When xen_emul_unplug=never is specified on kernel command line
reading files from /sys/hypervisor is broken (returns -EBUSY).
It is caused by xen_bus dependency on platform-pci and
platform-pci isn't initialized when xen_emul_unplug=never is
specified.

Fix it by allowing platform-pci to ignore xen_emul_unplug=never,
and do not intialize xen_[blk|net]front instead.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The 'name', 'owner', and 'mod_name' members are redundant with the
identically named fields in the 'driver' sub-structure. Rather than
switching each instance to specify these fields explicitly, introduce
a macro to simplify this.

Eliminate further redundancy by allowing the drvname argument to
DEFINE_XENBUS_DRIVER() to be blank (in which case the first entry from
the ID table will be used for .driver.name).

Also eliminate the questionable xenbus_register_{back,front}end()
wrappers - their sole remaining purpose was the checking of the
'owner' field, proper setting of which shouldn't be an issue anymore
when the macro gets used.

v2: Restore DRV_NAME for the driver name in xen-pciback.
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

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 f942dc25 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.htmlSigned-off-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Save some punctuation by using bool type's property equivalent to
doubled negation operator.
Reported-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

v2:	add couple missing conversions in drivers
	split unexporting netdev_fix_features()
	implemented %pNF
	convert sock::sk_route_(no?)caps
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

To ease skb->truesize sanitization, its better to be able to localize
all references to skb frags size.

Define accessors : skb_frag_size() to fetch frag size, and
skb_frag_size_{set|add|sub}() to manipulate it.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xensource.com
Cc: netdev@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Convert xen driver to 64 bit statistics interface.
Use stats_sync to ensure that 64 bit update is read atomically on 32 bit platform.
Put hot statistics into per-cpu table.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Konrad reports:
[    0.930811] RTNL: assertion failed at /home/konrad/ssd/linux/net/core/dev.c (5258)
[    0.930821] Pid: 22, comm: xenwatch Not tainted 2.6.39-05193-gd762f438 #1
[    0.930825] Call Trace:
[    0.930834]  [<ffffffff8143bd0e>] __netdev_update_features+0xae/0xe0
[    0.930840]  [<ffffffff8143dd41>] netdev_update_features+0x11/0x30
[    0.930847]  [<ffffffffa0037105>] netback_changed+0x4e5/0x800 [xen_netfront]
[    0.930854]  [<ffffffff8132a838>] xenbus_otherend_changed+0xa8/0xb0
[    0.930860]  [<ffffffff8157ca99>] ? _raw_spin_unlock_irqrestore+0x19/0x20
[    0.930866]  [<ffffffff8132adfe>] backend_changed+0xe/0x10
[    0.930871]  [<ffffffff8132875a>] xenwatch_thread+0xba/0x180
[    0.930876]  [<ffffffff810a8ba0>] ? wake_up_bit+0x40/0x40
[    0.930881]  [<ffffffff813286a0>] ? split+0xf0/0xf0
[    0.930886]  [<ffffffff810a8646>] kthread+0x96/0xa0
[    0.930891]  [<ffffffff815855a4>] kernel_thread_helper+0x4/0x10
[    0.930896]  [<ffffffff815846b3>] ? int_ret_from_sys_call+0x7/0x1b
[    0.930901]  [<ffffffff8157cf61>] ? retint_restore_args+0x5/0x6
[    0.930906]  [<ffffffff815855a0>] ? gs_change+0x13/0x13

This update happens in xenbus watch callback context and hence does not already
hold the rtnl. Take the lock as necessary.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Tested-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We need to assume that all features will be available when registering the
netdev otherwise they are ommitted from the initial set of
dev->wanted_features. When we connect to the backed we reduce the set as
necessary due to the call to netdev_update_features() in xennet_connect().
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Must declare xennet_fix_features() and xennet_set_features() before
using them.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Not tested in any way. The original code for offload setting seems broken
as it resets the features on every netback reconnect.

This will set GSO_ROBUST at device creation time (earlier than connect time).

RX checksum offload is forced on - so advertise as it is.
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The IRQF_SAMPLE_RANDOM flag is marked as deprecated and will be removed.

