mptcp: refactor token container

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Replace the radix tree with a hash table allocated
at boot time. The radix tree has some shortcoming:
a single lock is contented by all the mptcp operation,
the lookup currently use such lock, and traversing
all the items would require a lock, too.

With hash table instead we trade a little memory to
address all the above - a per bucket lock is used.

To hash the MPTCP sockets, we re-use the msk' sk_node
entry: the MPTCP sockets are never hashed by the stack.
Replace the existing hash proto callbacks with a dummy
implementation, annotating the above constraint.

Additionally refactor the token creation to code to:

- limit the number of consecutive attempts to a fixed
maximum. Hitting a hash bucket with a long chain is
considered a failed attempt

- accept() no longer can fail to token management.

- if token creation fails at connect() time, we do
fallback to TCP (before the connection was closed)

v1 -> v2:
 - fix "no newline at end of file" - Jakub

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

...

This commit is contained in:

Paolo Abeni 2020-06-26 19:30:00 +02:00 • committed by David S. Miller

parent d39dceca38

commit 2c5ebd001d

4 changed files with 236 additions and 113 deletions

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45

net/mptcp/protocol.c

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14

net/mptcp/protocol.h

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19

net/mptcp/subflow.c

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265

net/mptcp/token.c

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