this patch fixes following sparse warning:

interface.c:83:5: warning: symbol 'xenvif_poll' was not declared. Should it be static?
Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After commit e9d8b2c2 (xen-netback:
disable rogue vif in kthread context), a fatal (protocol) error would
leave the guest Rx thread spinning, wasting CPU time.  Commit
ecf08d2d (xen-netback: reintroduce
guest Rx stall detection) made this even worse by removing a
cond_resched() from this path.

Since a fatal error is non-recoverable, just allow the guest Rx thread
to exit.  This requires taking additional refs to the task so the
thread exiting early is handled safely.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Reported-by: NJulien Grall <julien.grall@linaro.org>
Tested-by: NJulien Grall <julien.grall@linaro.org>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the foreign page flag in netback to get the domid and grant ref
needed for the grant copy.  This signficiantly simplifies the netback
code and makes netback work with foreign pages from other backends
(e.g., blkback).

This allows blkback to use iSCSI disks provided by domUs running on
the same host.
Signed-off-by: NJennifer Herbert <jennifer.herbert@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Add gnttab_alloc_pages() and gnttab_free_pages() to allocate/free pages
suitable to for granted maps.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

Ballooned pages are always used for grant maps which means the
original frame does not need to be saved in page->index nor restored
after the grant unmap.

This allows the workaround in netback for the conflicting use of the
(unionized) page->index and page->pfmemalloc to be removed.
Signed-off-by: NJennifer Herbert <jennifer.herbert@citrix.com>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Always fully coalesce guest Rx packets into the minimum number of ring
slots.  Reducing the number of slots per packet has significant
performance benefits when receiving off-host traffic.

Results from XenServer's performance benchmarks:

                         Baseline    Full coalesce
Interhost VM receive      7.2 Gb/s   11 Gb/s
Interhost aggregate      24 Gb/s     24 Gb/s
Intrahost single stream  14 Gb/s     14 Gb/s
Intrahost aggregate      34 Gb/s     34 Gb/s

However, this can increase the number of grant ops per packet which
decreases performance of backend (dom0) to VM traffic (by ~10%)
/unless/ grant copy has been optimized for adjacent ops with the same
source or destination (see "grant-table: defer releasing pages
acquired in a grant copy"[1] expected in Xen 4.6).

[1] http://lists.xen.org/archives/html/xen-devel/2015-01/msg01118.htmlSigned-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since e9ce7cb6 ("xen-netback: Factor queue-specific data into queue struct"),
the transimt shaper timeout is always set to 0.  The value the user sets via
xenbus is never propagated to the transmit shaper.

This patch fixes the issue.

Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: NImre Palik <imrep@amazon.de>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit bc96f648 (xen-netback: make
feature-rx-notify mandatory) incorrectly assumed that there were no
frontends in use that did not support this feature.  But the frontend
driver in MiniOS does not and since this is used by (qemu) stubdoms,
these stopped working.

Netback sort of works as-is in this mode except:

- If there are no Rx requests and the internal Rx queue fills, only
  the drain timeout will wake the thread.  The default drain timeout
  of 10 s would give unacceptable pauses.

- If an Rx stall was detected and the internal Rx queue is drained,
  then the Rx thread would never wake.

Handle these two cases (when feature-rx-notify is disabled) by:

- Reducing the drain timeout to 30 ms.

- Disabling Rx stall detection.
Reported-by: NJohn <jw@nuclearfallout.net>
Tested-by: NJohn <jw@nuclearfallout.net>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When xenvif_alloc() fails, it returns a non-NULL error indicator. To
avoid eventual races, we shouldn't store that into struct backend_info
as readers of it only check for NULL.
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If xenvif_alloc() or xenbus_scanf() fail in backend_create_xenvif(),
xenbus is left in offline mode but netback_probe() reports success.

The patch implements propagation of error code for backend_create_xenvif().

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Unconditionally pulling 128 bytes into the linear area is not required
for:

- security: Every protocol demux starts with pskb_may_pull() to pull
  frag data into the linear area, if necessary, before looking at
  headers.

- performance: Netback has already grant copied up-to 128 bytes from
  the first slot of a packet into the linear area. The first slot
  normally contain all the IPv4/IPv6 and TCP/UDP headers.

The unconditional pull would often copy frag data unnecessarily.  This
is a performance problem when running on a version of Xen where grant
unmap avoids TLB flushes for pages which are not accessed.  TLB
flushes can now be avoided for > 99% of unmaps (it was 0% before).