Every input point to the kernel's entropy pool have to better document the
type of entropy source it is.

drivers/char/random.c now implements a set of interfaces that can be used for
devices to collect enviromental noise. IRQF_SAMPLE_RANDOM will be replaced
with these add_*_randomness exported functions.

Network drivers are not a good source of entropy. They use as a source of
entropy essentially a remote host. Which means that the source of entropy can
be potentially controlled by an attacker. Also, with heavy workloads the
entropy decreases due to less hardware interrupts happening thanks to irq
mitigation and NAPI.

If a system relies in its network interface as a entropy source it has a false
sense of security. Systems that don't have devices whose drivers are good
sources of entropy, should either use a hardware random number generator or
feed the kernel's entropy pool from userspace using other sources of entropy
such as EGD, video_entropyd, timer_entropyd and audio-entropyd.
Signed-off-by: NJavier Martinez Canillas <martinez.javier@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

netback is the host side counterpart to the frontend driver in
drivers/net/xen-netfront.c. The PV protocol is also implemented by
frontend drivers in other OSes too, such as the BSDs and even Windows.

The patch is based on the driver from the xen.git pvops kernel tree but
has been put through the checkpatch.pl wringer plus several manual
cleanup passes and review iterations. The driver has been moved from
drivers/xen/netback to drivers/net/xen-netback.

One major change from xen.git is that the guest transmit path (i.e. what
looks like receive to netback) has been significantly reworked to remove
the dependency on the out of tree PageForeign page flag (a core kernel
patch which enables a per page destructor callback on the final
put_page). This page flag was used in order to implement a grant map
based transmit path (where guest pages are mapped directly into SKB
frags). Instead this version of netback uses grant copy operations into
regular memory belonging to the backend domain. Reinstating the grant
map functionality is something which I would like to revisit in the
future.

Note that this driver depends on 2e820f58 "xen/irq: implement
bind_interdomain_evtchn_to_irqhandler for backend drivers" which is in
linux next via the "xen-two" tree and is intended for the 2.6.39 merge
window:
        git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/backends
this branch has only that single commit since 2.6.38-rc2 and is safe for
cross merging into the net branch.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Reviewed-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit e9a799ea (xen: netfront: ethtool stats fields should be
unsigned long) made rx_gso_checksum_fixup an unsigned long.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixup the rx_gso_checksum_fixup field added in e0ce4af9 to be
unsigned long as suggested by Ben Hutchings in
<1298919198.2569.14.camel@bwh-desktop>
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The Linux network stack expects all GSO SKBs to have ip_summed ==
CHECKSUM_PARTIAL (which implies that the frame contains a partial
checksum) and the Xen network ring protocol similarly expects an SKB
which has GSO set to also have NETRX_csum_blank (which also implies a
partial checksum).

However there have been cases of buggy guests which mark a frame as
GSO but do not set csum_blank. If we detect that we a receiving such a
frame (which manifests as ip_summed != PARTIAL && skb_is_gso) then
force the SKB to partial and recalculate the checksum, since we cannot
rely on the peer having done so if they have not set csum_blank.

Add an ethtool stat to track occurances of this event.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Miller <davem@davemloft.net>
Cc: xen-devel@lists.xensource.com
Cc: netdev@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that there is a single function that can compute the device
features relevant to a packet, we don't want to run it for each
offload.  This converts netif_needs_gso() to take the features
of the device, rather than computing them itself.
Signed-off-by: NJesse Gross <jesse@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Without this, gcc 4.5 won't compile xen-netfront and xen-blkfront, where
this is being used to specify array sizes.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Miller <davem@davemloft.net>
Cc: Stable Kernel <stable@kernel.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

XenbusStateReconfiguring/XenbusStateReconfigured were introduced by
c/s 437, but aren't handled in many switch statements.

