The code was polling the firmware tail register for completion every
10 microseconds, which is way faster than the firmware can respond.
This changes the poll interval to 1ms, which reduces polling CPU
utilization, and the number of times we loop.

The maximum delay is still 100ms.

Change-ID: I4bbfa6b66d802890baf8b4154061e55942b90958
Signed-off-by: Kamil Krawczyk <kamil.krawczyk@intel.com>
Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

After commit 1a288172 ("mlx4: use napi_complete_done()") we ended up
calling napi_complete_done() in the case NAPI poll consumed all its
budget.

This added extra interrupt pressure, this patch restores proper
behavior.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 1a288172 ("mlx4: use napi_complete_done()")
Signed-off-by: David S. Miller <davem@davemloft.net>

Sowmini Varadhan says:

====================
sunvnet: edge-case/race-conditions bug fixes

This patch series contains fixes for race-conditions in sunvnet,
that can encountered when there is a difference in latency between
producer and consumer.

Patch 1 addresses a case when the STOPPED LDC ack from a peer is
processed before vnet_start_xmit can finish updating the dr->prod
state.

Patch 2 fixes the edge-case when outgoing data and incoming
stopped-ack cross each other in flight.

Patch 3 adds a missing rcu_read_unlock(), found by code-inspection.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The out_dropped label will only do rcu_read_unlock for non-null port.
So add the missing rcu_read_unlock() when bailing due to non-null port.
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

As per comments in vnet_start_xmit, for the edge case
when outgoing vnet_start_xmit() data and an incoming STOPPED
ACK cross each other in flight, we may need to send the missed
START trigger from maybe_tx_wakeup() after checking for a
false value of start_cons
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When vnet_start_xmit() is concurrent with vnet_ack(), we may
have a race that looks like:

    thread 1                              thread 2
    vnet_start_xmit                       vnet_event_napi -> vnet_rx

__vnet_tx_trigger for some desc X
at this point dr->prod == X
                                        peer sends back a stopped ack for X
                                        we process X, but X == dr->prod
                                        so we bail out in vnet_ack with
                                        !idx_is_pending
update dr->prod

As a result of the fact that we never processed the stopped ack for X,
the Tx path is led to incorrectly believe that the peer is still
"started" and reading, but the peer has stopped reading, which will
ultimately end in flow-control assertions.

The fix is to synchronize the above 2 paths  on the netif_tx_lock.
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This driver allows MTU up to 1518 bytes which is not enought to run
batman-adv. Simply raise the maximum packet size up to the maximum
allowed by the transmit descriptor, 1792 bytes, giving a maximum MTU
of 1774 bytes.
Signed-off-by: Alban Bedel <albeu@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

Replace the default ndo_change_mtu callback with one that allow
setting MTU that the driver can handle.
Signed-off-by: Alban Bedel <albeu@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'master-2014-11-04' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next

John W. Linville says:

====================
pull request: wireless-next 2014-11-07

Please pull this batch of updates intended for the 3.19 stream!

For the mac80211 bits, Johannes says:

"This relatively large batch of changes is comprised of the following:
 * large mac80211-hwsim changes from Ben, Jukka and a bit myself
 * OCB/WAVE/11p support from Rostislav on behalf of the Czech Technical
   University in Prague and Volkswagen Group Research
 * minstrel VHT work from Karl
 * more CSA work from Luca
 * WMM admission control support in mac80211 (myself)
 * various smaller fixes, spelling corrections, and minor API additions"

For the Bluetooth bits, Johan says:

"Here's the first bluetooth-next pull request for 3.19. The vast majority
of patches are for ieee802154 from Alexander Aring with various fixes
and cleanups. There are also several LE/SMP fixes as well as improved
support for handling LE devices that have lost their pairing information
(the patches from Alfonso). Jukka provides a couple of stability fixes
for 6lowpan and Szymon conformance fixes for RFCOMM. For the HCI drivers
we have one new USB ID for an Acer controller as well as a reset
handling fix for H5."

