB-M2S/N61PB-M2S, BIOS 6.00 PG 09/03/2009
 ffffffff8193b448 ffff880039da5e60 ffffffff816707c8 ffff880039da5ea0
 ffffffff8108ce8b ffff880039da4010 ffff88003fa8e500 ffff880039da4010
 0000000000000001 ffff880039da4000 ffff880039da4010 ffff880039da5eb0
Call Trace:
 [<ffffffff816707c8>] dump_stack+0x19/0x1b
 [<ffffffff8108ce8b>] warn_slowpath_common+0x6b/0xa0
 [<ffffffff8108ced5>] warn_slowpath_null+0x15/0x20
 [<ffffffff810e4745>] tick_nohz_idle_exit+0x195/0x1b0
 [<ffffffff810da755>] cpu_startup_entry+0x205/0x250
 [<ffffffff81661070>] cpu_bringup_and_idle+0x13/0x15
---[ end trace 915c8c486004dda1 ]---

b/c ts_inidle is set to zero. Thomas suggested that we just add a workaround
to call tick_nohz_idle_enter before returning from xen_play_dead() - and
that is what this patch does and fixes the issue.

We also add the stable part b/c git commit 4b0c0f29 is on the stable
tree.

CC: stable@vger.kernel.org
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      466318a8