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authorErik Hugne <erik.hugne@ericsson.com>2013-11-06 09:28:06 +0100
committerDavid S. Miller <davem@davemloft.net>2013-11-07 18:30:11 -0500
commit40ba3cdf542a469aaa9083fa041656e59b109b90 (patch)
treebd7e7af25968b0646155e67b58ab0b03ce3d484d /net/tipc/node.h
parent528f6f4bf372511ebf6004eed822de8f749b5930 (diff)
downloadop-kernel-dev-40ba3cdf542a469aaa9083fa041656e59b109b90.zip
op-kernel-dev-40ba3cdf542a469aaa9083fa041656e59b109b90.tar.gz
tipc: message reassembly using fragment chain
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 <erik.hugne@ericsson.com> Reviewed-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc/node.h')
-rw-r--r--net/tipc/node.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/tipc/node.h b/net/tipc/node.h
index 3c189b3..e5e96c0 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -74,7 +74,8 @@
* @deferred_size: number of OOS b'cast messages in deferred queue
* @deferred_head: oldest OOS b'cast message received from node
* @deferred_tail: newest OOS b'cast message received from node
- * @defragm: list of partially reassembled b'cast message fragments from node
+ * @reasm_head: broadcast reassembly queue head from node
+ * @reasm_tail: last broadcast fragment received from node
* @recv_permitted: true if node is allowed to receive b'cast messages
*/
struct tipc_node {
@@ -98,7 +99,8 @@ struct tipc_node {
u32 deferred_size;
struct sk_buff *deferred_head;
struct sk_buff *deferred_tail;
- struct sk_buff *defragm;
+ struct sk_buff *reasm_head;
+ struct sk_buff *reasm_tail;
bool recv_permitted;
} bclink;
};
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