For the Atheros bits, Kalle says:

"Major changes are:

o ethtool support (Ben)

o print dev string prefix with debug hex buffers dump (Michal)

o debugfs file to read calibration data from the firmware verification
  purposes (me)

o fix fw_stats debugfs file, now results are more reliable (Michal)

o firmware crash counters via debugfs (Ben&me)

o various tracing points to debug firmware (Rajkumar)

o make it possible to provide firmware calibration data via a file (me)

And we have quite a lot of smaller fixes and clean up."

For the iwlwifi bits, Emmanuel says:

"The big new thing here is netdetect which allows the
firmware to wake up the platform when a specific network
is detected. Along with that I have fixes for d3 operation.
The usual amount of rate scaling stuff - we now support STBC.
The other commit that stands out is Johannes's work on
devcoredump. He basically starts to use the standard
infrastructure he built."

Along with that are the usual sort of updates and such for ath9k,
brcmfmac, wil6210, and a handful of other bits here and there...

Please let me know if there are problems!
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Herbert Xu says:

====================
ipv4: Simplify raw_probe_proto_opt and avoid reading user iov twice

This series rewrites the function raw_probe_proto_opt in a more
readable fasion, and then fixes the long-standing bug where we
read the probed bytes twice which means that what we're using to
probe may in fact be invalid.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Ever since raw_probe_proto_opt was added it had the problem of
causing the user iov to be read twice, once during the probe for
the protocol header and once again in ip_append_data.

This is a potential security problem since it means that whatever
we're probing may be invalid.  This patch plugs the hole by
firstly advancing the iov so we don't read the same spot again,
and secondly saving what we read the first time around for use
by ip_append_data.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

The function raw_probe_proto_opt tries to extract the first two
bytes from the user input in order to seed the IPsec lookup for
ICMP packets.  In doing so it's processing iovec by hand and
overcomplicating things.

This patch replaces the manual iovec processing with a call to
memcpy_fromiovecend.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

This ways drivers like cxgb4 don't need to do ugly relative includes.
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Just use the address of the in6_addr.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Hariprasad Shenai says:

====================
RDMA/cxgb4,cxgb4vf,cxgb4i,csiostor: Cleanup macros

This series moves the debugfs code to a new file debugfs.c and cleans up
macros/register defines.

Various patches have ended up changing the style of the symbolic macros/register
defines and some of them used the macros/register defines that matches the
output of the script from the hardware team.

As a result, the current kernel.org files are a mix of different macro styles.
Since this macro/register defines is used by five different drivers, a
few patch series have ended up adding duplicate macro/register define entries
with different styles. This makes these register define/macro files a complete
mess and we want to make them clean and consistent.

Will post few more series so that we can cover all the macros so that they all
follow the same style to be consistent.

The patches series is created against 'net-next' tree.
And includes patches on cxgb4, cxgb4vf, iw_cxgb4, csiostor and cxgb4i driver.

We have included all the maintainers of respective drivers. Kindly review the
change and let us know in case of any review comments.

V3: Use suffix instead of prefix for macros/register defines
V2: Changes the description and cover-letter content to answer David Miller's
question
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Various patches have ended up changing the style of the symbolic macros/register
defines to different style.

As a result, the current kernel.org files are a mix of different macro styles.
Since this macro/register defines is used by different drivers a
few patch series have ended up adding duplicate macro/register define entries
with different styles. This makes these register define/macro files a complete
mess and we want to make them clean and consistent. This patch cleans up a part
of it.
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Various patches have ended up changing the style of the symbolic macros/register
to different style.

As a result, the current kernel.org files are a mix of different macro styles.
Since this macro/register defines is used by different drivers a
few patch series have ended up adding duplicate macro/register define entries
with different styles. This makes these register define/macro files a complete
mess and we want to make them clean and consistent. This patch cleans up a part
of it.
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

To enable gro_flush_timeout, a driver has to use napi_complete_done()
instead of napi_complete().

