Allow drivers to use the new DSA API with platform data. Most of the
code in net/dsa/dsa2.c does not rely so much on device_nodes and can get
the same information from platform_data instead.

We purposely do not support distributed configurations with platform
data, so drivers should be providing a pointer to a 'struct
dsa_chip_data' structure if they wish to communicate per-port layout.

Multiple CPUs port could potentially be supported and dsa_chip_data is
extended to receive up to one reference to an upstream network device
per port described by a dsa_chip_data structure.

dsa_dev_to_net_device() increments the network device's reference count,
so we intentionally call dev_put() to be consistent with the DT-enabled
path, until we have a generic notifier based solution.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In preparation for using this function in net/dsa/dsa2.c, rename the function
to make its scope DSA specific, and export it.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The mv88e6390 ports 9 and 10 supports some additional PHY modes. Add
these modes to the PHY core so they can be used in the binding.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For XDP we will need to reset the queues to allow for buffer headroom
to be configured. In order to do this we need to essentially run the
freeze()/restore() code path. Unfortunately the locking requirements
between the freeze/restore and reset paths are different however so
we can not simply reuse the code.

This patch refactors the code path and adds a reset helper routine.
Signed-off-by: NJohn Fastabend <john.r.fastabend@intel.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A slave device will now notify the switch fabric once its port is
bridged or unbridged, instead of calling directly its switch operations.

This code allows propagating cross-chip bridging events in the fabric.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a notifier block per DSA switch, registered against a notifier head
in the switch fabric they belong to.

This infrastructure will allow to propagate fabric-wide events such as
port bridging, VLAN configuration, etc. If a DSA switch driver cares
about cross-chip configuration, such events can be caught.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch makes use of is_vlan_dev() function instead of flag
comparison which is exactly done by is_vlan_dev() helper function.
Signed-off-by: NParav Pandit <parav@mellanox.com>
Reviewed-by: NDaniel Jurgens <danielj@mellanox.com>
Acked-by: NStephen Hemminger <stephen@networkplumber.org>
Acked-by: NJon Maxwell <jmaxwell37@gmail.com>
Acked-by: NJohannes Thumshirn <jth@kernel.org>
Acked-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In commit 18bfb924 ("net: introduce default neigh_construct/destroy
ndo calls for L2 upper devices") we added these ndos to stacked devices
such as team and bond, so that calls will be propagated to mlxsw.

However, previous commit removed the reliance on these ndos and no new
users of these ndos have appeared since above mentioned commit. We can
therefore safely remove this dead code.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some CAN controllers don't implement a FIFO in hardware, but fill their
mailboxes in a particular order (from lowest to highest or highest to lowest).
This makes problems to read the frames in the correct order from the hardware,
as new frames might be filled into just read (low) mailboxes. This gets worse,
when following new frames are received into not read (higher) mailboxes.

On the bright side some these CAN controllers put a timestamp on each received
CAN frame. This patch adds support to offload CAN frames in interrupt context,
order them by timestamp and then transmitted in a NAPI context.
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Some CAN controllers have a usable FIFO already but can still benefit
from off-loading the CAN controller FIFO. The CAN frames of the FIFO are
read and put into a skb queue during interrupt and then transmitted in a
NAPI context.
Signed-off-by: NDavid Jander <david@protonic.nl>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

All __napi_complete() callers have been converted to
use the more standard napi_complete_done(),
we can now remove this NAPI method for good.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Change ip6_route_multipath_add to send one notifciation with the full
route encoded with RTA_MULTIPATH instead of a series of individual routes.
This is done by adding a skip_notify flag to the nl_info struct. The
flag is used to skip sending of the notification in the fib code that
actually inserts the route. Once the full route has been added, a
notification is generated with all nexthops.

