cc3baecb21
-----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIVAwUAV3zeiPSw1s6N8H32AQI9Iw//RxwhAzb+ovNIizPqcFRt4BIS3Or6unov Bx9jtq+U1POWZWtlIHYZKDH8ndxMnC56NkEHmpIK3uEiqJ6BoQPpDdfN+hhREysV Hoa+JOkMgufPBanU/JyKY/4vsmlvLuoOdppN1OA/kx1KECux9xJWIrvFsCUQGeat nDsdWChHkZAm/GDPZiFvxEBVaxDe2dmnDMBFTst1RsrH2uICSqM4k5srmjc3NPAY bsTqZeQGTIK1V9MggwBHxHFMvvERlGDpcrpoMRjeTzMmCpCg5endJoSu3hdNjHUO o5Fi50dhLI5jo84DQiXL0wM4SLND0QQygl+QeU3zlJYtsQsF6WxPnIEGqlGr3+WV I4wjDc5lxECyQIjCsrCo5ZwJ47Kqmm/ZQ4uGd9JooAVhqhP7/2dhFH0zXywJZzKs zo+dWTF5Xvde+mlknm1RCTgkdx3msPH9EVkEoO4FOPOAg6lhIMQFFXLXZfGr9oX6 V99t+8t8YhDPTbL4AQnzh/aMHtbpM6be4TYiRRjT6iZLuvWOPW/zpp/1hmyeEkbU KZNDunC2tH030Fx5toGi3b2i8M5SJdyex9Udg/YsNexpWmyHMS49PoGk9ZnRRPA+ xn9+xIVsqTh+xbiyCOPJqlQMMK9ayF7isT2N8T19qoVJxurdE/tMBdtKrJ5uTJFT W0n8KV46a+4= =1ZSd -----END PGP SIGNATURE----- Merge tag 'rxrpc-rewrite-20160706' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs David Howells says: ==================== rxrpc: Improve conn/call lookup and fix call number generation [ver #3] I've fixed a couple of patch descriptions and excised the patch that duplicated the connections list for reconsideration at a later date. For reference, the excised patch is sitting on the rxrpc-experimental branch of my git tree, based on top of the rxrpc-rewrite branch. Diffing it against yesterday's tag shows no differences. Would you prefer the patch set to be emailed afresh instead of a git-pull request? David --- Here's the next part of the AF_RXRPC rewrite. The two main purposes of this set are to fix the call number handling and to make use of RCU when looking up the connection or call to pass a received packet to. Important changes in this set include: (1) Avoidance of placing stack data into SG lists in rxkad so that kernel stacks can become vmalloc'd (Herbert Xu). (2) Calls cease pinning the connection they used as soon as possible, which allows the connection to be discarded sooner and allows the call channel on that connection to be reused earlier. (3) Make each call channel on a connection have a separate and independent call number space rather than having a shared number space for the connection. Call numbers should increment monotonically per channel on the client, and the server should ignore a call with a lower call number for that channel than the latest it has seen. The RESPONSE packet sets the minimum values of each call ID counter on a connection. (4) Look up calls by indexing the channel array on a connection rather than by keeping calls in an rbtree on that connection. Also look up calls using the channel array rather than using a hashtable. The call hashtable can then be removed. (5) Call terminal statuses are cached in the channel array for the last call. It is assumed that if we the server have seen call N, then the client no longer cares about call N-1 on the same channel. This will allow retransmission of the terminal status in future without the need to keep the rxrpc_call struct around. (6) Peer lookups are moved out of common connection handling code and into service connection handling code as client connections (a) must point to a peer before they can be used and (b) are looked up by a machine-unique connection ID directly, so we only need to look up the peer first if we're going to deal with a service call. (7) The reference count on a connection is held elevated by 1 whilst it is alive (ie. idle unused connections have a refcount of 1). The reaper will attempt to change the refcount from 1->0 and skip if this cannot be done, whilst look ups only increment the refcount if it's non-zero. This makes the implementation of RCU lookups easier as we don't have to get a ref on the connection or a lock on the connection list to prevent a connection being reaped whilst we're contemplating queueing a packet that initiates a new service call upon it. If we need to get a connection, but there's a dead connection in the tree, we use rb_replace_node() to replace the dead one with a new one. (8) Use a seqlock to validate the walk over the service connection rbtree attached to a peer when it's being walked in RCU mode. (9) Make the incoming call/connection packet handling code use RCU mode and locks and make it only take a reference if the call/connection gets queued on a workqueue. The intention is that the next set will introduce the connection lifetime management and capacity limits to prevent clients from overloading the server. There are some fixes too: (1) Verifying that a packet coming in to a client connection came from the expected source. (2) Fix handling of connection failure in client call creation where we don't reinitialise the list linkage block and a second attempt to unlink the failed connection oopses and also we don't set the state correctly, which causes an assertion failure. (3) New service calls were being added to the socket's accept queue under the wrong lock. Changes: (V2) In rxrpc_find_service_conn_rcu() initialised the sequence number to 0. Fixed the RCU handling in conn_service.c by introducing and using rb_replace_node_rcu() as an RCU-safe alternative in rxrpc_publish_service_conn(). Modified and used rcu_dereference_raw() to avoid RCU sparse warnings in rxrpc_find_service_conn_rcu(). Added in some missing RCU dereference wrappers. It seems to be necessary to turn on CONFIG_PROVE_RCU_REPEATEDLY as well as CONFIG_SPARSE_RCU_POINTER to get the static __rcu annotation checking to happen. Fixed some other sparse warnings, including a missing ntohs() in jumbo packet processing. (V3) Fixed some commit descriptions. Excised the patch that duplicated the connection list to separate out the procfs list for reconsideration at a later date. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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