Tested:
 Ran 200 netperf TCP_STREAM from A to B (10Gbe mlx4 link, 8 RX queues)

Without this feature, we send back about 305,000 ACK per second.

GRO aggregation ratio is low (811/305 = 2.65 segments per GRO packet)

Setting a timer of 2000 nsec is enough to increase GRO packet sizes
and reduce number of ACK packets. (811/19.2 = 42)

Receiver performs less calls to upper stacks, less wakes up.
This also reduces cpu usage on the sender, as it receives less ACK
packets.

Note that reducing number of wakes up increases cpu efficiency, but can
decrease QPS, as applications wont have the chance to warmup cpu caches
doing a partial read of RPC requests/answers if they fit in one skb.

B:~# sar -n DEV 1 10 | grep eth0 | tail -1
Average:         eth0 811269.80 305732.30 1199462.57  19705.72      0.00
0.00      0.50

B:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout

B:~# sar -n DEV 1 10 | grep eth0 | tail -1
Average:         eth0 811577.30  19230.80 1199916.51   1239.80      0.00
0.00      0.50
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Tuning coalescing parameters on NIC can be really hard.

Servers can handle both bulk and RPC like traffic, with conflicting
goals : bulk flows want as big GRO packets as possible, RPC want minimal
latencies.

To reach big GRO packets on 10Gbe NIC, one can use :

ethtool -C eth0 rx-usecs 4 rx-frames 44

But this penalizes rpc sessions, with an increase of latencies, up to
50% in some cases, as NICs generally do not force an interrupt when
a packet with TCP Push flag is received.

Some NICs do not have an absolute timer, only a timer rearmed for every
incoming packet.

This patch uses a different strategy : Let GRO stack decides what do do,
based on traffic pattern.

Packets with Push flag wont be delayed.
Packets without Push flag might be held in GRO engine, if we keep
receiving data.

This new mechanism is off by default, and shall be enabled by setting
/sys/class/net/ethX/gro_flush_timeout to a value in nanosecond.

To fully enable this mechanism, drivers should use napi_complete_done()
instead of napi_complete().

Tested:
 Ran 200 netperf TCP_STREAM from A to B (10Gbe mlx4 link, 8 RX queues)

Without this feature, we send back about 305,000 ACK per second.

GRO aggregation ratio is low (811/305 = 2.65 segments per GRO packet)

Setting a timer of 2000 nsec is enough to increase GRO packet sizes
and reduce number of ACK packets. (811/19.2 = 42)

Receiver performs less calls to upper stacks, less wakes up.
This also reduces cpu usage on the sender, as it receives less ACK
packets.

Note that reducing number of wakes up increases cpu efficiency, but can
decrease QPS, as applications wont have the chance to warmup cpu caches
doing a partial read of RPC requests/answers if they fit in one skb.

B:~# sar -n DEV 1 10 | grep eth0 | tail -1
Average:         eth0 811269.80 305732.30 1199462.57  19705.72      0.00
0.00      0.50

B:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout

B:~# sar -n DEV 1 10 | grep eth0 | tail -1
Average:         eth0 811577.30  19230.80 1199916.51   1239.80      0.00
0.00      0.50
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Babel uses rt_proto 42. Add to userspace visible header file.
Signed-off-by: Dave Taht <dave.taht@bufferbloat.net>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove the dependency on the "warning" sysctl (net_msg_warn)
which is only used by the LIMIT_NETDEBUG macro.

Convert the LIMIT_NETDEBUG use in DCCP_WARN to the more
common net_warn_ratelimited mechanism.

This still ratelimits based on the net_ratelimit()
function, but removes the check for the sysctl.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

As NIC multicast filtering isn't perfect, and some platforms are
quite content to spew broadcasts, we should not trigger an event
for skb:kfree_skb when we do not have a match for such an incoming
datagram.  We do though want to avoid sweeping the matter under the
rug entirely, so increment a suitable statistic.

This incorporates feedback from David L. Stevens, Karl Neiss and Eric
Dumazet.