.. also pulled from the linux-2.6-sparse-tree tree.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Change "return (EXPR);" to "return EXPR;"

return is not a function, parentheses are not required.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

All Xen frontend drivers have a couple of identically named functions which
makes figuring out which device went wrong from a stacktrace harder than it
needs to be. Rename them to something specificto the device type.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use newly introduced netif_notify_peers() method to ensure a gratuitous ARP is
generated after a migration.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: xen-devel@lists.xensource.com
Cc: stable@kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

Move xen_domain and related tests out of asm-x86 to xen/xen.h so they
can be included whenever they are necessary.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

No need to put ethtool_ops in data, they should be const.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch is the result of an automatic spatch transformation to convert
all ndo_start_xmit() return values of 0 to NETDEV_TX_OK.

Some occurences are missed by the automatic conversion, those will be
handled in a seperate patch.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the near future, the driver core is going to not allow direct access
to the driver_data pointer in struct device.  Instead, the functions
dev_get_drvdata() and dev_set_drvdata() should be used.  These functions
have been around since the beginning, so are backwards compatible with
all older kernel versions.

Cc: xen-devel@lists.xensource.com
Cc: virtualization@lists.osdl.org
Acked-by: NChris Wright <chrisw@sous-sol.org>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Reclaim 8 upper bits of netdev->features from GSO.
Signed-off-by: NChris Leech <christopher.leech@intel.com>
Signed-off-by: NYi Zou <yi.zou@intel.com>
Acked-by: NDavid Miller <davem@davemloft.net>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

Following the removal of the unused struct net_device * parameter from
the NAPI functions named *netif_rx_* in commit 908a7a16, they are
exactly equivalent to the corresponding *napi_* functions and are
therefore redundant.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Convert Xen device to new API.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the napi api was changed to separate its 1:1 binding to the net_device
struct, the netif_rx_[prep|schedule|complete] api failed to remove the now
vestigual net_device structure parameter.  This patch cleans up that api by
properly removing it..
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

... by giving the instances' names magic suffix recognized by modpost ;-/
Their ->probe() is __devinit
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The generic packet receive code takes care of setting
netdev->last_rx when necessary, for the sake of the
bonding ARP monitor.

Drivers need not do it any more.

Some cases had to be skipped over because the drivers
were making use of the ->last_rx value themselves.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
(d)) but is perhaps more readable.

An extract of the semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@haskernel@
@@

#include <linux/kernel.h>

@depends on haskernel@
expression n,d;
@@

(
- (n + d - 1) / d
+ DIV_ROUND_UP(n,d)
|
- (n + (d - 1)) / d
+ DIV_ROUND_UP(n,d)
)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP((n),d)
+ DIV_ROUND_UP(n,d)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP(n,(d))
+ DIV_ROUND_UP(n,d)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Acked-by: NJeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Align ip header to a 16 byte boundary to avoid unaligned
access like other drivers.
Without this patch, xen-netfront doesn't work well on ia64.
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

There are four operating modes Xen code may find itself running in:
 - native
 - hvm domain
 - pv dom0
 - pv domU

Clean up predicates for testing for these states to make them more consistent.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Xen-devel <xen-devel@lists.xensource.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

xen-netfront never called netif_start_queue() and was was waking the
queue on xennet_open(), triggering the BUG_ON() on __netif_schedule().
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

After restore on ia64 xen domain, kernel panics as follows.
This patch fixes it.

union skb_entry assumes sizeof(link->skb, pointer) ==
sizeof(list->link, unsigned).
However this isn't true on ia64. So  make link type unsigned long.
And introduced two accesor.

kernel unaligned access to 0xe0000000000000bd, ip=0xa0000001004c2ca0
xenwatch[14]: error during unaligned kernel access
 -1 [1]
Modules linked in:

