rxrpc: Call state should be read with READ_ONCE() under some circumstances
The call state may be changed at any time by the data-ready routine in
response to received packets, so if the call state is to be read and acted
upon several times in a function, READ_ONCE() must be used unless the call
state lock is held.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index bc2d3dc..47ccfea 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -488,6 +488,7 @@
int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
__releases(&rx->sk.sk_lock.slock)
{
+ enum rxrpc_call_state state;
enum rxrpc_command cmd;
struct rxrpc_call *call;
unsigned long user_call_ID = 0;
@@ -526,13 +527,17 @@
return PTR_ERR(call);
/* ... and we have the call lock. */
} else {
- ret = -EBUSY;
- if (call->state == RXRPC_CALL_UNINITIALISED ||
- call->state == RXRPC_CALL_CLIENT_AWAIT_CONN ||
- call->state == RXRPC_CALL_SERVER_PREALLOC ||
- call->state == RXRPC_CALL_SERVER_SECURING ||
- call->state == RXRPC_CALL_SERVER_ACCEPTING)
+ switch (READ_ONCE(call->state)) {
+ case RXRPC_CALL_UNINITIALISED:
+ case RXRPC_CALL_CLIENT_AWAIT_CONN:
+ case RXRPC_CALL_SERVER_PREALLOC:
+ case RXRPC_CALL_SERVER_SECURING:
+ case RXRPC_CALL_SERVER_ACCEPTING:
+ ret = -EBUSY;
goto error_release_sock;
+ default:
+ break;
+ }
ret = mutex_lock_interruptible(&call->user_mutex);
release_sock(&rx->sk);
@@ -542,10 +547,11 @@
}
}
+ state = READ_ONCE(call->state);
_debug("CALL %d USR %lx ST %d on CONN %p",
- call->debug_id, call->user_call_ID, call->state, call->conn);
+ call->debug_id, call->user_call_ID, state, call->conn);
- if (call->state >= RXRPC_CALL_COMPLETE) {
+ if (state >= RXRPC_CALL_COMPLETE) {
/* it's too late for this call */
ret = -ESHUTDOWN;
} else if (cmd == RXRPC_CMD_SEND_ABORT) {
@@ -555,12 +561,12 @@
} else if (cmd != RXRPC_CMD_SEND_DATA) {
ret = -EINVAL;
} else if (rxrpc_is_client_call(call) &&
- call->state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
+ state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
/* request phase complete for this client call */
ret = -EPROTO;
} else if (rxrpc_is_service_call(call) &&
- call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
- call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
+ state != RXRPC_CALL_SERVER_ACK_REQUEST &&
+ state != RXRPC_CALL_SERVER_SEND_REPLY) {
/* Reply phase not begun or not complete for service call. */
ret = -EPROTO;
} else {
@@ -605,14 +611,20 @@
_debug("CALL %d USR %lx ST %d on CONN %p",
call->debug_id, call->user_call_ID, call->state, call->conn);
- if (call->state >= RXRPC_CALL_COMPLETE) {
- ret = -ESHUTDOWN; /* it's too late for this call */
- } else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
- call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
- call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
- ret = -EPROTO; /* request phase complete for this client call */
- } else {
+ switch (READ_ONCE(call->state)) {
+ case RXRPC_CALL_CLIENT_SEND_REQUEST:
+ case RXRPC_CALL_SERVER_ACK_REQUEST:
+ case RXRPC_CALL_SERVER_SEND_REPLY:
ret = rxrpc_send_data(rxrpc_sk(sock->sk), call, msg, len);
+ break;
+ case RXRPC_CALL_COMPLETE:
+ /* It's too late for this call */
+ ret = -ESHUTDOWN;
+ break;
+ default:
+ /* Request phase complete for this client call */
+ ret = -EPROTO;
+ break;
}
mutex_unlock(&call->user_mutex);