Grant unmap TLB flush avoidance will be available in a future version
of Xen (probably 4.6).
Signed-off-by: NMalcolm Crossley <malcolm.crossley@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This flag is unnecessary, it came from some old code.
Suggested-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NZoltan Kiss <zoltan.kiss@linaro.org>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Otherwise the interrupt handler still calls napi_complete. Although it
won't schedule NAPI again as either NAPI_STATE_DISABLE or
NAPI_STATE_SCHED is set, it is just unnecessary, and it makes more
sense to do this way.
Signed-off-by: NZoltan Kiss <zoltan.kiss@linaro.org>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If a frontend not receiving packets it is useful to detect this and
turn off the carrier so packets are dropped early instead of being
queued and drained when they expire.

A to-guest queue is stalled if it doesn't have enough free slots for a
an extended period of time (default 60 s).

If at least one queue is stalled, the carrier is turned off (in the
expectation that the other queues will soon stall as well).  The
carrier is only turned on once all queues are ready.

When the frontend connects, all the queues start in the stalled state
and only become ready once the frontend queues enough Rx requests.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Netback needs to discard old to-guest skb's (guest Rx queue drain) and
it needs detect guest Rx stalls (to disable the carrier so packets are
discarded earlier), but the current implementation is very broken.

1. The check in hard_start_xmit of the slot availability did not
   consider the number of packets that were already in the guest Rx
   queue.  This could allow the queue to grow without bound.

   The guest stops consuming packets and the ring was allowed to fill
   leaving S slot free.  Netback queues a packet requiring more than S
   slots (ensuring that the ring stays with S slots free).  Netback
   queue indefinately packets provided that then require S or fewer
   slots.

2. The Rx stall detection is not triggered in this case since the
   (host) Tx queue is not stopped.

3. If the Tx queue is stopped and a guest Rx interrupt occurs, netback
   will consider this an Rx purge event which may result in it taking
   the carrier down unnecessarily.  It also considers a queue with
   only 1 slot free as unstalled (even though the next packet might
   not fit in this).

The internal guest Rx queue is limited by a byte length (to 512 Kib,
enough for half the ring).  The (host) Tx queue is stopped and started
based on this limit.  This sets an upper bound on the amount of memory
used by packets on the internal queue.

This allows the estimatation of the number of slots for an skb to be
removed (it wasn't a very good estimate anyway).  Instead, the guest
Rx thread just waits for enough free slots for a maximum sized packet.

skbs queued on the internal queue have an 'expires' time (set to the
current time plus the drain timeout).  The guest Rx thread will detect
when the skb at the head of the queue has expired and discard expired
skbs.  This sets a clear upper bound on the length of time an skb can
be queued for.  For a guest being destroyed the maximum time needed to
wait for all the packets it sent to be dropped is still the drain
timeout (10 s) since it will not be sending new packets.

Rx stall detection is reintroduced in a later commit.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Frontends that do not provide feature-rx-notify may stall because
netback depends on the notification from frontend to wake the guest Rx
thread (even if can_queue is false).

This could be fixed but feature-rx-notify was introduced in 2006 and I
am not aware of any frontends that do not implement this.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The DEFINE_XENBUS_DRIVER() macro looks a bit weird and causes sparse
errors.

Replace the uses with standard structure definitions instead.  This is
similar to pci and usb device registration.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Interrupt is enabled when bind_interdomain_evtchn_to_irqhandler returns.
If there's interrupt pending interrupt handler is invoked.

NAPI needs to be initialised before binding interrupt otherwise the
interrupt handler will try to scheduling a NAPI instance that is not
initialised yet, resulting in kernel OOPS.

This fixes a regression introduced in ea2c5e13 ("xen-netback: move NAPI
add/remove calls").

Ideally function calls to create kthreads should also be moved before
binding but I intent to fix this regression with minimal changes and
refactor the code with another patch.
Reported-by: NThomas Leonard <talex5@gmail.com>
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The original implementation relies on a loop to check if all inflight
packets are freed. Now we have proper reference counting, there's no
need to use loop anymore.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Reference count the number of packets in host stack, so that we don't
stop the deallocation thread too early. If not, we can end up with
xenvif_free permanently waiting for deallocation thread to unmap grefs.
Reported-by: NThomas Leonard <talex5@gmail.com>
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Originally netif_napi_add was in xenvif_init_queue and netif_napi_del
was in xenvif_deinit_queue, while kthreads were handled in
xenvif_connect and xenvif_disconnect. Move netif_napi_add and
netif_napi_del to xenvif_connect and xenvif_disconnect so that they
reside together with kthread operations.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The original code is bogus. The function gets called in a loop which
leaks entries created in previous rounds.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Enlarge buffer size and check input length properly, so that we don't
misuse -ENOSPC.

