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authorDavid Howells <dhowells@redhat.com>2016-06-27 16:39:44 +0300
committerDavid Howells <dhowells@redhat.com>2016-07-06 12:43:52 +0300
commita1399f8bb0331a1f50c76c4cac738fe57679b9bb (patch)
treed62082c1d288c38681962d90519005a4299c6c01 /net/rxrpc/conn_event.c
parent30b515f4d1cf31f6901c1fa61d920f651ebc07d7 (diff)
downloadlinux-a1399f8bb0331a1f50c76c4cac738fe57679b9bb.tar.xz
rxrpc: Call channels should have separate call number spaces
Each channel on a connection has a separate, independent number space from which to allocate callNumber values. It is entirely possible, for example, to have a connection with four active calls, each with call number 1. Note that the callNumber values for any particular channel don't have to start at 1, but they are supposed to increment monotonically for that channel from a client's perspective and may not be reused once the call number is transmitted (until the epoch cycles all the way back round). Currently, however, call numbers are allocated on a per-connection basis and, further, are held in an rb-tree. The rb-tree is redundant as the four channel pointers in the rxrpc_connection struct are entirely capable of pointing to all the calls currently in progress on a connection. To this end, make the following changes: (1) Handle call number allocation independently per channel. (2) Get rid of the conn->calls rb-tree. This is overkill as a connection may have a maximum of four calls in progress at any one time. Use the pointers in the channels[] array instead, indexed by the channel number from the packet. (3) For each channel, save the result of the last call that was in progress on that channel in conn->channels[] so that the final ACK or ABORT packet can be replayed if necessary. Any call earlier than that is just ignored. If we've seen the next call number in a packet, the last one is most definitely defunct. (4) When generating a RESPONSE packet for a connection, the call number counter for each channel must be included in it. (5) When parsing a RESPONSE packet for a connection, the call number counters contained therein should be used to set the minimum expected call numbers on each channel. To do in future commits: (1) Replay terminal packets based on the last call stored in conn->channels[]. (2) Connections should be retired before the callNumber space on any channel runs out. (3) A server is expected to disregard or reject any new incoming call that has a call number less than the current call number counter. The call number counter for that channel must be advanced to the new call number. Note that the server cannot just require that the next call that it sees on a channel be exactly the call number counter + 1 because then there's a scenario that could cause a problem: The client transmits a packet to initiate a connection, the network goes out, the server sends an ACK (which gets lost), the client sends an ABORT (which also gets lost); the network then reconnects, the client then reuses the call number for the next call (it doesn't know the server already saw the call number), but the server thinks it already has the first packet of this call (it doesn't know that the client doesn't know that it saw the call number the first time). Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc/conn_event.c')
-rw-r--r--net/rxrpc/conn_event.c24
1 files changed, 13 insertions, 11 deletions
diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
index f6ca8c5c4496..cee0f35bc1cf 100644
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -31,15 +31,17 @@ static void rxrpc_abort_calls(struct rxrpc_connection *conn, int state,
u32 abort_code)
{
struct rxrpc_call *call;
- struct rb_node *p;
+ int i;
_enter("{%d},%x", conn->debug_id, abort_code);
- read_lock_bh(&conn->lock);
+ spin_lock(&conn->channel_lock);
- for (p = rb_first(&conn->calls); p; p = rb_next(p)) {
- call = rb_entry(p, struct rxrpc_call, conn_node);
- write_lock(&call->state_lock);
+ for (i = 0; i < RXRPC_MAXCALLS; i++) {
+ call = rcu_dereference_protected(
+ conn->channels[i].call,
+ lockdep_is_held(&conn->channel_lock));
+ write_lock_bh(&call->state_lock);
if (call->state <= RXRPC_CALL_COMPLETE) {
call->state = state;
if (state == RXRPC_CALL_LOCALLY_ABORTED) {
@@ -51,10 +53,10 @@ static void rxrpc_abort_calls(struct rxrpc_connection *conn, int state,
}
rxrpc_queue_call(call);
}
- write_unlock(&call->state_lock);
+ write_unlock_bh(&call->state_lock);
}
- read_unlock_bh(&conn->lock);
+ spin_unlock(&conn->channel_lock);
_leave("");
}
@@ -192,7 +194,7 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
if (ret < 0)
return ret;
- read_lock_bh(&conn->lock);
+ spin_lock(&conn->channel_lock);
spin_lock(&conn->state_lock);
if (conn->state == RXRPC_CONN_SERVICE_CHALLENGING) {
@@ -200,12 +202,12 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
for (loop = 0; loop < RXRPC_MAXCALLS; loop++)
rxrpc_call_is_secure(
rcu_dereference_protected(
- conn->channels[loop],
- lockdep_is_held(&conn->lock)));
+ conn->channels[loop].call,
+ lockdep_is_held(&conn->channel_lock)));
}
spin_unlock(&conn->state_lock);
- read_unlock_bh(&conn->lock);
+ spin_unlock(&conn->channel_lock);
return 0;
default: