Simplifies tail of __ip_route_output_key().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's a lot of redundancy and unnecessary stack frames
in the output route creation path.

1) Make __mkroute_output() return error pointers.

2) Eliminate ip_mkroute_output() entirely, made possible by #1.

3) Call __mkroute_output() directly and handling the returning error
   pointers in ip_route_output_slow().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Note that we do not generate the redirect netevent any longer,
because we don't create a new cached route.

Instead, once the new neighbour is bound to the cached route,
we emit a neigh update event instead.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The general idea is that if we learn new PMTU information, we
bump the peer genid.

This triggers the dst_ops->check() code to validate and if
necessary propagate the new PMTU value into the metrics.

Learned PMTU information self-expires.

This means that it is not necessary to kill a cached route
entry just because the PMTU information is too old.

As a consequence:

1) When the path appears unreachable (dst_ops->link_failure
   or dst_ops->negative_advice) we unwind the PMTU state if
   it is out of date, instead of killing the cached route.

   A redirected route will still be invalidated in these
   situations.

2) rt_check_expire(), rt_worker_func(), et al. are no longer
   necessary at all.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If we didn't have a routing cache, we would not be able to properly
propagate certain kinds of dynamic path attributes, for example
PMTU information and redirects.

The reason is that if we didn't have a routing cache, then there would
be no way to lookup all of the active cached routes hanging off of
sockets, tunnels, IPSEC bundles, etc.

Consider the case where we created a cached route, but no inetpeer
entry existed and also we were not asked to pre-COW the route metrics
and therefore did not force the creation a new inetpeer entry.

If we later get a PMTU message, or a redirect, and store this
information in a new inetpeer entry, there is no way to teach that
cached route about the newly existing inetpeer entry.

The facilities implemented here handle this problem.

First we create a generation ID.  When we create a cached route of any
kind, we remember the generation ID at the time of attachment.  Any
time we force-create an inetpeer entry in response to new path
information, we bump that generation ID.

The dst_ops->check() callback is where the knowledge of this event
is propagated.  If the global generation ID does not equal the one
stored in the cached route, and the cached route has not attached
to an inetpeer yet, we look it up and attach if one is found.  Now
that we've updated the cached route's information, we update the
route's generation ID too.

This clears the way for implementing PMTU and redirects directly in
the inetpeer cache.  There is absolutely no need to consult cached
route information in order to maintain this information.

At this point nothing bumps the inetpeer genids, that comes in the
later changes which handle PMTUs and redirects using inetpeers.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Nobody actually does anything in response to the event,
so just kill it off.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Like metrics, the ICMP rate limiting bits are cached state about
a destination.  So move it into the inet_peer entries.

If an inet_peer cannot be bound (the reason is memory allocation
failure or similar), the policy is to allow.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Always lookup to see if we have an existing inetpeer entry for
a route.  Let FLOWI_FLAG_PRECOW_METRICS merely influence the
"create" argument to rt_bind_peer().

Also, call rt_bind_peer() unconditionally since it is not
possible for rt->peer to be non-NULL at this point.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Both fib_trie and fib_hash have a local implementation of
fib_table_select_default().  This is completely unnecessary
code duplication.

Since we now remember the fib_table and the head of the fib
alias list of the default route, we can implement one single
generic version of this routine.

Looking at the fib_hash implementation you may get the impression
that it's possible for there to be multiple top-level routes in
the table for the default route.  The truth is, it isn't, the
insert code will only allow one entry to exist in the zero
prefix hash table, because all keys evaluate to zero and all
keys in a hash table must be unique.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When an IPSEC SA is still being set up, __xfrm_lookup() will return
-EREMOTE and so ip_route_output_flow() will return a blackhole route.
This can happen in a sndmsg call, and after d33e4553 ("net: Abstract
default MTU metric calculation behind an accessor.") this leads to a
crash in ip_append_data() because the blackhole dst_ops have no
default_mtu() method and so dst_mtu() calls a NULL pointer.

Fix this by adding default_mtu() methods (that simply return 0, matching
the old behavior) to the blackhole dst_ops.

The IPv4 part of this patch fixes a crash that I saw when using an IPSEC
VPN; the IPv6 part is untested because I don't have an IPv6 VPN, but it
looks to be needed as well.
Signed-off-by: NRoland Dreier <roland@purestorage.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The fib metric memory in this case is static in the kernel image,
so we don't need to reference count it since it's never going
to go away on us.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

TCP is going to record metrics for the connection,
so pre-COW the route metrics at route cache entry
creation time.

