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  1. 01 11月, 2019 23 次提交
  3. 31 10月, 2019 17 次提交
    • D
      Merge branch 'Control-action-percpu-counters-allocation-by-netlink-flag' · d86784fe
      由 David S. Miller 提交于 
      Vlad Buslov says:

====================
Control action percpu counters allocation by netlink flag

Currently, significant fraction of CPU time during TC filter allocation
is spent in percpu allocator. Moreover, percpu allocator is protected
with single global mutex which negates any potential to improve its
performance by means of recent developments in TC filter update API that
removed rtnl lock for some Qdiscs and classifiers. In order to
significantly improve filter update rate and reduce memory usage we
would like to allow users to skip percpu counters allocation for
specific action if they don't expect high traffic rate hitting the
action, which is a reasonable expectation for hardware-offloaded setup.
In that case any potential gains to software fast-path performance
gained by usage of percpu-allocated counters compared to regular integer
counters protected by spinlock are not important, but amount of
additional CPU and memory consumed by them is significant.

In order to allow configuring action counters allocation type at
runtime, implement following changes:

- Implement helper functions to update the action counters and use them
  in affected actions instead of updating counters directly. This steps
  abstracts actions implementation from counter types that are being
  used for particular action instance at runtime.

- Modify the new helpers to use percpu counters if they were allocated
  during action initialization and use regular counters otherwise.

- Extend action UAPI TCA_ACT space with TCA_ACT_FLAGS field. Add
  TCA_ACT_FLAGS_NO_PERCPU_STATS action flag and update
  hardware-offloaded actions to not allocate percpu counters when the
  flag is set.

With this changes users that prefer action update slow-path speed over
software fast-path speed can dynamically request actions to skip percpu
counters allocation without affecting other users.

Now, lets look at actual performance gains provided by this change.
Simple test is used to measure insertion rate - iproute2 TC is executed
in parallel by xargs in batch mode, its total execution time is measured
by shell builtin "time" command. The command runs 20 concurrent tc
instances, each with its own batch file with 100k rules:

$ time ls add* | xargs -n 1 -P 20 sudo tc -b

Two main rule profiles are tested. First is simple L2 flower classifier
with single gact drop action. The configuration is chosen as worst case
scenario because with single-action rules pressure on percpu allocator
is minimized. Example rule:

filter add dev ens1f0 protocol ip ingress prio 1 handle 1 flower skip_hw
    src_mac e4:11:0:0:0:0 dst_mac e4:12:0:0:0:0 action drop

Second profile is typical real-world scenario that uses flower
classifier with some L2-4 fields and two actions (tunnel_key+mirred).
Example rule:

filter add dev ens1f0_0 protocol ip ingress prio 1 handle 1 flower
    skip_hw src_mac e4:11:0:0:0:0 dst_mac e4:12:0:0:0:0 src_ip
    192.168.111.1 dst_ip 192.168.111.2 ip_proto udp dst_port 1 src_port
    1 action tunnel_key set id 1 src_ip 2.2.2.2 dst_ip 2.2.2.3 dst_port
    4789 action mirred egress redirect dev vxlan1

 Profile           |        percpu |     no_percpu | X improvement
                   | (k rules/sec) | (k rules/sec) |
-------------------+---------------+---------------+---------------
 Gact drop         |           203 |           259 |          1.28
 tunnel_key+mirred |            92 |           204 |          2.22

For simple drop action removing percpu allocation leads to ~25%
insertion rate improvement. Perf profiles highlights the bottlenecks.

Perf profile of run with percpu allocation (gact drop):

