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Srivatsa S. Bhat 43ea953649 xen, balloon: Fix CPU hotplug callback registration 
Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

The xen balloon driver doesn't take get/put_online_cpus() around this code,
but that is also buggy, since it can miss CPU hotplug events in between the
initialization and callback registration:

	for_each_online_cpu(cpu)
		init_cpu(cpu);
		   ^
		   |  Race window; Can miss CPU hotplug events here.
		   v
	register_cpu_notifier(&foobar_cpu_notifier);

Interestingly, the balloon code in xen can simply be reorganized as shown
below, to have a race-free method to register hotplug callbacks, without even
taking get/put_online_cpus(). This is because the initialization performed for
already online CPUs is exactly the same as that performed for CPUs that come
online later. Moreover, the code has checks in place to avoid double
initialization.

	register_cpu_notifier(&foobar_cpu_notifier);

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	put_online_cpus();

A hotplug operation that occurs between registering the notifier and calling
get_online_cpus(), won't disrupt anything, because the code takes care to
perform the memory allocations only once.

So reorganize the balloon code in xen this way to fix the issues with CPU
hotplug callback registration.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 		2014-03-20 13:43:48 +01:00
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accessibility
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acpi ACPI / sleep: Add extra checks for HW Reduced ACPI mode sleep states 2014-03-13 22:11:39 +01:00
amba
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ata Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2014-03-10 12:56:24 -07:00
atm
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auxdisplay
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base drivers/base/topology.c: Fix CPU hotplug callback registration 2014-03-20 13:43:45 +01:00
bcma Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2014-01-30 17:20:32 -08:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2014-03-07 09:59:44 -08:00
bluetooth
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bus drivers: bus: fix CCI driver kcalloc call parameters swap 2014-01-31 15:15:13 -08:00
cdrom Merge branch 'for-3.14/drivers' of git://git.kernel.dk/linux-block 2014-01-30 11:40:10 -08:00
char Char/Misc fixes for 3.14-rc3 2014-02-14 16:13:00 -08:00
clk Single fix for a clock driver merged in 3.14-rc1. Without this fix the 2014-03-08 10:51:30 -08:00
clocksource clocksource, dummy-timer: Fix CPU hotplug callback registration 2014-03-20 13:43:45 +01:00
connector
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cpufreq acpi-cpufreq: Fix CPU hotplug callback registration 2014-03-20 13:43:45 +01:00
cpuidle powerpc/powernv/cpuidle: Back-end cpuidle driver for powernv platform. 2014-01-29 17:02:24 +11:00
crypto crypto/nx/nx-842: Fix handling of vmalloc addresses 2014-02-11 11:24:49 +11:00
dca
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devfreq Merge branches 'pm-cpufreq' and 'pm-devfreq' 2014-01-29 11:48:23 +01:00
dio
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dma Merge branch 'fixes' of git://git.infradead.org/users/vkoul/slave-dma 2014-03-01 21:30:43 -06:00
edac i7300_edac: Fix device reference count 2014-02-25 09:43:13 +01:00
eisa Revert "EISA: Initialize device before its resources" 2014-01-17 14:57:29 -07:00
extcon ASoC: dapm: Add locking to snd_soc_dapm_xxxx_pin functions 2014-02-20 18:40:07 +09:00
firewire Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2014-03-08 11:51:13 -08:00
firmware firmware/google: drop 'select EFI' to avoid recursive dependency 2014-01-27 21:02:40 -08:00
fmc drivers/fmc/fmc-write-eeprom.c: fix decimal permissions 2014-02-25 15:25:43 -08:00
gpio gpio: tb10x: GPIO_TB10X needs to select GENERIC_IRQ_CHIP 2014-02-05 11:13:59 +01:00
gpu Merge tag 'ttm-fixes-3.14-2014-03-12' of git://people.freedesktop.org/~thomash/linux into drm-fixes 2014-03-13 17:31:24 +10:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2014-02-18 16:29:46 -08:00
hsi
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hv Drivers: hv: vmbus: Don't timeout during the initial connection with host 2014-02-07 08:27:34 -08:00
hwmon hwmon, via-cputemp: Fix CPU hotplug callback registration 2014-03-20 13:43:48 +01:00
hwspinlock
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i2c i2c: Remove usage of orphaned symbol OF_I2C 2014-03-13 22:33:44 +01:00
ide drivers: ide: Include appropriate header file in ide-pio-blacklist.c 2014-01-28 23:35:09 -08:00
idle intel-idle: Fix CPU hotplug callback registration 2014-03-20 13:43:46 +01:00
iio iio:gyro: bug on L3GD20H gyroscope support 2014-02-18 10:24:49 +00:00
infiniband Merge git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2014-03-09 13:50:14 -07:00
input ASoC: dapm: Add locking to snd_soc_dapm_xxxx_pin functions 2014-02-20 18:40:07 +09:00
iommu drivers/iommu/omap-iommu-debug.c: fix decimal permissions 2014-02-25 15:25:42 -08:00
ipack
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irqchip irq-metag*: stop set_affinity vectoring to offline cpus 2014-02-25 22:35:06 +00:00
isdn isdn/hisax: hex vs decimal typo in prfeatureind() 2014-02-06 21:18:06 -08:00