This avoids several atomic operations that have to
occur if we COW the metrics after the entry reaches
global visibility.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Please note that the IPSEC dst entry metrics keep using
the generic metrics COW'ing mechanism using kmalloc/kfree.

This gives the IPSEC routes an opportunity to use metrics
which are unique to their encapsulated paths.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Routing metrics are now copy-on-write.

Initially a route entry points it's metrics at a read-only location.
If a routing table entry exists, it will point there.  Else it will
point at the all zero metric place-holder called 'dst_default_metrics'.

The writeability state of the metrics is stored in the low bits of the
metrics pointer, we have two bits left to spare if we want to store
more states.

For the initial implementation, COW is implemented simply via kmalloc.
However future enhancements will change this to place the writable
metrics somewhere else, in order to increase sharing.  Very likely
this "somewhere else" will be the inetpeer cache.

Note also that this means that metrics updates may transiently fail
if we cannot COW the metrics successfully.

But even by itself, this patch should decrease memory usage and
increase cache locality especially for routing workloads.  In those
cases the read-only metric copies stay in place and never get written
to.

TCP workloads where metrics get updated, and those rare cases where
PMTU triggers occur, will take a very slight performance hit.  But
that hit will be alleviated when the long-term writable metrics
move to a more sharable location.

Since the metrics storage went from a u32 array of RTAX_MAX entries to
what is essentially a pointer, some retooling of the dst_entry layout
was necessary.

Most importantly, we need to preserve the alignment of the reference
count so that it doesn't share cache lines with the read-mostly state,
as per Eric Dumazet's alignment assertion checks.

The only non-trivial bit here is the move of the 'flags' member into
the writeable cacheline.  This is OK since we are always accessing the
flags around the same moment when we made a modification to the
reference count.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix dependencies of netfilter realm match: it depends on NET_CLS_ROUTE,
which itself depends on NET_SCHED; this dependency is missing from netfilter.

Since matching on realms is also useful without having NET_SCHED enabled and
the option really only controls whether the tclassid member is included in
route and dst entries, rename the config option to IP_ROUTE_CLASSID and move
it outside of traffic scheduling context to get rid of the NET_SCHED dependeny.
Reported-by: NVladis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

The preferred source address is currently ignored for local routes,
which results in all local connections having a src address that is the
same as the local dst address. Fix this by respecting the preferred source
address when it is provided for local routes.

This bug can be demonstrated as follows:

 # ifconfig dummy0 192.168.0.1
 # ip route show table local | grep local.*dummy0
 local 192.168.0.1 dev dummy0  proto kernel  scope host  src 192.168.0.1
 # ip route change table local local 192.168.0.1 dev dummy0 \
     proto kernel scope host src 127.0.0.1
 # ip route show table local | grep local.*dummy0
 local 192.168.0.1 dev dummy0  proto kernel  scope host  src 127.0.0.1

We now establish a local connection and verify the source IP
address selection:

 # nc -l 192.168.0.1 3128 &
 # nc 192.168.0.1 3128 &
 # netstat -ant | grep 192.168.0.1:3128.*EST
 tcp        0      0 192.168.0.1:3128        192.168.0.1:33228 ESTABLISHED
 tcp        0      0 192.168.0.1:33228       192.168.0.1:3128  ESTABLISHED
Signed-off-by: NJoel Sing <jsing@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In ip_route_output_slow(), instead of allowing a route to be created on
a not UPed device, report -ENETUNREACH immediately.

# ip tunnel add mode ipip remote 10.16.0.164 local
10.16.0.72 dev eth0
# (Note : tunl1 is down)
# ping -I tunl1 10.1.2.3
PING 10.1.2.3 (10.1.2.3) from 192.168.18.5 tunl1: 56(84) bytes of data.
(nothing)
# ./a.out tunl1
# ip tunnel del tunl1
Message from syslogd@shelby at Dec 22 10:12:08 ...
  kernel: unregister_netdevice: waiting for tunl1 to become free.
Usage count = 3

After patch:
# ping -I tunl1 10.1.2.3
connect: Network is unreachable
Reported-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: NOctavian Purdila <opurdila@ixiacom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Flush the routing cache only of entries that match the
network namespace in which the purge event occurred.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>

Like RTAX_ADVMSS, make the default calculation go through a dst_ops
method rather than caching the computation in the routing cache
entries.

