rxrpc: Move client call connection to the I/O thread

Move the connection setup of client calls to the I/O thread so that a whole
load of locking and barrierage can be eliminated.  This necessitates the
app thread waiting for connection to complete before it can begin
encrypting data.

This also completes the fix for a race that exists between call connection
and call disconnection whereby the data transmission code adds the call to
the peer error distribution list after the call has been disconnected (say
by the rxrpc socket getting closed).

The fix is to complete the process of moving call connection, data
transmission and call disconnection into the I/O thread and thus forcibly
serialising them.

Note that the issue may predate the overhaul to an I/O thread model that
were included in the merge window for v6.2, but the timing is very much
changed by the change given below.

Fixes: cf37b5987508 ("rxrpc: Move DATA transmission into call processor work item")
Reported-by: syzbot+c22650d2844392afdcfd@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 64 insertions, 0 deletions

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index a5d0005b7ce5..da49fcf1c456 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -39,6 +39,60 @@ bool rxrpc_propose_abort(struct rxrpc_call *call, s32 abort_code, int error,
 }
 
 /*
+ * Wait for a call to become connected.  Interruption here doesn't cause the
+ * call to be aborted.
+ */
+static int rxrpc_wait_to_be_connected(struct rxrpc_call *call, long *timeo)
+{
+	DECLARE_WAITQUEUE(myself, current);
+	int ret = 0;
+
+	_enter("%d", call->debug_id);
+
+	if (rxrpc_call_state(call) != RXRPC_CALL_CLIENT_AWAIT_CONN)
+		return call->error;
+
+	add_wait_queue_exclusive(&call->waitq, &myself);
+
+	for (;;) {
+		ret = call->error;
+		if (ret < 0)
+			break;
+
+		switch (call->interruptibility) {
+		case RXRPC_INTERRUPTIBLE:
+		case RXRPC_PREINTERRUPTIBLE:
+			set_current_state(TASK_INTERRUPTIBLE);
+			break;
+		case RXRPC_UNINTERRUPTIBLE:
+		default:
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			break;
+		}
+		if (rxrpc_call_state(call) != RXRPC_CALL_CLIENT_AWAIT_CONN) {
+			ret = call->error;
+			break;
+		}
+		if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
+		     call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
+		    signal_pending(current)) {
+			ret = sock_intr_errno(*timeo);
+			break;
+		}
+		*timeo = schedule_timeout(*timeo);
+	}
+
+	remove_wait_queue(&call->waitq, &myself);
+	__set_current_state(TASK_RUNNING);
+
+	if (ret == 0 && rxrpc_call_is_complete(call))
+		ret = call->error;
+
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
  * Return true if there's sufficient Tx queue space.
  */
 static bool rxrpc_check_tx_space(struct rxrpc_call *call, rxrpc_seq_t *_tx_win)
@@ -239,6 +293,16 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 
 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 
+	ret = rxrpc_wait_to_be_connected(call, &timeo);
+	if (ret < 0)
+		return ret;
+
+	if (call->conn->state == RXRPC_CONN_CLIENT_UNSECURED) {
+		ret = rxrpc_init_client_conn_security(call->conn);
+		if (ret < 0)
+			return ret;
+	}
+
 	/* this should be in poll */
 	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);