ip6_route_multipath_add handles 3 use cases: new routes, route replace,
and route append. The multipath notification generated needs to be
consistent with the order of the nexthops and it should be consistent
with the order in a FIB dump which means the route with the first nexthop
needs to be used as the route reference. For the first 2 cases (new and
replace), a reference to the route used to send the notification is
obtained by saving the first route added. For the append case, the last
route added is used to loop back to its first sibling route which is
the first nexthop in the multipath route.
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IPv4 allows multipath routes to be deleted using just the prefix and
length. For example:
    $ ip ro ls vrf red
    unreachable default metric 8192
    1.1.1.0/24
        nexthop via 10.100.1.254  dev eth1 weight 1
        nexthop via 10.11.200.2  dev eth11.200 weight 1
    10.11.200.0/24 dev eth11.200 proto kernel scope link src 10.11.200.3
    10.100.1.0/24 dev eth1 proto kernel scope link src 10.100.1.3

    $ ip ro del 1.1.1.0/24 vrf red

    $ ip ro ls vrf red
    unreachable default metric 8192
    10.11.200.0/24 dev eth11.200 proto kernel scope link src 10.11.200.3
    10.100.1.0/24 dev eth1 proto kernel scope link src 10.100.1.3

The same notation does not work with IPv6 because of how multipath routes
are implemented for IPv6. For IPv6 only the first nexthop of a multipath
route is deleted if the request contains only a prefix and length. This
leads to unnecessary complexity in userspace dealing with IPv6 multipath
routes.

This patch allows all nexthops to be deleted without specifying each one
in the delete request. Internally, this is done by walking the sibling
list of the route matching the specifications given (prefix, length,
metric, protocol, etc).

    $  ip -6 ro ls vrf red
    2001:db8:1::/120 dev eth1 proto kernel metric 256  pref medium
    2001:db8:2::/120 dev eth2 proto kernel metric 256  pref medium
    2001:db8:200::/120 via 2001:db8:1::2 dev eth1 metric 1024  pref medium
    2001:db8:200::/120 via 2001:db8:2::2 dev eth2 metric 1024  pref medium
    ...

    $ ip -6 ro del vrf red 2001:db8:200::/120

    $ ip -6 ro ls vrf red
    2001:db8:1::/120 dev eth1 proto kernel metric 256  pref medium
    2001:db8:2::/120 dev eth2 proto kernel metric 256  pref medium
    ...

Because IPv6 allows individual nexthops to be deleted without deleting
the entire route, the ip6_route_multipath_del and non-multipath code
path (ip6_route_del) have to be discriminated so that all nexthops are
only deleted for the latter case. This is done by making the existing
fc_type in fib6_config a u16 and then adding a new u16 field with
fc_delete_all_nh as the first bit.
Suggested-by: NDinesh Dutt <ddutt@cumulusnetworks.com>
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We added generic support for busy polling in NAPI layer in linux-4.5

No network driver uses ndo_busy_poll() anymore, we can get rid
of the pointer in struct net_device_ops, and its use in sk_busy_loop()

Saves NETIF_F_BUSY_POLL features bit.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver that offloads flower rules needs to know with which priority
user inserted the rules. So add this information into offload struct.
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Acked-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This introduces a infrastructure for management of linear priority
areas. Priority order in an array matters, however order of items inside
a priority group does not matter.

As an initial implementation, L-sort algorithm is used. It is quite
trivial. More advanced algorithm called P-sort will be introduced as a
follow-up. The infrastructure is prepared for other algos.

Alongside this, a testing module is introduced as well.
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Similar to list_for_each_entry_continue and its reverse variant
list_for_each_entry_continue_reverse, introduce reverse helper for
list_for_each_entry_from.
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Acked-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Steven suggested to improve trace_print_hex_seq() a bit after commit
2acae0d5 ("trace: add variant without spacing in trace_print_hex_seq")
in two ways: i) by adding a kdoc comment for the helper function
itself and ii) by renaming 'spacing' argument into 'concatenate'
to better denote that we don't add spaces between each hex bytes.
Suggested-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

New nested netlink attribute to associate tunnel info per vlan.
This is used by bridge driver to send tunnel metadata to
bridge ports in vlan tunnel mode. This patch also adds new per
port flag IFLA_BRPORT_VLAN_TUNNEL to enable vlan tunnel mode.
off by default.