Pid: 14, CPU 0, comm:             xenwatch
psr : 0000101008422010 ifs : 8000000000000307 ip  : [<a0000001004c2ca0>]    Not tainted (2.6.26-rc4xen-ia64-dirty)
ip is at dev_kfree_skb_irq+0x20/0x1a0
unat: 0000000000000000 pfs : 400000000000040b rsc : 0000000000000007
rnat: 0000000000000000 bsps: 0000000000000000 pr  : 000000000000a941
ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c8a70433f
csd : 0000000000000000 ssd : 0000000000000000
b0  : a0000001003efb70 b6  : a000000100070e40 b7  : a000000100070e40
f6  : 1003e000000fcb75352b1 f7  : 1003e000000000014ff97
f8  : 1003e00fcb74fc3454d80 f9  : 1003e0000000080000000
f10 : 1003e0000000000001431 f11 : 1003e0000000000989680
r1  : a000000100bfcf80 r2  : e0000000000000bd r3  : 000000000000308c
r8  : 0000000000000000 r9  : e00000000fc31310 r10 : a000000100a13b28
r11 : 0000000000000000 r12 : e00000000fd0fdf0 r13 : e00000000fd08000
r14 : 0000000000000000 r15 : e00000000fcc8000 r16 : 0000000000000009
r17 : e000010000104000 r18 : e000010000104000 r19 : a000000100a13b40
r20 : a0000001009c23f0 r21 : a0000001009fd4d0 r22 : 0000000000004000
r23 : 0000000000000000 r24 : fffffffffff04c10 r25 : 0000000000000002
r26 : 0000000000000000 r27 : 0000000000000000 r28 : e00000000fd08bd4
r29 : a0000001007570b8 r30 : a0000001009e5500 r31 : a0000001009e54a0

Call Trace:
 [<a000000100026000>] show_stack+0x40/0xa0
                                sp=e00000000fd0f670 bsp=e00000000fd08f68
 [<a000000100026a60>] show_regs+0x9a0/0x9e0
                                sp=e00000000fd0f840 bsp=e00000000fd08f10
 [<a000000100037680>] die+0x260/0x3a0
                                sp=e00000000fd0f840 bsp=e00000000fd08ec8
 [<a000000100037810>] die_if_kernel+0x50/0x80
                                sp=e00000000fd0f840 bsp=e00000000fd08e98
 [<a00000010003eb40>] ia64_handle_unaligned+0x2ea0/0x2fc0
                                sp=e00000000fd0f840 bsp=e00000000fd08df0
 [<a00000010001ca30>] ia64_prepare_handle_unaligned+0x30/0x60
                                sp=e00000000fd0fa10 bsp=e00000000fd08df0
 [<a00000010005d100>] paravirt_leave_kernel+0x0/0x40
                                sp=e00000000fd0fc20 bsp=e00000000fd08df0
 [<a0000001004c2ca0>] dev_kfree_skb_irq+0x20/0x1a0
                                sp=e00000000fd0fdf0 bsp=e00000000fd08db8
 [<a0000001003efb70>] xennet_release_tx_bufs+0xd0/0x120
                                sp=e00000000fd0fdf0 bsp=e00000000fd08d78
 [<a0000001003f14c0>] backend_changed+0xc40/0xf80
                                sp=e00000000fd0fdf0 bsp=e00000000fd08d08
 [<a00000010034bd50>] otherend_changed+0x190/0x1c0
                                sp=e00000000fd0fe00 bsp=e00000000fd08cc8
 [<a000000100349530>] xenwatch_thread+0x310/0x3c0
                                sp=e00000000fd0fe00 bsp=e00000000fd08ca0
 [<a0000001000cb040>] kthread+0xe0/0x160
                                sp=e00000000fd0fe30 bsp=e00000000fd08c68
 [<a000000100024450>] kernel_thread_helper+0x30/0x60
                                sp=e00000000fd0fe30 bsp=e00000000fd08c40
 [<a00000010001a8a0>] start_kernel_thread+0x20/0x40
                                sp=e00000000fd0fe30 bsp=e00000000fd08c40
Kernel panic - not syncing: Aiee, killing interrupt handler!
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Avoid allocations causing swap activity on the resume path by
preventing the allocations from doing IO and allowing them
to access the emergency pools.

These paths are used when a frontend device is trying to connect
to its backend driver over Xenbus.  These reconnections are triggered
on demand by IO, so by definition there is already IO underway,
and further IO would naturally deadlock.  On resume, this path
is triggered when the running system tries to continue using its
devices.  If it cannot then the resume will fail; to try to avoid this
we let it dip into the emergency pools.

[ linux-2.6.18-xen changesets e8b49cfbdac, fdb998e79aba ]
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>