Now dst metrics are pretty much left as-is when new entries are
created, thus optimizing metric sharing becomes a real possibility.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make all RTAX_ADVMSS metric accesses go through a new helper function,
dst_metric_advmss().

Leave the actual default metric as "zero" in the real metric slot,
and compute the actual default value dynamically via a new dst_ops
AF specific callback.

For stacked IPSEC routes, we use the advmss of the path which
preserves existing behavior.

Unlike ipv4/ipv6, DecNET ties the advmss to the mtu and thus updates
advmss on pmtu updates.  This inconsistency in advmss handling
results in more raw metric accesses than I wish we ended up with.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Always go through a new ip4_dst_hoplimit() helper, just like ipv6.

This allowed several simplifications:

1) The interim dst_metric_hoplimit() can go as it's no longer
   userd.

2) The sysctl_ip_default_ttl entry no longer needs to use
   ipv4_doint_and_flush, since the sysctl is not cached in
   routing cache metrics any longer.

3) ipv4_doint_and_flush no longer needs to be exported and
   therefore can be marked static.

When ipv4_doint_and_flush_strategy was removed some time ago,
the external declaration in ip.h was mistakenly left around
so kill that off too.

We have to move the sysctl_ip_default_ttl declaration into
ipv4's route cache definition header net/route.h, because
currently net/ip.h (where the declaration lives now) has
a back dependency on net/route.h
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use helper functions to hide all direct accesses, especially writes,
to dst_entry metrics values.

This will allow us to:

1) More easily change how the metrics are stored.

2) Implement COW for metrics.

In particular this will help us put metrics into the inetpeer
cache if that is what we end up doing.  We can make the _metrics
member a pointer instead of an array, initially have it point
at the read-only metrics in the FIB, and then on the first set
grab an inetpeer entry and point the _metrics member there.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>

And make an inet_getpeer_v4() helper, update callers.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the macros defined for the members of flowi to clean the code up.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When we test rt->fl.iif against zero, we're seeing if it's
an output or an input route.

Make that explicit with some helper functions.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It seems idev field in struct rtable has no special purpose, but adding
extra atomic ops.

We hold refcounts on the device itself (using percpu data, so pretty
cheap in current kernel).

infiniband case is solved using dst.dev instead of idev->dev

Removal of this field means routing without route cache is now using
shared data, percpu data, and only potential contention is a pair of
atomic ops on struct neighbour per forwarded packet.

About 5% speedup on routing test.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add __rcu annotations to :
        (struct dst_entry)->rt_next
        (struct rt_hash_bucket)->chain

And use appropriate rcu primitives to reduce sparse warnings if
CONFIG_SPARSE_RCU_POINTER=y
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There is no point using RCU for dst we allocate for a very short time
(used once).

Change dst_release() to take DST_NOCACHE into account, but also change
skb_dst_set_noref() to force a refcount increment for such dst.

This is a _huge_ gain, because we dont waste memory to store xx thousand
of dsts. Instead of queueing them to RCU, we can free them instantly.

CPU caches can stay hot, re-using same memory blocks to hold temporary
dsts.

Note : remove unneeded smp_mb__before_atomic_dec(); in dst_release(),
since atomic_dec_return() implies a full memory barrier.

Stress test, 160.000.000 udp frames sent, IP route cache disabled
(DDOS).

Before:

real    0m38.091s
user    0m13.189s
sys     7m53.018s

After:

real	0m29.946s
user	0m12.157s
sys	7m40.605s

For reference, if IP route cache was enabled :

real	0m32.030s
user	0m10.521s
sys	8m15.243s
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Change a few checks against the hardcoded broadcast address,
0xffffffff, to ipv4_is_lbcast().  Remove some existing checks
using ipv4_is_lbcast() that are now obviously superfluous.
Signed-off-by: NAndy Walls <awalls@md.metrocast.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

struct dst_ops tracks number of allocated dst in an atomic_t field,
subject to high cache line contention in stress workload.

Switch to a percpu_counter, to reduce number of time we need to dirty a
central location. Place it on a separate cache line to avoid dirtying
read only fields.