+ 89.11% 0.48% tc [kernel.vmlinux] [k] entry_SYSCALL_64
+ 88.58% 0.04% tc [kernel.vmlinux] [k] do_syscall_64
+ 87.50% 0.04% tc libc-2.29.so [.] __libc_sendmsg
+ 86.96% 0.04% tc [kernel.vmlinux] [k] __sys_sendmsg
+ 86.85% 0.01% tc [kernel.vmlinux] [k] ___sys_sendmsg
+ 86.60% 0.05% tc [kernel.vmlinux] [k] sock_sendmsg
+ 86.55% 0.12% tc [kernel.vmlinux] [k] netlink_sendmsg
+ 86.04% 0.13% tc [kernel.vmlinux] [k] netlink_unicast
+ 85.42% 0.03% tc [kernel.vmlinux] [k] netlink_rcv_skb
+ 84.68% 0.04% tc [kernel.vmlinux] [k] rtnetlink_rcv_msg
+ 84.56% 0.24% tc [kernel.vmlinux] [k] tc_new_tfilter
+ 75.73% 0.65% tc [cls_flower] [k] fl_change
+ 71.30% 0.03% tc [kernel.vmlinux] [k] tcf_exts_validate
+ 71.27% 0.13% tc [kernel.vmlinux] [k] tcf_action_init
+ 71.06% 0.01% tc [kernel.vmlinux] [k] tcf_action_init_1
+ 70.41% 0.04% tc [act_gact] [k] tcf_gact_init
+ 53.59% 1.21% tc [kernel.vmlinux] [k] __mutex_lock.isra.0
+ 52.34% 0.34% tc [kernel.vmlinux] [k] tcf_idr_create
- 51.23% 2.17% tc [kernel.vmlinux] [k] pcpu_alloc
  - 49.05% pcpu_alloc
    + 39.35% __mutex_lock.isra.0 4.99% memset_erms
    + 2.16% pcpu_alloc_area
  + 2.17% __libc_sendmsg
+ 45.89% 44.33% tc [kernel.vmlinux] [k] osq_lock
+ 9.94% 0.04% tc [kernel.vmlinux] [k] tcf_idr_check_alloc
+ 7.76% 0.00% tc [kernel.vmlinux] [k] tcf_idr_insert
+ 6.50% 0.03% tc [kernel.vmlinux] [k] tfilter_notify
+ 6.24% 6.11% tc [kernel.vmlinux] [k] mutex_spin_on_owner
+ 5.73% 5.32% tc [kernel.vmlinux] [k] memset_erms
+ 5.31% 0.18% tc [kernel.vmlinux] [k] tcf_fill_node

Here bottleneck is clearly in pcpu_alloc() function that takes more than
half CPU time, which is mostly wasted busy-waiting for internal percpu
allocator global lock.

With percpu allocation removed (gact drop):

+ 87.50% 0.51% tc [kernel.vmlinux] [k] entry_SYSCALL_64
+ 86.94% 0.07% tc [kernel.vmlinux] [k] do_syscall_64
+ 85.75% 0.04% tc libc-2.29.so [.] __libc_sendmsg
+ 85.00% 0.07% tc [kernel.vmlinux] [k] __sys_sendmsg
+ 84.84% 0.07% tc [kernel.vmlinux] [k] ___sys_sendmsg
+ 84.59% 0.01% tc [kernel.vmlinux] [k] sock_sendmsg
+ 84.58% 0.14% tc [kernel.vmlinux] [k] netlink_sendmsg
+ 83.95% 0.12% tc [kernel.vmlinux] [k] netlink_unicast
+ 83.34% 0.01% tc [kernel.vmlinux] [k] netlink_rcv_skb
+ 82.39% 0.12% tc [kernel.vmlinux] [k] rtnetlink_rcv_msg
+ 82.16% 0.25% tc [kernel.vmlinux] [k] tc_new_tfilter
+ 75.13% 0.84% tc [cls_flower] [k] fl_change
+ 69.92% 0.05% tc [kernel.vmlinux] [k] tcf_exts_validate
+ 69.87% 0.11% tc [kernel.vmlinux] [k] tcf_action_init
+ 69.61% 0.02% tc [kernel.vmlinux] [k] tcf_action_init_1
- 68.80% 0.10% tc [act_gact] [k] tcf_gact_init
  - 68.70% tcf_gact_init
    + 36.08% tcf_idr_check_alloc
    + 31.88% tcf_idr_insert
+ 63.72% 0.58% tc [kernel.vmlinux] [k] __mutex_lock.isra.0
+ 58.80% 56.68% tc [kernel.vmlinux] [k] osq_lock
+ 36.08% 0.04% tc [kernel.vmlinux] [k] tcf_idr_check_alloc
+ 31.88% 0.01% tc [kernel.vmlinux] [k] tcf_idr_insert

The gact actions (like all other actions types) are inserted in single
idr instance protected by global (per namespace) lock that becomes new
bottleneck with such simple rule profile and prevents achieving 2x+
performance increase that can be expected by looking at profiling data
for insertion action with percpu counter.