V3 - use bool per David Miller
Signed-off-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Olivier having laid the groundwork this patch transmits the
multicast flag to the device to save some bus traffic.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

The entries in the Kbuild files are incorrectly sorted.
Matters for aesthetics only.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch fixes the following sparse warnings. One is fixed by casting return
value to a return type of the function. The others by creating a specific
stmmac_platform.h which provides the bits related to the platform driver.

drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:59:29: warning: incorrect type in return expression (different address spaces)
drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:59:29:    expected void *
drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:59:29:    got void [noderef] <asn:2>*reg

drivers/net/ethernet/stmicro/stmmac/dwmac-meson.c:64:29: warning: symbol 'meson6_dwmac_data' was not declared. Should it be static?
drivers/net/ethernet/stmicro/stmmac/dwmac-sti.c:354:29: warning: symbol 'stih4xx_dwmac_data' was not declared. Should it be static?
drivers/net/ethernet/stmicro/stmmac/dwmac-sti.c:361:29: warning: symbol 'stid127_dwmac_data' was not declared. Should it be static?
drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c:133:29: warning: symbol 'sun7i_gmac_data' was not declared. Should it be static?
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

There is a kernel helper to dump buffers in a hexdecimal format. This patch
substitutes the open coded function by calling that helper.

The output is slightly changed:
 - no lead space
 - ASCII part will be printed along with the dump
 - offset is longer than 3 characters (now 8)
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Herbert Xu says:

====================
Replace skb_copy_datagram_const_iovec with iterator version

This patch series adds the helper skb_copy_datagram_iter, which
is meant to replace both skb_copy_datagram_iovec and its evil
twin skb_copy_datagram_const_iovec.

It then converts tun and macvtap over to the new helper and finally
removes skb_copy_datagram_const_iovec which is only used by tun
and macvtap.

The copy_to_iter return value issue pointed out by Al has now been
fixed.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Now that both macvtap and tun are using skb_copy_datagram_iter, we
can kill the abomination that is skb_copy_datagram_const_iovec.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch removes the use of skb_copy_datagram_const_iovec in
favour of the iovec iterator-based skb_copy_datagram_iter.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch removes the use of skb_copy_datagram_const_iovec in
favour of the iovec iterator-based skb_copy_datagram_iter.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch adds skb_copy_datagram_iter, which is identical to
skb_copy_datagram_iovec except that it operates on iov_iter
instead of iovec.

Eventually all users of skb_copy_datagram_iovec should switch
over to iov_iter and then we can remove skb_copy_datagram_iovec.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add definition to vxlan nla_policy for UDP checksum. This is necessary
to enable UDP checksums on VXLAN.

In some instances, enabling UDP checksums can improve performance on
receive for devices that return legacy checksum-unnecessary for UDP/IP.
Also, UDP checksum provides some protection against VNI corruption.

Testing:

Ran 200 instances of TCP_STREAM and TCP_RR on bnx2x.

TCP_STREAM
  IPv4, without UDP checksums
      14.41% TX CPU utilization
      25.71% RX CPU utilization
      9083.4 Mbps
  IPv4, with UDP checksums
      13.99% TX CPU utilization
      13.40% RX CPU utilization
      9095.65 Mbps

TCP_RR
  IPv4, without UDP checksums
      94.08% TX CPU utilization
      156/248/462 90/95/99% latencies
      1.12743e+06 tps
  IPv4, with UDP checksums
      94.43% TX CPU utilization
      158/250/462 90/95/99% latencies
      1.13345e+06 tps
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Tom Lendacky says:

====================
amd-xgbe: AMD XGBE driver updates 2014-11-06

The following series of patches fixes a couple of bugs that slipped
through my last series.