Note that command like "kickXXXX" is still allowed, that's one patch for
another day if we really want to be very strict on this.
Reported-by: NSeeChen Ng <seechen81@gmail.com>
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the patch called "xen-netback: Turn off the carrier if the guest is not able
to receive" NAPI was descheduled when the carrier was set off. That's
not what most of the drivers do, and we don't have any specific reason to do so
as well, so revert that change.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the patch called "xen-netback: Turn off the carrier if the guest is not able
to receive" new branches were introduced to this if statement, risking that a
queue with non-zero id can reenable the disabled interface.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently when the guest is not able to receive more packets, qdisc layer starts
a timer, and when it goes off, qdisc is started again to deliver a packet again.
This is a very slow way to drain the queues, consumes unnecessary resources and
slows down other guests shutdown.
This patch change the behaviour by turning the carrier off when that timer
fires, so all the packets are freed up which were stucked waiting for that vif.
Instead of the rx_queue_purge bool it uses the VIF_STATUS_RX_PURGE_EVENT bit to
signal the thread that either the timeout happened or an RX interrupt arrived,
so the thread can check what it should do. It also disables NAPI, so the guest
can't transmit, but leaves the interrupts on, so it can resurrect.
Only the queues which brought down the interface can enable it again, the bit
QUEUE_STATUS_RX_STALLED makes sure of that.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces a new state bit VIF_STATUS_CONNECTED to track whether the
vif is in a connected state. Using carrier will not work with the next patch
in this series, which aims to turn the carrier temporarily off if the guest
doesn't seem to be able to receive packets.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org

v2:
- rename the bitshift type to "enum state_bit_shift" here, not in the next patch
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Due to this pointer is increased prematurely, the error log contains rubbish.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Reported-by: NArmin Zentai <armin.zentai@ezit.hu>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch makes this function aware that the first frag and the header might
share the same ring slot. That could happen if the first slot is bigger than
PKT_PROT_LEN. Due to this the error path might release that slot twice or never,
depending on the error scenario.
xenvif_idx_release is also removed from xenvif_idx_unmap, and called separately.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Reported-by: NArmin Zentai <armin.zentai@ezit.hu>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the grant operations failed, the skb is freed up eventually, and it tries
to release the frags, if there is any. For the main skb nr_frags is set to 0 to
avoid this, but on the frag_list it iterates through the frags array, and tries
to call put_page on the page pointer which contains garbage at that time.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Reported-by: NArmin Zentai <armin.zentai@ezit.hu>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The error handling for skb's with frag_list was completely wrong, it caused
double unmap attempts to happen if the error was on the first skb. Move it to
the right place in the loop.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Reported-by: NArmin Zentai <armin.zentai@ezit.hu>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Extend alloc_netdev{,_mq{,s}}() to take name_assign_type as argument, and convert
all users to pass NET_NAME_UNKNOWN.

Coccinelle patch:

@@
expression sizeof_priv, name, setup, txqs, rxqs, count;
@@

(
-alloc_netdev_mqs(sizeof_priv, name, setup, txqs, rxqs)
+alloc_netdev_mqs(sizeof_priv, name, NET_NAME_UNKNOWN, setup, txqs, rxqs)
|
-alloc_netdev_mq(sizeof_priv, name, setup, count)
+alloc_netdev_mq(sizeof_priv, name, NET_NAME_UNKNOWN, setup, count)
|
-alloc_netdev(sizeof_priv, name, setup)
+alloc_netdev(sizeof_priv, name, NET_NAME_UNKNOWN, setup)
)

v9: move comments here from the wrong commit
Signed-off-by: NTom Gundersen <teg@jklm.no>
Reviewed-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds debugfs capabilities to netback. There used to be a similar
patch floating around for classic kernel, but it used procfs. It is based on a
very similar blkback patch.
It creates xen-netback/[vifname]/io_ring_q[queueno] files, reading them output
various ring variables etc. Writing "kick" into it imitates an interrupt
happened, it can be useful to check whether the ring is just stalled due to a
missed interrupt.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The original code uses netdev->real_num_tx_queues to bookkeep number of
queues and invokes netif_set_real_num_tx_queues to set the number of
queues. However, netif_set_real_num_tx_queues doesn't allow
real_num_tx_queues to be smaller than 1, which means setting the number
to 0 will not work and real_num_tx_queues is untouched.

