Assert that the consumer lock is held while sending FDs to consumerd

The consumer_data lock must be held during the communications
between the consumerd and sessiond.

The consumer_data lock is refered-to by each consumer_socket
instance; they point to their consumer's global data lock.

The lock can't be taken in consumer_send_msg() or consumer_send_fds()
since we want to protect a complete "transaction". Some commands
require both functions to be called and we want to hold the lock
over the duration of both calls to protect against other
threads initiating a communication between the two calls.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/consumer.c b/src/bin/lttng-sessiond/consumer.c
index 8290b5faf05944fdae379a6b812f0a622020903e..826ec35667b1bc88a4acffcf34ed300fc52de2d9 100644 (file)
--- a/src/bin/lttng-sessiond/consumer.c
+++ b/src/bin/lttng-sessiond/consumer.c
@@ -739,6 +739,7 @@ int consumer_send_fds(struct consumer_socket *sock, int *fds, size_t nb_fd)
        assert(fds);
        assert(sock);
        assert(nb_fd > 0);
+       assert(pthread_mutex_trylock(sock->lock) == EBUSY);
 
        ret = lttcomm_send_fds_unix_sock(*sock->fd_ptr, fds, nb_fd);
        if (ret < 0) {