leds Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds 2014-01-28 18:53:01 -08:00
lguest
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macintosh Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-27 21:11:26 -08:00
mailbox drivers/mailbox/omap: make mbox->irq signed for error handling 2014-01-23 16:36:53 -08:00
md dm cache: fix access beyond end of origin device 2014-03-12 13:52:00 -04:00
media [media] adv7842: Composite free-run platfrom-data fix 2014-02-04 06:46:10 -02:00
memory
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memstick drivers/memstick/host/rtsx_pci_ms.c: fix ms card data transfer bug 2014-01-23 16:37:04 -08:00
message drivers/message/i2o/i2o_config.c: fix deadlock in compat_ioctl(I2OGETIOPS) 2014-02-10 16:01:40 -08:00
mfd sound fixes for 3.14-rc4 2014-02-21 09:55:32 -08:00
misc mm: fix GFP_THISNODE callers and clarify 2014-03-10 17:26:19 -07:00
mmc Fix uses of dma_max_pfn() when converting to a limiting address 2014-02-17 23:08:41 +00:00
mtd Just a single fix for the UBI module unload path which makes sure we do not 2014-02-27 10:36:50 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-03-13 20:38:36 -07:00
nfc
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ntb
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nubus
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of Device tree compatible match order bug fix 2014-02-21 14:35:05 -08:00
oprofile oprofile, nmi-timer: Fix CPU hotplug callback registration 2014-03-20 13:43:46 +01:00
parisc
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parport TTY/Serial driver patches for 3.14-rc1 2014-01-20 16:05:23 -08:00
pci PCI: Don't check resource_size() in pci_bus_alloc_resource() 2014-03-12 11:19:20 -06:00
pcmcia PCI changes for the v3.14 merge window: 2014-01-22 16:39:28 -08:00
phy phy: let phy_provider_register be the last step in registering PHY 2014-02-18 12:13:16 -08:00
pinctrl ARM: SoC fixes for 3.14-rc 2014-03-09 19:27:31 -07:00
platform platform/chrome: Cleanups and improvements 2014-01-29 20:06:01 -08:00
pnp PNP / ACPI: proper handling of ACPI IO/Memory resource parsing failures 2014-03-11 21:22:10 +01:00
power Few fixes: 2014-02-14 10:32:28 -08:00
powercap powercap, intel-rapl: Fix CPU hotplug callback registration 2014-03-20 13:43:44 +01:00
pps
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ps3
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ptp
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pwm pwm: lp3943: Fix potential memory leak during request 2014-02-26 15:45:12 +01:00
rapidio rapidio/tsi721: fix tasklet termination in dma channel release 2014-03-04 07:55:49 -08:00
regulator regulator: Fixes for v3.14-rc5 2014-03-04 08:41:42 -08:00
remoteproc
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reset
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rpmsg
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rtc drivers/rtc/rtc-s3c.c: fix incorrect way of save/restore of S3C2410_TICNT for TYPE_S3C64XX 2014-03-04 07:55:48 -08:00
s390 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-03-04 08:44:32 -08:00
sbus Sparc: sparc_cpu_model isn't in asm/system.h any more [ver #2] 2014-02-20 13:34:11 -05:00
scsi scsi, fcoe: Fix CPU hotplug callback registration 2014-03-20 13:43:45 +01:00
sfi
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sh
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sn
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spi Merge remote-tracking branches 'spi/fix/ath79', 'spi/fix/atmel', 'spi/fix/coldfire', 'spi/fix/fsl-dspi', 'spi/fix/imx' and 'spi/fix/topcliff-pch' into spi-linus 2014-03-07 11:08:13 +08:00
ssb Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2014-01-30 17:20:32 -08:00
staging staging/cxt1e1/linux.c: Correct arbitrary memory write in c4_ioctl() 2014-03-04 16:20:01 -08:00
target Target/sbc: Fix sbc_copy_prot for offset scatters 2014-03-06 20:52:11 -08:00
tc
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thermal thermal, x86-pkg-temp: Fix CPU hotplug callback registration 2014-03-20 13:43:47 +01:00
tty Revert "tty: Set correct tty name in 'active' sysfs attribute" 2014-02-22 14:31:04 -08:00
uio
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usb Revert "xhci 1.0: Limit arbitrarily-aligned scatter gather." 2014-03-07 11:48:13 -08:00
uwb
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vfio mm: close PageTail race 2014-03-04 07:55:47 -08:00
vhost Merge git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2014-03-01 21:33:09 -06:00
video video: Kconfig: Allow more broad selection of the imxfb framebuffer driver. 2014-02-14 10:44:52 +02:00
virt
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virtio A few simple fixes. Quiet cycle. 2014-01-22 22:24:35 -08:00
vlynq drivers/vlynq/vlynq.c: fix another resource size off by 1 error 2014-01-23 16:36:55 -08:00
vme VME: Correct read/write alignment algorithm 2014-02-07 08:16:14 -08:00
w1 drivers/w1/masters/w1-gpio.c: add strong pullup emulation 2014-01-23 16:37:04 -08:00
watchdog octeon, watchdog: Fix CPU hotplug callback registration 2014-03-20 13:43:46 +01:00
xen xen, balloon: Fix CPU hotplug callback registration 2014-03-20 13:43:48 +01:00
zorro
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Kconfig
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Makefile
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