This is bogus when xenvif_free is invoked before any number of queues is
allocated. That function needs to iterate through all queues to free
resources. Using the wrong number of queues results in NULL pointer
dereference.

So we bookkeep the number of queues in xen-netback to solve this
problem. This fixes a regression introduced by multiqueue patchset in
3.16-rc1.

There's another bug in original code that the real number of RX queues
is never set. In current Xen multiqueue design, the number of TX queues
and RX queues are in fact the same. We need to set the numbers of TX and
RX queues to the same value.

Also remove xenvif_select_queue and leave queue selection to core
driver, as suggested by David Miller.
Reported-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
CC: Ian Campbell <ian.campbell@citrix.com>
CC: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit e9ce7cb6 ("xen-netback: Factor queue-specific data into
queue struct") added a use of vzalloc/vfree to interface.c, but
removed the #include <linux/vmalloc.h> statement at the same time,
which causes this build error:

drivers/net/xen-netback/interface.c: In function 'xenvif_free':
drivers/net/xen-netback/interface.c:754:2: error: implicit declaration of function 'vfree' [-Werror=implicit-function-declaration]
  vfree(vif->queues);
  ^
cc1: some warnings being treated as errors
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Andrew J. Bennieston <andrew.bennieston@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A recent commit (a02eb4 "xen-netback: worse-case estimate in xenvif_rx_action is
underestimating") capped the slot estimation to MAX_SKB_FRAGS, but that triggers
the next BUG_ON a few lines down, as the packet consumes more slots than
estimated.
This patch introduces full_coalesce on the skb callback buffer, which is used in
start_new_rx_buffer() to decide whether netback needs coalescing more
aggresively. By doing that, no packet should need more than
(XEN_NETIF_MAX_TX_SIZE + 1) / PAGE_SIZE data slots (excluding the optional GSO
slot, it doesn't carry data, therefore irrelevant in this case), as the provided
buffers are fully utilized.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: NPaul Durrant <paul.durrant@gmail.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Builds on the refactoring of the previous patch to implement multiple
queues between xen-netfront and xen-netback.

Writes the maximum supported number of queues into XenStore, and reads
the values written by the frontend to determine how many queues to use.

Ring references and event channels are read from XenStore on a per-queue
basis and rings are connected accordingly.

Also adds code to handle the cleanup of any already initialised queues
if the initialisation of a subsequent queue fails.
Signed-off-by: NAndrew J. Bennieston <andrew.bennieston@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In preparation for multi-queue support in xen-netback, move the
queue-specific data from struct xenvif into struct xenvif_queue, and
update the rest of the code to use this.

Also adds loops over queues where appropriate, even though only one is
configured at this point, and uses alloc_netdev_mq() and the
corresponding multi-queue netif wake/start/stop functions in preparation
for multiple active queues.

Finally, implements a trivial queue selection function suitable for
ndo_select_queue, which simply returns 0 for a single queue and uses
skb_get_hash() to compute the queue index otherwise.
Signed-off-by: NAndrew J. Bennieston <andrew.bennieston@citrix.com>
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This array was allocated separately in commit ac3d5ac2 ("xen-netback:
fix guest-receive-side array sizes") due to it being very large, and a
struct xenvif is allocated as the netdev_priv part of a struct
net_device, i.e. via kmalloc() but falling back to vmalloc() if the
initial alloc. fails.

In preparation for the multi-queue patches, where this array becomes
part of struct xenvif_queue and is always allocated through vzalloc(),
move this back into the struct xenvif.
Signed-off-by: NAndrew J. Bennieston <andrew.bennieston@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the NAPI budget was not all used, xenvif_poll() would call
napi_complete() /after/ enabling the interrupt.  This resulted in a
race between the napi_complete() and the napi_schedule() in the
interrupt handler.  The use of local_irq_save/restore() avoided by
race iff the handler is running on the same CPU but not if it was
running on a different CPU.

Fix this properly by calling napi_complete() before reenabling
interrupts (in the xenvif_napi_schedule_or_enable_irq() call).
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>