Perf profile of run with percpu allocation (tunnel_key+mirred):

+ 91.95% 0.21% tc [kernel.vmlinux] [k] entry_SYSCALL_64
+ 91.74% 0.06% tc [kernel.vmlinux] [k] do_syscall_64
+ 90.74% 0.01% tc libc-2.29.so [.] __libc_sendmsg
+ 90.52% 0.01% tc [kernel.vmlinux] [k] __sys_sendmsg
+ 90.50% 0.04% tc [kernel.vmlinux] [k] ___sys_sendmsg
+ 90.41% 0.02% tc [kernel.vmlinux] [k] sock_sendmsg
+ 90.38% 0.04% tc [kernel.vmlinux] [k] netlink_sendmsg
+ 90.10% 0.06% tc [kernel.vmlinux] [k] netlink_unicast
+ 89.76% 0.01% tc [kernel.vmlinux] [k] netlink_rcv_skb
+ 89.28% 0.04% tc [kernel.vmlinux] [k] rtnetlink_rcv_msg
+ 89.15% 0.03% tc [kernel.vmlinux] [k] tc_new_tfilter
+ 83.41% 0.33% tc [cls_flower] [k] fl_change
+ 81.17% 0.04% tc [kernel.vmlinux] [k] tcf_exts_validate
+ 81.13% 0.06% tc [kernel.vmlinux] [k] tcf_action_init
+ 81.04% 0.04% tc [kernel.vmlinux] [k] tcf_action_init_1
- 73.59% 2.16% tc [kernel.vmlinux] [k] pcpu_alloc
  - 71.42% pcpu_alloc
    + 61.41% __mutex_lock.isra.0 5.02% memset_erms
    + 2.93% pcpu_alloc_area
  + 2.16% __libc_sendmsg
+ 63.58% 0.17% tc [kernel.vmlinux] [k] tcf_idr_create
+ 63.40% 0.60% tc [kernel.vmlinux] [k] __mutex_lock.isra.0
+ 57.85% 56.38% tc [kernel.vmlinux] [k] osq_lock
+ 46.27% 0.13% tc [act_tunnel_key] [k] tunnel_key_init
+ 34.26% 0.02% tc [act_mirred] [k] tcf_mirred_init
+ 10.99% 0.00% tc [kernel.vmlinux] [k] dst_cache_init
+ 5.32% 5.11% tc [kernel.vmlinux] [k] memset_erms

With two times more actions pressure on percpu allocator doubles, so now
it takes ~74% of CPU execution time.

With percpu allocation removed (tunnel_key+mirred):

+ 86.02% 0.50% tc [kernel.vmlinux] [k] entry_SYSCALL_64
+ 85.51% 0.12% tc [kernel.vmlinux] [k] do_syscall_64
+ 84.40% 0.03% tc libc-2.29.so [.] __libc_sendmsg
+ 83.84% 0.03% tc [kernel.vmlinux] [k] __sys_sendmsg
+ 83.72% 0.01% tc [kernel.vmlinux] [k] ___sys_sendmsg
+ 83.56% 0.01% tc [kernel.vmlinux] [k] sock_sendmsg
+ 83.50% 0.08% tc [kernel.vmlinux] [k] netlink_sendmsg
+ 83.02% 0.17% tc [kernel.vmlinux] [k] netlink_unicast
+ 82.48% 0.00% tc [kernel.vmlinux] [k] netlink_rcv_skb
+ 81.89% 0.11% tc [kernel.vmlinux] [k] rtnetlink_rcv_msg
+ 81.71% 0.25% tc [kernel.vmlinux] [k] tc_new_tfilter
+ 73.99% 0.63% tc [cls_flower] [k] fl_change
+ 69.72% 0.00% tc [kernel.vmlinux] [k] tcf_exts_validate
+ 69.72% 0.09% tc [kernel.vmlinux] [k] tcf_action_init
+ 69.53% 0.05% tc [kernel.vmlinux] [k] tcf_action_init_1
+ 53.08% 0.91% tc [kernel.vmlinux] [k] __mutex_lock.isra.0
+ 45.52% 43.99% tc [kernel.vmlinux] [k] osq_lock
- 36.02% 0.21% tc [act_tunnel_key] [k] tunnel_key_init
  - 35.81% tunnel_key_init
    + 15.95% tcf_idr_check_alloc
    + 13.91% tcf_idr_insert
    - 4.70% dst_cache_init
      + 4.68% pcpu_alloc
+ 33.22% 0.04% tc [kernel.vmlinux] [k] tcf_idr_check_alloc
+ 32.34% 0.05% tc [act_mirred] [k] tcf_mirred_init
+ 28.24% 0.01% tc [kernel.vmlinux] [k] tcf_idr_insert
+ 7.79% 0.05% tc [kernel.vmlinux] [k] idr_alloc_u32
+ 7.67% 7.35% tc [kernel.vmlinux] [k] idr_get_free
+ 6.46% 6.22% tc [kernel.vmlinux] [k] mutex_spin_on_owner
+ 5.11% 0.05% tc [kernel.vmlinux] [k] tfilter_notify

With percpu allocation removed insertion rate is increased by ~120%.
Such rule profile scales much better than simple single action because
both types of actions were competing for single lock in percpu
allocator, but not for action idr lock, which is per-action. Note that
percpu allocator is still used by dst_cache in tunnel_key actions and
consumes 4.68% CPU time. Dst_cache seems like good opportunity for
further insertion rate optimization but is not addressed by this change.