One example use for this is a vxlan bridging gateway or vtep
which maps vlans to vn-segments (or vnis). User can configure
per-vlan tunnel information which the bridge driver can use
to bridge vlan into the corresponding vn-segment.
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Vxlan COLLECT_METADATA mode today solves the per-vni netdev
scalability problem in l3 networks. It expects all forwarding
information to be present in dst_metadata. This patch series
enhances collect metadata mode to include the case where only
vni is present in dst_metadata, and the vxlan driver can then use
the rest of the forwarding information datbase to make forwarding
decisions. There is no change to default COLLECT_METADATA
behaviour. These changes only apply to COLLECT_METADATA when
used with the bridging use-case with a special dst_metadata
tunnel info flag (eg: where vxlan device is part of a bridge).
For all this to work, the vxlan driver will need to now support a
single fdb table hashed by mac + vni. This series essentially makes
this happen.

use-case and workflow:
vxlan collect metadata device participates in bridging vlan
to vn-segments. Bridge driver above the vxlan device,
sends the vni corresponding to the vlan in the dst_metadata.
vxlan driver will lookup forwarding database with (mac + vni)
for the required remote destination information to forward the
packet.

Changes introduced by this patch:
    - allow learning and forwarding database state in vxlan netdev in
      COLLECT_METADATA mode. Current behaviour is not changed
      by default. tunnel info flag IP_TUNNEL_INFO_BRIDGE is used
      to support the new bridge friendly mode.
    - A single fdb table hashed by (mac, vni) to allow fdb entries with
      multiple vnis in the same fdb table
    - rx path already has the vni
    - tx path expects a vni in the packet with dst_metadata
    - prior to this series, fdb remote_dsts carried remote vni and
      the vxlan device carrying the fdb table represented the
      source vni. With the vxlan device now representing multiple vnis,
      this patch adds a src vni attribute to the fdb entry. The remote
      vni already uses NDA_VNI attribute. This patch introduces
      NDA_SRC_VNI netlink attribute to represent the src vni in a multi
      vni fdb table.

iproute2 example (patched and pruned iproute2 output to just show
relevant fdb entries):
example shows same host mac learnt on two vni's.

before (netdev per vni):
$bridge fdb show | grep "00:02:00:00:00:03"
00:02:00:00:00:03 dev vxlan1001 dst 12.0.0.8 self
00:02:00:00:00:03 dev vxlan1000 dst 12.0.0.8 self

after this patch with collect metadata in bridged mode (single netdev):
$bridge fdb show | grep "00:02:00:00:00:03"
00:02:00:00:00:03 dev vxlan0 src_vni 1001 dst 12.0.0.8 self
00:02:00:00:00:03 dev vxlan0 src_vni 1000 dst 12.0.0.8 self
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

New ip_tunnel_info flag to represent bridged tunnel metadata.
Used by bridge driver later in the series to pass per vlan dst
metadata to bridge ports.
Signed-off-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the encode/decode functionality from the ife module instead of using
implementation inside the act_ife.
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NYotam Gigi <yotamg@mellanox.com>
Signed-off-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NRoman Mashak <mrv@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This module is responsible for the ife encapsulation protocol
encode/decode logics. That module can:
 - ife_encode: encode skb and reserve space for the ife meta header
 - ife_decode: decode skb and extract the meta header size
 - ife_tlv_meta_encode - encodes one tlv entry into the reserved ife
   header space.
 - ife_tlv_meta_decode - decodes one tlv entry from the packet
 - ife_tlv_meta_next - advance to the next tlv
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NYotam Gigi <yotamg@mellanox.com>
Signed-off-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NRoman Mashak <mrv@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As the function ife_tlv_meta_encode is not used by any other module,
unexport it and make it static for the act_ife module.
Signed-off-by: NYotam Gigi <yotamg@mellanox.com>
Signed-off-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NRoman Mashak <mrv@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Small cleanup factorizing code doing the TCP_MAXSEG clamping.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Debugging issues caused by pfmemalloc is often tedious.