Stress test :

(Sending 160.000.000 UDP frames,
IP route cache disabled, dual E5540 @2.53GHz,
32bit kernel, FIB_TRIE, SLUB/NUMA)

Before:

real    0m51.179s
user    0m15.329s
sys     10m15.942s

After:

real	0m45.570s
user	0m15.525s
sys	9m56.669s

With a small reordering of struct neighbour fields, subject of a
following patch, (to separate refcnt from other read mostly fields)

real	0m41.841s
user	0m15.261s
sys	8m45.949s
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit "fib: RCU conversion of fib_lookup()" removed rcu_read_lock() from
__mkroute_output but left a couple of calls to rcu_read_unlock() in there.
This causes lockdep to complain that the rcu_read_unlock() call in
__ip_route_output_key causes a lock inbalance and quickly crashes the
kernel. The below fixes this for me.
Signed-off-by: NDimitris Michailidis <dm@chelsio.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

fib_lookup() converted to be called in RCU protected context, no
reference taken and released on a contended cache line (fib_clntref)

fib_table_lookup() and fib_semantic_match() get an additional parameter.

struct fib_info gets an rcu_head field, and is freed after an rcu grace
period.

Stress test :
(Sending 160.000.000 UDP frames on same neighbour,
IP route cache disabled, dual E5540 @2.53GHz,
32bit kernel, FIB_HASH) (about same results for FIB_TRIE)

Before patch :

real	1m31.199s
user	0m13.761s
sys	23m24.780s

After patch:

real	1m5.375s
user	0m14.997s
sys	15m50.115s

Before patch Profile :

13044.00 15.4% __ip_route_output_key vmlinux
 8438.00 10.0% dst_destroy           vmlinux
 5983.00  7.1% fib_semantic_match    vmlinux
 5410.00  6.4% fib_rules_lookup      vmlinux
 4803.00  5.7% neigh_lookup          vmlinux
 4420.00  5.2% _raw_spin_lock        vmlinux
 3883.00  4.6% rt_set_nexthop        vmlinux
 3261.00  3.9% _raw_read_lock        vmlinux
 2794.00  3.3% fib_table_lookup      vmlinux
 2374.00  2.8% neigh_resolve_output  vmlinux
 2153.00  2.5% dst_alloc             vmlinux
 1502.00  1.8% _raw_read_lock_bh     vmlinux
 1484.00  1.8% kmem_cache_alloc      vmlinux
 1407.00  1.7% eth_header            vmlinux
 1406.00  1.7% ipv4_dst_destroy      vmlinux
 1298.00  1.5% __copy_from_user_ll   vmlinux
 1174.00  1.4% dev_queue_xmit        vmlinux
 1000.00  1.2% ip_output             vmlinux

After patch Profile :

13712.00 15.8% dst_destroy             vmlinux
 8548.00  9.9% __ip_route_output_key   vmlinux
 7017.00  8.1% neigh_lookup            vmlinux
 4554.00  5.3% fib_semantic_match      vmlinux
 4067.00  4.7% _raw_read_lock          vmlinux
 3491.00  4.0% dst_alloc               vmlinux
 3186.00  3.7% neigh_resolve_output    vmlinux
 3103.00  3.6% fib_table_lookup        vmlinux
 2098.00  2.4% _raw_read_lock_bh       vmlinux
 2081.00  2.4% kmem_cache_alloc        vmlinux
 2013.00  2.3% _raw_spin_lock          vmlinux
 1763.00  2.0% __copy_from_user_ll     vmlinux
 1763.00  2.0% ip_output               vmlinux
 1761.00  2.0% ipv4_dst_destroy        vmlinux
 1631.00  1.9% eth_header              vmlinux
 1440.00  1.7% _raw_read_unlock_bh     vmlinux

Reference results, if IP route cache is enabled :

real	0m29.718s
user	0m10.845s
sys	7m37.341s

25213.00 29.5% __ip_route_output_key   vmlinux
 9011.00 10.5% dst_release             vmlinux
 4817.00  5.6% ip_push_pending_frames  vmlinux
 4232.00  5.0% ip_finish_output        vmlinux
 3940.00  4.6% udp_sendmsg             vmlinux
 3730.00  4.4% __copy_from_user_ll     vmlinux
 3716.00  4.4% ip_route_output_flow    vmlinux
 2451.00  2.9% __xfrm_lookup           vmlinux
 2221.00  2.6% ip_append_data          vmlinux
 1718.00  2.0% _raw_spin_lock_bh       vmlinux
 1655.00  1.9% __alloc_skb             vmlinux
 1572.00  1.8% sock_wfree              vmlinux
 1345.00  1.6% kfree                   vmlinux
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While doing stress tests with IP route cache disabled, and multi queue
devices, I noticed a very high contention on one rwlock used in
neighbour code.