- Free channel structure after freeing the per channel interrupts
- If an skb error allocation occurs during receive processing check
  whether more descriptors are associated with the packet or whether
  to start on a new packet

This patch series is based on net-next.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

If the skb allocation fails during receive processing, the driver would
continue reading descriptors without first determining if there were
any more descriptors for the current packet. Update the code to check
whether more descriptors are associated with the current packet or
whether to move on to the next descriptor as a new packet.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The channel structure is freed before freeing the per channel
interrupts resulting in a kernel oops. Move the call to free
the channel structure to after the freeing of the per channel
interrupts.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

o Poll for the link events only if firmware doesn't have capability
  to notify the driver for the link events.
Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When we reuse the rx buffer, we need to update the desc. If not hardware sees
stale value.

In the following crash, when mtu is changed, hardware sees old rx buffer value
and crashes on skb_put.

Fix this by using enic_queue_rq_desc helper function which updates the necessary
desc.

[   64.657376] skbuff: skb_over_panic: text:ffffffffa041f55d len:9010 put:9010 head:ffff8800d3ca9fc0 data:ffff8800d3caa000 tail:0x2372 end:0x640 dev:enp0s3
[   64.659965] ------------[ cut here ]------------
[   64.661322] kernel BUG at net/core/skbuff.c:100!
[   64.662644] invalid opcode: 0000 [#1] PREEMPT SMP
[   64.664001] Modules linked in: rpcsec_gss_krb5 auth_rpcgss oid_registry nfsv4 cirrus ttm drm_kms_helper drm enic psmouse microcode evdev serio_raw syscopyarea sysfillrect sysimgblt i2c_piix4 i2c_core pcspkr nfs lockd grace sunrpc fscache ext4 crc16 mbcache jbd2 sd_mod ata_generic virtio_balloon ata_piix libata uhci_hcd virtio_pci virtio_ring usbcore usb_common virtio scsi_mod
[   64.664834] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W      3.17.0-netnext-10335-g942396b0-dirty #273
[   64.664834] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   64.664834] task: ffffffff81a1d580 ti: ffffffff81a00000 task.ti: ffffffff81a00000
[   64.664834] RIP: 0010:[<ffffffff81392cf1>]  [<ffffffff81392cf1>] skb_panic+0x61/0x70
[   64.664834] RSP: 0018:ffff880210603d48  EFLAGS: 00010292
[   64.664834] RAX: 000000000000008c RBX: ffff88020b0f6930 RCX: 0000000000000000
[   64.664834] RDX: 000000000000008c RSI: ffffffff8178b288 RDI: 00000000ffffffff
[   64.664834] RBP: ffff880210603d68 R08: 0000000000000001 R09: 0000000000000001
[   64.664834] R10: 00000000000005ce R11: 0000000000000001 R12: ffff88020b1f0b40
[   64.664834] R13: 000000000000a332 R14: ffff880209a1a000 R15: 0000000000000001
[   64.664834] FS:  0000000000000000(0000) GS:ffff880210600000(0000) knlGS:0000000000000000
[   64.664834] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[   64.664834] CR2: 00007f6752935e48 CR3: 0000000035743000 CR4: 00000000000006f0
[   64.664834] Stack:
[   64.664834]  ffff8800d3caa000 0000000000002372 0000000000000640 ffff88020b1f0000
[   64.664834]  ffff880210603d78 ffffffff81392d54 ffff880210603e08 ffffffffa041f55d
[   64.664834]  0000000000000296 ffffffff00000000 00008e7e00008e7e ffff880200002332
[   64.664834] Call Trace:
[   64.664834]  <IRQ>
[   64.664834]
[   64.664834]  [<ffffffff81392d54>] skb_put+0x54/0x60
[   64.664834]  [<ffffffffa041f55d>] enic_rq_service.constprop.47+0x3ad/0x730 [enic]
[   64.664834]  [<ffffffffa041fa79>] enic_poll_msix_rq+0x199/0x370 [enic]
[   64.664834]  [<ffffffff813a5499>] net_rx_action+0x139/0x210
[   64.664834]  [<ffffffff81290db3>] ? __this_cpu_preempt_check+0x13/0x20
[   64.664834]  [<ffffffff8106110e>] __do_softirq+0x14e/0x280
[   64.664834]  [<ffffffff8106152e>] irq_exit+0x8e/0xb0
[   64.664834]  [<ffffffff8100fd21>] do_IRQ+0x61/0x100
[   64.664834]  [<ffffffff814a2bf2>] common_interrupt+0x72/0x72

fixes: a03bb56e ("enic: implement rx_copybreak")
Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In case of error in rx path, we free the buf->os_buf but we do not make it NULL.
In next iteration we use the skb which is already freed. This causes the
following crash.

