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rxrpc: Fix error distribution

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Fix error distribution by immediately delivering the errors to all the
affected calls rather than deferring them to a worker thread.  The problem
with the latter is that retries and things can happen in the meantime when we
want to stop that sooner.

To this end:

 (1) Stop the error distributor from removing calls from the error_targets
     list so that peer->lock isn't needed to synchronise against other adds
     and removals.

 (2) Require the peer's error_targets list to be accessed with RCU, thereby
     avoiding the need to take peer->lock over distribution.

 (3) Don't attempt to affect a call's state if it is already marked complete.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
2018-09-27 15:13:09 +01:00
parent 37a675e768
commit f334430316
7 changed files with 16 additions and 64 deletions
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2
net/rxrpc/call_object.c
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@@ -400,7 +400,7 @@ void rxrpc_incoming_call(struct rxrpc_sock *rx,
rcu_assign_pointer(conn->channels[chan].call, call);
spin_lock(&conn->params.peer->lock);
hlist_add_head(&call->error_link, &conn->params.peer->error_targets);
hlist_add_head_rcu(&call->error_link, &conn->params.peer->error_targets);
spin_unlock(&conn->params.peer->lock);
_net("CALL incoming %d on CONN %d", call->debug_id, call->conn->debug_id);