linux-toradex.git/net/tipc/node.c, branch v3.14.3

tipc: rename functions related to link failover and improve comments

2014-01-07T23:44:25+00:00

The functionality related to link addition and failover is unnecessarily
hard to understand and maintain. We try to improve this by renaming
some of the functions, at the same time adding or improving the
explanatory comments around them. Names such as "tipc_rcv()" etc. also
align better with what is used in other networking components.

The changes in this commit are purely cosmetic, no functional changes
are made.

Signed-off-by: Jon Maloy 
Reviewed-by: Ying Xue 
Reviewed-by: Paul Gortmaker 
Signed-off-by: David S. Miller

tipc: remove unused code

2014-01-05T01:18:50+00:00

Remove dead code;
       tipc_bearer_find_interface
       tipc_node_redundant_links

This may break out of tree version of TIPC if there still is one.
But that maybe a good thing :-)

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

tipc: eliminate redundant code with kfree_skb_list routine

2013-12-11T05:17:42+00:00

sk_buff lists are currently relased by looping over the list and
explicitly releasing each buffer.

We replace all occurrences of this loop with a call to kfree_skb_list().

Signed-off-by: Ying Xue 
Reviewed-by: Paul Gortmaker 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: message reassembly using fragment chain

2013-11-07T23:30:11+00:00

When the first fragment of a long data data message is received on a link, a
reassembly buffer large enough to hold the data from this and all subsequent
fragments of the message is allocated. The payload of each new fragment is
copied into this buffer upon arrival. When the last fragment is received, the
reassembled message is delivered upwards to the port/socket layer.

Not only is this an inefficient approach, but it may also cause bursts of
reassembly failures in low memory situations. since we may fail to allocate
the necessary large buffer in the first place. Furthermore, after 100 subsequent
such failures the link will be reset, something that in reality aggravates the
situation.

To remedy this problem, this patch introduces a different approach. Instead of
allocating a big reassembly buffer, we now append the arriving fragments
to a reassembly chain on the link, and deliver the whole chain up to the
socket layer once the last fragment has been received. This is safe because
the retransmission layer of a TIPC link always delivers packets in strict
uninterrupted order, to the reassembly layer as to all other upper layers.
Hence there can never be more than one fragment chain pending reassembly at
any given time in a link, and we can trust (but still verify) that the
fragments will be chained up in the correct order.

Signed-off-by: Erik Hugne 
Reviewed-by: Paul Gortmaker 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

hlist: drop the node parameter from iterators

2013-02-28T03:10:24+00:00

I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin 
Acked-by: Paul E. McKenney 
Signed-off-by: Sasha Levin 
Cc: Wu Fengguang 
Cc: Marcelo Tosatti 
Cc: Gleb Natapov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

tipc: introduce message to synchronize broadcast link

2012-11-22T19:33:21+00:00

Upon establishing a first link between two nodes, there is
currently a risk that the two endpoints will disagree on exactly
which sequence number reception and acknowleding of broadcast
packets should start.

The following scenarios may happen:

1: Node A sends an ACTIVATE message to B, telling it to start acking
   packets from sequence number N.
2: Node A sends out broadcast N, but does not expect an acknowledge
   from B, since B is not yet in its broadcast receiver's list.
3: Node A receives ACK for N from all nodes except B, and releases
   packet N.
4: Node B receives the ACTIVATE, activates its link endpoint, and
   stores the value N as sequence number of first expected packet.
5: Node B sends a NAME_DISTR message to A.
6: Node A receives the NAME_DISTR message, and activates its endpoint.
   At this moment B is added to A's broadcast receiver's set.
   Node A also sets sequence number 0 as the first broadcast packet
   to be received from B.
7: Node A sends broadcast N+1.
8: B receives N+1, determines there is a gap in the sequence, since
   it is expecting N, and sends a NACK for N back to A.
9: Node A has already released N, so no retransmission is possible.
   The broadcast link in direction A->B is stale.

In addition to, or instead of, 7-9 above, the following may happen:

10: Node B sends broadcast M > 0 to A.
11: Node A receives M, falsely decides there must be a gap, since
    it is expecting packet 0, and asks for retransmission of packets
    [0,M-1].
12: Node B has already released these packets, so the broadcast
    link is stale in direction B->A.

We solve this problem by introducing a new unicast message type,
BCAST_PROTOCOL/STATE, to convey the sequence number of the next
sent broadcast packet to the other endpoint, at exactly the moment
that endpoint is added to the own node's broadcast receivers list,
and before any other unicast messages are permitted to be sent.

Furthermore, we don't allow any node to start receiving and
processing broadcast packets until this new synchronization
message has been received.

To maintain backwards compatibility, we still open up for
broadcast reception if we receive a NAME_DISTR message without
any preceding broadcast sync message. In this case, we must
assume that the other end has an older code version, and will
never send out the new synchronization message. Hence, for mixed
old and new nodes, the issue arising in 7-12 of the above may
happen with the same probability as before.

Signed-off-by: Jon Maloy 
Signed-off-by: Ying Xue 
Signed-off-by: Paul Gortmaker

tipc: rename supported flag to recv_permitted

2012-11-22T12:50:51+00:00

Rename the "supported" flag in bclink structure to "recv_permitted"
to better reflect what it is used for. When this flag is set for a
given node, we are permitted to receive and acknowledge broadcast
messages from that node.  Convert it to a bool at the same time,
since it is not used to store any numerical values.

Signed-off-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: Paul Gortmaker

tipc: remove supportable flag from bclink structure

2012-11-22T12:50:50+00:00

The "supportable" flag in bclink structure is a compatibility flag
indicating whether a peer node is capable of receiving TIPC broadcast
messages. However, all TIPC versions since tipc-1.5, and after the
inclusion in the upstream Linux kernel in 2006, support this capability.
It is highly unlikely that anybody is still using such an old
version of TIPC, let alone that they want to mix it with TIPC-2.0
nodes. Therefore, we now remove the "supportable" flag.

Signed-off-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: Paul Gortmaker

tipc: use standard printk shortcut macros (pr_err etc.)

2012-07-13T23:24:44+00:00

All messages should go directly to the kernel log.  The TIPC
specific error, warning, info and debug trace macro's are
removed and all references replaced with pr_err, pr_warn,
pr_info and pr_debug.

Commonly used sub-strings are explicitly declared as a const
char to reduce .text size.

Note that this means the debug messages (changed to pr_debug),
are now enabled through dynamic debugging, instead of a TIPC
specific Kconfig option (TIPC_DEBUG).  The latter will be
phased out completely

Signed-off-by: Erik Hugne 
Signed-off-by: Jon Maloy 
[PG: use pr_fmt as suggested by Joe Perches ]
Signed-off-by: Paul Gortmaker

tipc: compress out gratuitous extra carriage returns

2012-04-30T19:53:56+00:00

Some of the comment blocks are floating in limbo between two
functions, or between blocks of code.  Delete the extra line
feeds between any comment and its associated following block
of code, to be consistent with the majority of the rest of
the kernel.  Also delete trailing newlines at EOF and fix
a couple trivial typos in existing comments.

This is a 100% cosmetic change with no runtime impact.  We get
rid of over 500 lines of non-code, and being blank line deletes,
they won't even show up as noise in git blame.

Signed-off-by: Paul Gortmaker