Add a new SNMP counter to more easily diagnose these problems.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Josef Bacik <jbacik@fb.com>
Acked-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The 88e1545 PHYs are discrete Marvell PHYs, found in a quad package on
the zii-devel-b board. Add support for it to the Marvell PHY driver.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This ioctl opens a file to which a socket is bound and
returns a file descriptor. The caller has to have CAP_NET_ADMIN
in the socket network namespace.

Currently it is impossible to get a path and a mount point
for a socket file. socket_diag reports address, device ID and inode
number for unix sockets. An address can contain a relative path or
a file may be moved somewhere. And these properties say nothing about
a mount namespace and a mount point of a socket file.

With the introduced ioctl, we can get a path by reading
/proc/self/fd/X and get mnt_id from /proc/self/fdinfo/X.

In CRIU we are going to use this ioctl to dump and restore unix socket.

Here is an example how it can be used:

$ strace -e socket,bind,ioctl ./test /tmp/test_sock
socket(AF_UNIX, SOCK_STREAM, 0)         = 3
bind(3, {sa_family=AF_UNIX, sun_path="test_sock"}, 11) = 0
ioctl(3, SIOCUNIXFILE, 0)           = 4
^Z

$ ss -a | grep test_sock
u_str  LISTEN     0      1      test_sock 17798                 * 0

$ ls -l /proc/760/fd/{3,4}
lrwx------ 1 root root 64 Feb  1 09:41 3 -> 'socket:[17798]'
l--------- 1 root root 64 Feb  1 09:41 4 -> /tmp/test_sock

$ cat /proc/760/fdinfo/4
pos:	0
flags:	012000000
mnt_id:	40

$ cat /proc/self/mountinfo | grep "^40\s"
40 19 0:37 / /tmp rw shared:23 - tmpfs tmpfs rw
Signed-off-by: NAndrei Vagin <avagin@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The mv88e6390 Ethernet switch has internal PHYs. These PHYs don't have
an model ID in the ID2 register. So the MDIO driver in the switch
intercepts reads to this register, and returns the switch family ID.
Extend the Marvell PHY driver by including this ID, and treat the PHY
as a 88E1540.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 69b34fb9 ("netfilter: xt_LOG: add net namespace support for
xt_LOG") disabled logging packets using the LOG target from non-init
namespaces. The motivation was to prevent containers from flooding
kernel log of the host. The plan was to keep it that way until syslog
namespace implementation allows containers to log in a safe way.

However, the work on syslog namespace seems to have hit a dead end
somewhere in 2013 and there are users who want to use xt_LOG in all
network namespaces. This patch allows to do so by setting

  /proc/sys/net/netfilter/nf_log_all_netns

to a nonzero value. This sysctl is only accessible from init_net so that
one cannot switch the behaviour from inside a container.
Signed-off-by: NMichal Kubecek <mkubecek@suse.cz>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Currently, the ip_vs_dest cache frees ip_vs_dest objects when their
reference count becomes < 0.  Aside from not being semantically sound,
this is problematic for the new type refcount_t, which will be introduced
shortly in a separate patch. refcount_t is the new kernel type for
holding reference counts, and provides overflow protection and a
constrained interface relative to atomic_t (the type currently being
used for kernel reference counts).

Per Julian Anastasov: "The problem is that dest_trash currently holds
deleted dests (unlinked from RCU lists) with refcnt=0."  Changing
dest_trash to hold dest with refcnt=1 will allow us to free ip_vs_dest
structs when their refcnt=0, in ip_vs_dest_put_and_free().
Signed-off-by: NDavid Windsor <dwindsor@gmail.com>
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

After this change conntrack operations (lookup, creation, matching from
ruleset) only access one instead of two sk_buff cache lines.