Another improvement provided by this change is significantly reduced
memory usage. The test is implemented by sampling "used memory" value
from "vmstat -s" command output. Following table includes memory usage
measurements for same two configurations that were used for measuring
insertion rate:

 Profile           | Mem per rule | Mem per rule no_percpu | Less memory used
                   |         (KB) |                   (KB) |             (KB)
-------------------+--------------+------------------------+------------------
 Gact drop         |         3.91 |                   2.51 |              1.4
 tunnel_key+mirred |         6.73 |                   3.91 |              2.8

Results indicate that memory usage of percpu allocator per action is
~1.4 KB. Note that any measurements of percpu allocator memory usage is
inherently tied to particular setup since memory usage is linear to
number of cores in system. It is to be expected that on current top of
the line servers percpu allocator memory usage will be 2-5x more than on
24 CPUs setup that was used for testing.

Setup details: 2x Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz, 32GB memory

Patches applied on top of net-next branch:

commit 2203cbf2 (net-next) Author:
Russell King <rmk+kernel@armlinux.org.uk> Date: Tue Oct 15 11:38:39 2019
+0100

net: sfp: move fwnode parsing into sfp-bus layer

Changes V1 -> V2:

- Include memory measurements.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d86784fe
    • V
      tc-testing: implement tests for new fast_init action flag · 9ae6b787
      由 Vlad Buslov 提交于 
      Add basic tests to verify action creation with new fast_init flag for all
actions that support the flag.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9ae6b787
    • V
      net: sched: update action implementations to support flags · e3822678
      由 Vlad Buslov 提交于 
      Extend struct tc_action with new "tcfa_flags" field. Set the field in
tcf_idr_create() function and provide new helper
tcf_idr_create_from_flags() that derives 'cpustats' boolean from flags
value. Update individual hardware-offloaded actions init() to pass their
"flags" argument to new helper in order to skip percpu stats allocation
when user requested it through flags.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      e3822678
    • V
      net: sched: extend TCA_ACT space with TCA_ACT_FLAGS · abbb0d33
      由 Vlad Buslov 提交于 
      Extend TCA_ACT space with nla_bitfield32 flags. Add
TCA_ACT_FLAGS_NO_PERCPU_STATS as the only allowed flag. Parse the flags in
tcf_action_init_1() and pass resulting value as additional argument to
a_o->init().
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      abbb0d33
    • V
      net: sched: modify stats helper functions to support regular stats · 5e174d5e
      由 Vlad Buslov 提交于 
      Modify stats update helper functions introduced in previous patches in this
series to fallback to regular tc_action->tcfa_{b|q}stats if cpu stats are
not allocated for the action argument. If regular non-percpu allocated
counters are in use, then obtain action tcfa_lock while modifying them.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5e174d5e
    • V
      net: sched: don't expose action qstats to skb_tc_reinsert() · ef816f3c
      由 Vlad Buslov 提交于 
      Previous commit introduced helper function for updating qstats and
refactored set of actions to use the helpers, instead of modifying qstats
directly. However, one of the affected action exposes its qstats to
skb_tc_reinsert(), which then modifies it.

Refactor skb_tc_reinsert() to return integer error code and don't increment
overlimit qstats in case of error, and use the returned error code in
tcf_mirred_act() to manually increment the overlimit counter with new
helper function.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ef816f3c
    • V
      net: sched: extract qstats update code into functions · 26b537a8
      由 Vlad Buslov 提交于 
      Extract common code that increments cpu_qstats counters into standalone act
API functions. Change hardware offloaded actions that use percpu counter
allocation to use the new functions instead of accessing cpu_qstats
directly.

This commit doesn't change functionality.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      26b537a8
    • V
      net: sched: extract bstats update code into function · 5e1ad95b
      由 Vlad Buslov 提交于 
      Extract common code that increments cpu_bstats counter into standalone act
API function. Change hardware offloaded actions that use percpu counter
allocation to use the new function instead of incrementing cpu_bstats
directly.

This commit doesn't change functionality.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5e1ad95b
    • V
      net: sched: extract common action counters update code into function · c8ecebd0
      由 Vlad Buslov 提交于 
      Currently, all implementations of tc_action_ops->stats_update() callback
have almost exactly the same implementation of counters update
code (besides gact which also updates drop counter). In order to simplify
support for using both percpu-allocated and regular action counters
depending on run-time flag in following patches, extract action counters
update code into standalone function in act API.