[  886.154772] general protection fault: 0000 [#1] PREEMPT SMP
[  886.154851] Modules linked in: rpcsec_gss_krb5 auth_rpcgss oid_registry nfsv4 microcode evdev cirrus ttm drm_kms_helper drm enic syscopyarea sysfillrect sysimgblt psmouse i2c_piix4 serio_raw pcspkr i2c_core nfs lockd grace sunrpc fscache ext4 crc16 mbcache jbd2 sd_mod crc_t10dif crct10dif_common ata_generic ata_piix virtio_balloon libata scsi_mod uhci_hcd usbcore virtio_pci virtio_ring virtio usb_common
[  886.155199] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W      3.17.0-netnext-05668-g876bc7f #272
[  886.155263] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  886.155304] task: ffffffff81a1d580 ti: ffffffff81a00000 task.ti: ffffffff81a00000
[  886.155356] RIP: 0010:[<ffffffff81384030>]  [<ffffffff81384030>] kfree_skb_list+0x10/0x30
[  886.155418] RSP: 0018:ffff880210603d48  EFLAGS: 00010206
[  886.155456] RAX: 0000000000000020 RBX: 0000000000000000 RCX: 0000000000000000
[  886.155504] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 004500084e000017
[  886.155553] RBP: ffff880210603d50 R08: 00000000fe13d1b6 R09: 0000000000000001
[  886.155601] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880209ff2f00
[  886.155650] R13: ffff88020ac0fe40 R14: ffff880209ff2f00 R15: ffff8800da8e3a80
[  886.155699] FS:  0000000000000000(0000) GS:ffff880210600000(0000) knlGS:0000000000000000
[  886.155774] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  886.155814] CR2: 00007f0e0c925000 CR3: 0000000035e8b000 CR4: 00000000000006f0
[  886.155865] Stack:
[  886.155882]  0000000000000000 ffff880210603d78 ffffffff81383f79 ffff880209ff2f00
[  886.155942]  ffff88020b0c0b40 000000000000c000 ffff880210603d90 ffffffff81383faf
[  886.156001]  ffff880209ff2f00 ffff880210603da8 ffffffff8138406d ffff88020b1b08c0
[  886.156061] Call Trace:
[  886.156080]  <IRQ>
[  886.156095]
[  886.156112]  [<ffffffff81383f79>] skb_release_data+0xa9/0xc0
[  886.157656]  [<ffffffff81383faf>] skb_release_all+0x1f/0x30
[  886.159195]  [<ffffffff8138406d>] consume_skb+0x1d/0x40
[  886.160719]  [<ffffffff813942e5>] __dev_kfree_skb_any+0x35/0x40
[  886.162224]  [<ffffffffa02dc1d5>] enic_rq_service.constprop.47+0xe5/0x5a0 [enic]
[  886.163756]  [<ffffffffa02dc829>] enic_poll_msix_rq+0x199/0x370 [enic]
[  886.164730]  [<ffffffff81397e29>] net_rx_action+0x139/0x210
[  886.164730]  [<ffffffff8105fb2e>] __do_softirq+0x14e/0x280
[  886.164730]  [<ffffffff8105ff2e>] irq_exit+0x8e/0xb0
[  886.164730]  [<ffffffff8100fc1d>] do_IRQ+0x5d/0x100
[  886.164730]  [<ffffffff81496832>] common_interrupt+0x72/0x72

fixes: a03bb56e ("enic: implement rx_copybreak")
Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>