This works for normal conntracks because those are allocated from a slab
that guarantees hw cacheline or 8byte alignment (whatever is larger)
so the 3 bits needed for ctinfo won't overlap with nf_conn addresses.

Template allocation now does manual address alignment (see previous change)
on arches that don't have sufficent kmalloc min alignment.

Some spots intentionally use skb->_nfct instead of skb_nfct() helpers,
this is to avoid undoing the skb_nfct() use when we remove untracked
conntrack object in the future.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

The next change will merge skb->nfct pointer and skb->nfctinfo
status bits into single skb->_nfct (unsigned long) area.

For this to work nf_conn addresses must always be aligned at least on
an 8 byte boundary since we will need the lower 3bits to store nfctinfo.

Conntrack templates are allocated via kmalloc.
kbuild test robot reported
BUILD_BUG_ON failed: NFCT_INFOMASK >= ARCH_KMALLOC_MINALIGN
on v1 of this patchset, so not all platforms meet this requirement.

Do manual alignment if needed,  the alignment offset is stored in the
nf_conn entry protocol area. This works because templates are not
handed off to L4 protocol trackers.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Add a helper to assign a nf_conn entry and the ctinfo bits to an sk_buff.
This avoids changing code in followup patch that merges skb->nfct and
skb->nfctinfo into skb->_nfct.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Followup patch renames skb->nfct and changes its type so add a helper to
avoid intrusive rename change later.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Next patch makes direct skb->nfct access illegal, reduce noise
in next patch by using accessors we already have.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

It is never accessed for reading and the only places that write to it
are the icmp(6) handlers, which also set skb->nfct (and skb->nfctinfo).

The conntrack core specifically checks for attached skb->nfct after
->error() invocation and returns early in this case.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Commit cdba756f ("net: move ndo_features_check() close to
ndo_start_xmit()") inadvertently moved the doc comment for
.ndo_fix_features instead of .ndo_features_check. Fix the comment
ordering.

Fixes: cdba756f ("net: move ndo_features_check() close to ndo_start_xmit()")
Signed-off-by: NDimitris Michailidis <dmichail@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Under some circumstances, an fscache object can become queued such that it
fscache_object_work_func() can be called once the object is in the
OBJECT_DEAD state.  This results in the kernel oopsing when it tries to
invoke the handler for the state (which is hard coded to 0x2).

The way this comes about is something like the following:

 (1) The object dispatcher is processing a work state for an object.  This
     is done in workqueue context.

 (2) An out-of-band event comes in that isn't masked, causing the object to
     be queued, say EV_KILL.

 (3) The object dispatcher finishes processing the current work state on
     that object and then sees there's another event to process, so,
     without returning to the workqueue core, it processes that event too.
     It then follows the chain of events that initiates until we reach
     OBJECT_DEAD without going through a wait state (such as
     WAIT_FOR_CLEARANCE).

     At this point, object->events may be 0, object->event_mask will be 0
     and oob_event_mask will be 0.

 (4) The object dispatcher returns to the workqueue processor, and in due
     course, this sees that the object's work item is still queued and
     invokes it again.

 (5) The current state is a work state (OBJECT_DEAD), so the dispatcher
     jumps to it - resulting in an OOPS.

When I'm seeing this, the work state in (1) appears to have been either
LOOK_UP_OBJECT or CREATE_OBJECT (object->oob_table is
fscache_osm_lookup_oob).

The window for (2) is very small:

 (A) object->event_mask is cleared whilst the event dispatch process is
     underway - though there's no memory barrier to force this to the top
     of the function.

     The window, therefore is from the time the object was selected by the
     workqueue processor and made requeueable to the time the mask was
     cleared.

 (B) fscache_raise_event() will only queue the object if it manages to set
     the event bit and the corresponding event_mask bit was set.

     The enqueuement is then deferred slightly whilst we get a ref on the
     object and get the per-CPU variable for workqueue congestion.  This
     slight deferral slightly increases the probability by allowing extra
     time for the workqueue to make the item requeueable.