This commit doesn't change functionality.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c8ecebd0
    • C
      net: qrtr: Simplify 'qrtr_tun_release()' · 21d8bd12
      由 Christophe JAILLET 提交于 
      Use 'skb_queue_purge()' instead of re-implementing it.
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      21d8bd12
    • D
      Merge branch '1GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue · dba7bf03
      由 David S. Miller 提交于 
      Jeff Kirsher says:

====================
1GbE Intel Wired LAN Driver Updates 2019-10-29

This series contains updates to e1000e, igb, ixgbe and i40e drivers.

Sasha adds support for Intel client platforms Comet Lake and Tiger Lake
to the e1000e driver.  Also adds a fix for a compiler warning that was
recently introduced, when CONFIG_PM_SLEEP is not defined, so wrap the
code that requires this kernel configuration to be defined.

Alex fixes a potential race condition between network configuration and
power management for e1000e, which is similar to a past issue in the igb
driver.  Also provided a bit of code cleanup since the driver no longer
checks for __E1000_DOWN.

Josh Hunt adds UDP segmentation offload support for igb, ixgbe and i40e.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      dba7bf03
    • Z
      wimax: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops · 84e93d99
      由 zhong jiang 提交于 
      It is more clear to use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs file
operation rather than DEFINE_SIMPLE_ATTRIBUTE.

It is detected with the help of coccinelle.
Signed-off-by: Nzhong jiang <zhongjiang@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      84e93d99
    • H
      net: dsa: add ethtool pause configuration support · a2a1a13b
      由 Heiner Kallweit 提交于 
      This patch adds glue logic to make pause settings per port
configurable vie ethtool.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a2a1a13b
    • G
      vxlan: drop "vxlan" parameter in vxlan_fdb_alloc() · 1d7a5526
      由 Guillaume Nault 提交于 
      This parameter has never been used.
Signed-off-by: NGuillaume Nault <gnault@redhat.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1d7a5526
    • H
      net: phy: marvell: add downshift support for 88E1145 · a319fb52
      由 Heiner Kallweit 提交于 
      Add downshift support for 88E1145, it uses the same downshift
configuration registers as 88E1111.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a319fb52
    • D
      Merge branch 'ICMP-flow-improvements' · 29f52875
      由 David S. Miller 提交于 
      Matteo Croce says:

====================
ICMP flow improvements

This series improves the flow inspector handling of ICMP packets:
The first two patches just add some comments in the code which would have saved
me a few minutes of time, and refactor a piece of code.
The third one adds to the flow inspector the capability to extract the
Identifier field, if present, so echo requests and replies are classified
as part of the same flow.
The fourth patch uses the function introduced earlier to the bonding driver,
so echo replies can be balanced across bonding slaves.

v1 -> v2:
 - remove unused struct members
 - add an helper to check for the Id field
 - use a local flow_dissector_key in the bonding to avoid
   changing behaviour of the flow dissector
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      29f52875
    • M
      bonding: balance ICMP echoes in layer3+4 mode · 58deb77c
      由 Matteo Croce 提交于 
      The bonding uses the L4 ports to balance flows between slaves. As the ICMP
protocol has no ports, those packets are sent all to the same device:

    # tcpdump -qltnni veth0 ip |sed 's/^/0: /' &
    # tcpdump -qltnni veth1 ip |sed 's/^/1: /' &
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 315, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 315, seq 1, length 64
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 316, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 316, seq 1, length 64
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 317, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 317, seq 1, length 64

But some ICMP packets have an Identifier field which is
used to match packets within sessions, let's use this value in the hash
function to balance these packets between bond slaves:

    # ping -qc1 192.168.0.2
    0: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 303, seq 1, length 64
    0: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 303, seq 1, length 64
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 304, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 304, seq 1, length 64

Aso, let's use a flow_dissector_key which defines FLOW_DISSECTOR_KEY_ICMP,
so we can balance pings encapsulated in a tunnel when using mode encap3+4:

    # ping -q 192.168.1.2 -c1
    0: IP 192.168.0.1 > 192.168.0.2: GREv0, length 102: IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 585, seq 1, length 64
    0: IP 192.168.0.2 > 192.168.0.1: GREv0, length 102: IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 585, seq 1, length 64
    # ping -q 192.168.1.2 -c1
    1: IP 192.168.0.1 > 192.168.0.2: GREv0, length 102: IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 586, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: GREv0, length 102: IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 586, seq 1, length 64
Signed-off-by: NMatteo Croce <mcroce@redhat.com>
Reviewed-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      58deb77c