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<title>user/sven/linux.git/include/net/dst_ops.h, branch v3.17</title>
<subtitle>Linux Kernel
</subtitle>
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<updated>2012-07-19T17:43:03Z</updated>
<entry>
<title>net: Fix warnings in dst_ops.h</title>
<updated>2012-07-19T17:43:03Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2012-07-19T17:43:03Z</published>
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<id>urn:sha1:d8f1641b5829629d3af8e52750ba3b542f8f56c8</id>
<content type='text'>
include/net/dst_ops.h:28:20: warning: ‘struct sock’ declared inside parameter list

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Pass optional SKB and SK arguments to dst_ops-&gt;{update_pmtu,redirect}()</title>
<updated>2012-07-17T10:29:28Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2012-07-17T10:29:28Z</published>
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<id>urn:sha1:6700c2709c08d74ae2c3c29b84a30da012dbc7f1</id>
<content type='text'>
This will be used so that we can compose a full flow key.

Even though we have a route in this context, we need more.  In the
future the routes will be without destination address, source address,
etc. keying.  One ipv4 route will cover entire subnets, etc.

In this environment we have to have a way to possess persistent storage
for redirects and PMTU information.  This persistent storage will exist
in the FIB tables, and that's why we'll need to be able to rebuild a
full lookup flow key here.  Using that flow key will do a fib_lookup()
and create/update the persistent entry.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>ipv4: Generalize ip_do_redirect() and hook into new dst_ops-&gt;redirect.</title>
<updated>2012-07-12T03:55:47Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2012-07-12T03:55:47Z</published>
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<id>urn:sha1:e47a185b31dd2acd424fac7dc0efb96fc5b31a33</id>
<content type='text'>
All of the redirect acceptance policy is now contained within.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Add optional SKB arg to dst_ops-&gt;neigh_lookup().</title>
<updated>2012-07-05T08:04:01Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2012-07-03T04:52:24Z</published>
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<id>urn:sha1:f894cbf847c9bea1955095bf37aca6c050553167</id>
<content type='text'>
Causes the handler to use the daddr in the ipv4/ipv6 header when
the route gateway is unspecified (local subnet).

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: cleanup unsigned to unsigned int</title>
<updated>2012-04-15T16:44:40Z</updated>
<author>
<name>Eric Dumazet</name>
<email>eric.dumazet@gmail.com</email>
</author>
<published>2012-04-15T05:58:06Z</published>
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<id>urn:sha1:95c961747284a6b83a5e2d81240e214b0fa3464d</id>
<content type='text'>
Use of "unsigned int" is preferred to bare "unsigned" in net tree.

Signed-off-by: Eric Dumazet &lt;eric.dumazet@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Rename the dst_opt default_mtu method to mtu</title>
<updated>2011-11-26T19:29:50Z</updated>
<author>
<name>Steffen Klassert</name>
<email>steffen.klassert@secunet.com</email>
</author>
<published>2011-11-23T02:12:51Z</published>
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<id>urn:sha1:ebb762f27fed083cb993a0816393aba4615f6544</id>
<content type='text'>
We plan to invoke the dst_opt-&gt;default_mtu() method unconditioally
from dst_mtu(). So rename the method to dst_opt-&gt;mtu() to match
the name with the new meaning.

Signed-off-by: Steffen Klassert &lt;steffen.klassert@secunet.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Add -&gt;neigh_lookup() operation to dst_ops</title>
<updated>2011-07-18T07:40:17Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2011-07-18T07:40:17Z</published>
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<id>urn:sha1:d3aaeb38c40e5a6c08dd31a1b64da65c4352be36</id>
<content type='text'>
In the future dst entries will be neigh-less.  In that environment we
need to have an easy transition point for current users of
dst-&gt;neighbour outside of the packet output fast path.

Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Implement read-only protection and COW'ing of metrics.</title>
<updated>2011-01-27T04:51:05Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2011-01-27T04:51:05Z</published>
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<id>urn:sha1:62fa8a846d7de4b299232e330c74b7783539df76</id>
<content type='text'>
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: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Abstract default MTU metric calculation behind an accessor.</title>
<updated>2010-12-14T21:01:14Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2010-12-14T21:01:14Z</published>
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<id>urn:sha1:d33e455337ea2c71d09d7f4367d6ad6dd32b6965</id>
<content type='text'>
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: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>net: Abstract default ADVMSS behind an accessor.</title>
<updated>2010-12-13T20:52:14Z</updated>
<author>
<name>David S. Miller</name>
<email>davem@davemloft.net</email>
</author>
<published>2010-12-13T20:52:14Z</published>
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<id>urn:sha1:0dbaee3b37e118a96bb7b8eb0d9bbaeeb46264be</id>
<content type='text'>
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: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
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