Handle this by giving the dead state a processor function and checking the
for the dead state address rather than seeing if the processor function is
address 0x2.  The dead state processor function can then set a flag to
indicate that it's occurred and give a warning if it occurs more than once
per object.

If this race occurs, an oops similar to the following is seen (note the RIP
value):

BUG: unable to handle kernel NULL pointer dereference at 0000000000000002
IP: [<0000000000000002>] 0x1
PGD 0
Oops: 0010 [#1] SMP
Modules linked in: ...
CPU: 17 PID: 16077 Comm: kworker/u48:9 Not tainted 3.10.0-327.18.2.el7.x86_64 #1
Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 12/27/2015
Workqueue: fscache_object fscache_object_work_func [fscache]
task: ffff880302b63980 ti: ffff880717544000 task.ti: ffff880717544000
RIP: 0010:[<0000000000000002>]  [<0000000000000002>] 0x1
RSP: 0018:ffff880717547df8  EFLAGS: 00010202
RAX: ffffffffa0368640 RBX: ffff880edf7a4480 RCX: dead000000200200
RDX: 0000000000000002 RSI: 00000000ffffffff RDI: ffff880edf7a4480
RBP: ffff880717547e18 R08: 0000000000000000 R09: dfc40a25cb3a4510
R10: dfc40a25cb3a4510 R11: 0000000000000400 R12: 0000000000000000
R13: ffff880edf7a4510 R14: ffff8817f6153400 R15: 0000000000000600
FS:  0000000000000000(0000) GS:ffff88181f420000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000000194a000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
 ffffffffa0363695 ffff880edf7a4510 ffff88093f16f900 ffff8817faa4ec00
 ffff880717547e60 ffffffff8109d5db 00000000faa4ec18 0000000000000000
 ffff8817faa4ec18 ffff88093f16f930 ffff880302b63980 ffff88093f16f900
Call Trace:
 [<ffffffffa0363695>] ? fscache_object_work_func+0xa5/0x200 [fscache]
 [<ffffffff8109d5db>] process_one_work+0x17b/0x470
 [<ffffffff8109e4ac>] worker_thread+0x21c/0x400
 [<ffffffff8109e290>] ? rescuer_thread+0x400/0x400
 [<ffffffff810a5acf>] kthread+0xcf/0xe0
 [<ffffffff810a5a00>] ? kthread_create_on_node+0x140/0x140
 [<ffffffff816460d8>] ret_from_fork+0x58/0x90
 [<ffffffff810a5a00>] ? kthread_create_on_node+0x140/0x140
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NJeremy McNicoll <jeremymc@redhat.com>
Tested-by: NFrank Sorenson <sorenson@redhat.com>
Tested-by: NBenjamin Coddington <bcodding@redhat.com>
Reviewed-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

ip6_make_flowlabel() determines the flow label for IPv6 packets. It's
supposed to be passed a flow label, which it returns as is if non-0 and
in some other cases, otherwise it calculates a new value.

The problem is callers often pass a flowi6.flowlabel, which may also
contain traffic class bits. If the traffic class is non-0
ip6_make_flowlabel() mistakes the non-0 it gets as a flow label and
returns the whole thing. Thus it can return a 'flow label' longer than
20b and the low 20b of that is typically 0 resulting in packets with 0
label. Moreover, different packets of a flow may be labeled differently.
For a TCP flow with ECN non-payload and payload packets get different
labels as exemplified by this pair of consecutive packets:

(pure ACK)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 0001 1100 1110 0100 1001 = Flow Label: 0x1ce49
    Payload Length: 32
    Next Header: TCP (6)

(payload)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
    Payload Length: 688
    Next Header: TCP (6)

This patch allows ip6_make_flowlabel() to be passed more than just a
flow label and has it extract the part it really wants. This was simpler
than modifying the callers. With this patch packets like the above become

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 32
    Next Header: TCP (6)

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 688
    Next Header: TCP (6)
Signed-off-by: NDimitris Michailidis <dmichail@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>