When many cpus are trying to send frames (possibly using a high
performance multiqueue device) to the same neighbour, they fight for the
neigh->lock rwlock in order to call neigh_hh_init(), and fight on
hh->hh_refcnt (a pair of atomic_inc/atomic_dec_and_test())

But we dont need to call neigh_hh_init() for dst that are used only
once. It costs four atomic operations at least, on two contended cache
lines, plus the high contention on neigh->lock rwlock.

Introduce a new dst flag, DST_NOCACHE, that is set when dst was not
inserted in route cache.

With the stress test bench, sending 160000000 frames on one neighbour,
results are :

Before patch:

real	2m28.406s
user	0m11.781s
sys	36m17.964s


After patch:

real	1m26.532s
user	0m12.185s
sys	20m3.903s
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ip_route_output_slow() is enclosed in an rcu_read_lock() protected
section, so that no references are taken/released on device, thanks to
__ip_dev_find() & dev_get_by_index_rcu()

Tested with ip route cache disabled, and a stress test :

Before patch:

elapsed time :

real	1m38.347s
user	0m11.909s
sys	23m51.501s

Profile:

13788.00 22.7% ip_route_output_slow [kernel]
 7875.00 13.0% dst_destroy          [kernel]
 3925.00  6.5% fib_semantic_match   [kernel]
 3144.00  5.2% fib_rules_lookup     [kernel]
 3061.00  5.0% dst_alloc            [kernel]
 2276.00  3.7% rt_set_nexthop       [kernel]
 1762.00  2.9% fib_table_lookup     [kernel]
 1538.00  2.5% _raw_read_lock       [kernel]
 1358.00  2.2% ip_output            [kernel]

After patch:

real	1m28.808s
user	0m13.245s
sys	20m37.293s

10950.00 17.2% ip_route_output_slow [kernel]
10726.00 16.9% dst_destroy          [kernel]
 5170.00  8.1% fib_semantic_match   [kernel]
 3937.00  6.2% dst_alloc            [kernel]
 3635.00  5.7% rt_set_nexthop       [kernel]
 2900.00  4.6% fib_rules_lookup     [kernel]
 2240.00  3.5% fib_table_lookup     [kernel]
 1427.00  2.2% _raw_read_lock       [kernel]
 1157.00  1.8% kmem_cache_alloc     [kernel]
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While doing stress tests with a disabled IP route cache, I found
__mkroute_output() was touching three times in_device atomic refcount.

Use RCU to touch it once to reduce cache line ping pongs.

Before patch

time to perform the test
real	1m42.009s
user	0m12.545s
sys	25m0.726s

Profile :

16109.00 26.4% ip_route_output_slow   vmlinux
 7434.00 12.2% dst_destroy            vmlinux
 3280.00  5.4% fib_rules_lookup       vmlinux
 3252.00  5.3% fib_semantic_match     vmlinux
 2622.00  4.3% fib_table_lookup       vmlinux
 2535.00  4.1% dst_alloc              vmlinux
 1750.00  2.9% _raw_read_lock         vmlinux
 1532.00  2.5% rt_set_nexthop         vmlinux

After patch

real	1m36.503s
user	0m12.977s
sys	23m25.608s

14234.00 22.4% ip_route_output_slow   vmlinux
 8717.00 13.7% dst_destroy            vmlinux
 4052.00  6.4% fib_rules_lookup       vmlinux
 3951.00  6.2% fib_semantic_match     vmlinux
 3191.00  5.0% dst_alloc              vmlinux
 1764.00  2.8% fib_table_lookup       vmlinux
 1692.00  2.7% _raw_read_lock         vmlinux
 1605.00  2.5% rt_set_nexthop         vmlinux
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IPv4 and IPv6 have separate neighbour tables, so
the warning messages should be distinguishable.

[ Add a suitable message prefix on the ipv4 side as well -DaveM ]
Signed-off-by: NUlrich Weber <uweber@astaro.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

__in_dev_get_rtnl(dev_out) is called while RTNL is not held, thus
triggers a lockdep fault.

At this point, we only perform a raw test of dev_out->ip_ptr being NULL,
we dont need to make sure ip_ptr cant changed right after.

We can use rcu_dereference_raw() for this.
Reported-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

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

Blackhole routes are used when xfrm_lookup() returns -EREMOTE (error
triggered by IKE for example), hence this kind of route is always
temporary and so we should check if a better route exists for next
packets.
Bug has been introduced by commit d11a4dc1.
Signed-off-by: NJianzhao Wang <jianzhao.wang@6wind.com>
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>