linux/drivers
Laszlo Ersek 08e34eb14f xen-netfront: delay gARP until backend switches to Connected
After a guest is live migrated, the xen-netfront driver emits a gratuitous
ARP message, so that networking hardware on the target host's subnet can
take notice, and public routing to the guest is re-established. However,
if the packet appears on the backend interface before the backend is added
to the target host's bridge, the packet is lost, and the migrated guest's
peers become unable to talk to the guest.

A sufficient two-parts condition to prevent the above is:

(1) ensure that the backend only moves to Connected xenbus state after its
hotplug scripts completed, ie. the netback interface got added to the
bridge; and

(2) ensure the frontend only queues the gARP when it sees the backend move
to Connected.

These two together provide complete ordering. Sub-condition (1) is already
satisfied by commit f942dc2552 in Linus' tree, based on commit
6b0b80ca7165 from [1].

In general, the full condition is sufficient, not necessary, because,
according to [2], live migration has been working for a long time without
satisfying sub-condition (2). However, after 6b0b80ca7165 was backported
to the RHEL-5 host to ensure (1), (2) still proved necessary in the RHEL-6
guest. This patch intends to provide (2) for upstream.

The Reviewed-by line comes from [3].

[1] git://xenbits.xen.org/people/ianc/linux-2.6.git#upstream/dom0/backend/netback-history
[2] http://old-list-archives.xen.org/xen-devel/2011-06/msg01969.html
[3] http://old-list-archives.xen.org/xen-devel/2011-07/msg00484.html

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-12-12 19:02:41 -05:00
..
accessibility
acpi pstore: pass allocated memory region back to caller 2011-11-17 12:58:07 -08:00
amba
ata libata: fix build without BMDMA 2011-11-17 02:11:42 -05:00
atm atm: eliminate atm_guess_pdu2truesize() 2011-11-26 16:40:30 -05:00
auxdisplay
base Merge branch 'driver-core-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core 2011-11-21 20:36:26 -08:00
bcma bcma: pci: use fixed windows when possible 2011-12-06 16:07:07 -05:00
block paride: fix potential information leak in pg_read() 2011-11-16 09:21:50 +01:00
bluetooth Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/padovan/bluetooth-next 2011-12-06 16:02:05 -05:00
cdrom
char fix typo/thinko in get_random_bytes() 2011-11-17 11:42:54 -02:00
clk
clocksource Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
connector
cpufreq [CPUFREQ] db8500: fix build error due to undeclared i variable 2011-11-11 22:28:33 -05:00
cpuidle Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2011-11-07 10:13:52 -08:00
crypto Merge git://github.com/herbertx/crypto 2011-11-25 21:55:07 -08:00
dca
devfreq PM / devfreq: correct Kconfig dependency 2011-11-14 23:31:35 +01:00
dio
dma Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
edac drivers/edac/mpc85xx_edac.c: fix memory controller compatible for edac 2011-11-24 01:59:38 -06:00
eisa
firewire Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
firmware Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound 2011-12-02 08:10:51 -08:00
gpio gpio: fix a build failure on KS8695 GPIO 2011-12-05 15:30:33 -08:00
gpu vmwgfx: integer overflow in vmw_kms_update_layout_ioctl() 2011-12-02 10:49:41 +00:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2011-12-02 08:25:46 -08:00
hv
hwmon hwmon: convert drivers/hwmon/* to use module_platform_driver() 2011-11-26 09:48:20 -08:00
hwspinlock Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-08 18:34:16 -08:00
i2c Merge branch 'fixes' of http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm 2011-12-01 11:53:54 -08:00
ide Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide 2011-11-18 22:04:12 -02:00
idle Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2011-11-07 10:13:52 -08:00
ieee802154 net: remove NETIF_F_NO_CSUM feature bit 2011-11-16 17:43:12 -05:00
infiniband infiniband: ipoib: Sanitize neighbour handling in ipoib_main.c 2011-12-05 15:20:20 -05:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-11-22 09:18:06 -08:00
iommu intr_remapping: Fix section mismatch in ir_dev_scope_init() 2011-12-05 18:22:53 +01:00
isdn Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-02 13:49:21 -05:00
leds Revert "leds: save the delay values after a successful call to blink_set()" 2011-11-15 22:41:50 -02:00
lguest enable virtio_net to return bus_info in ethtool -i consistent with emulated NICs 2011-11-16 17:26:46 -05:00
macintosh m68k/irq: Remove obsolete IRQ_FLG_* users 2011-11-08 22:35:48 +01:00
mca
md md/raid5: STRIPE_ACTIVE has lock semantics, add barriers 2011-11-08 16:22:06 +11:00
media Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2011-11-12 00:03:50 -02:00
memstick
message
mfd mfd: fix build failures in recently added ab5500 code 2011-11-07 21:45:14 -05:00
misc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-02 13:49:21 -05:00
mmc arm/imx: fix imx6q mmc error when mounting rootfs 2011-11-11 16:53:35 +01:00
mtd MTD: MAPS: bcm963xx-flash.c: explicitly include module.h 2011-11-07 21:26:55 -05:00
net xen-netfront: delay gARP until backend switches to Connected 2011-12-12 19:02:41 -05:00
nfc NFC: pn533: Staticise pn533_data_exchange() 2011-11-30 15:09:00 -05:00
nubus
of of/irq: of_irq_init: add check for parent equal to child node 2011-11-29 08:22:40 -06:00
oprofile Merge branch 'urgent' of git://amd64.org/linux/rric into perf/urgent 2011-11-15 11:03:30 +01:00
parisc
parport
pci Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2011-11-23 14:58:46 -08:00
pcmcia Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
pinctrl pinctrl: hide subsystem from the populace 2011-11-10 09:02:12 +01:00
platform toshiba_acpi: Fix machines that don't support HCI_SYSTEM_EVENT 2011-12-05 13:07:28 -05:00
pnp Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2011-11-07 10:13:52 -08:00
power x86/mrst: Battery fixes 2011-12-05 17:06:37 +01:00
pps
ps3 powerpc/ps3: irq: Remove IRQF_DISABLED 2011-11-08 14:51:46 +11:00
ptp
rapidio Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
regulator regulator: twl: fix twl4030 support for smps regulators 2011-11-28 18:58:31 +00:00
rtc Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2011-12-05 16:53:43 -08:00
s390 net: make vlan ndo_vlan_rx_[add/kill]_vid return error value 2011-12-08 19:52:37 -05:00
sbus
scsi cxgb4i: Handle dst_get_neighbour_noref() returning NULL. 2011-12-05 15:20:20 -05:00
sfi
sh Merge branches 'sh/pm-runtime' and 'common/clkfwk' into sh-fixes-for-linus 2011-11-11 16:16:25 +09:00
sn
spi ARM: 7175/1: add subname parameter to mfp_set_groupg callers 2011-11-26 21:58:54 +00:00
ssb
staging Merge branch 'staging-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging 2011-12-02 13:30:25 -08:00
target Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
tc
telephony
thermal thermal: Prevent polling from happening during system suspend 2011-11-06 20:38:49 -05:00
tty Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty 2011-11-21 20:36:46 -08:00
uio
usb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-06 21:10:05 -05:00
uwb
vhost
video viafb: correct sync polarity for OLPC DCON 2011-11-22 00:56:17 +00:00
virt
virtio Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-02 13:49:21 -05:00
vlynq
w1 Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
watchdog watchdog: fix initialisation printout in s3c2410_wdt 2011-11-16 22:04:17 +01:00
xen xen-gntalloc: signedness bug in add_grefs() 2011-11-16 12:13:48 -05:00
zorro
Kconfig
Makefile