Fix: multiple consumer locking problems

[lttng-tools.git] / src / common / ust-consumer / ust-consumer.c

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index c92d59d027c0e28c3914094257df5b22d97e59de..486ca26342e57077f4eca2b33e18720932d26686 100644 (file)
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -108,7 +108,7 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                return -ENOENT;
        }
 
                return -ENOENT;
        }
 

-       /* relayd need RCU read-side lock */
+       /* relayd needs RCU read-side lock */

        rcu_read_lock();
 
        switch (msg.cmd_type) {
        rcu_read_lock();
 
        switch (msg.cmd_type) {


@@ -133,6 +133,7 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 
                /* Poll on consumer socket. */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 
                /* Poll on consumer socket. */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {

+                       rcu_read_unlock();

                        return -EINTR;
                }
 
                        return -EINTR;
                }
 


@@ -200,11 +201,13 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 
                /* block */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 
                /* block */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {

+                       rcu_read_unlock();

                        return -EINTR;
                }
                ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
                if (ret != sizeof(fds)) {
                        lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
                        return -EINTR;
                }
                ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
                if (ret != sizeof(fds)) {
                        lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);

+                       rcu_read_unlock();

                        return ret;
                }
 
                        return ret;
                }
 


@@ -241,11 +244,13 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 
                /* block */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
 
                /* block */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {

+                       rcu_read_unlock();

                        return -EINTR;
                }
                ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
                if (ret != sizeof(fds)) {
                        lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
                        return -EINTR;
                }
                ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
                if (ret != sizeof(fds)) {
                        lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);

+                       rcu_read_unlock();

                        return ret;
                }
 
                        return ret;
                }
 


@@ -267,7 +272,7 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                                msg.u.stream.metadata_flag);
                if (new_stream == NULL) {
                        lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);
                                msg.u.stream.metadata_flag);
                if (new_stream == NULL) {
                        lttng_consumer_send_error(ctx, CONSUMERD_OUTFD_ERROR);

-                       goto end;
+                       goto end_nosignal;

                }
 
                /* The stream is not metadata. Get relayd reference if exists. */
                }
 
                /* The stream is not metadata. Get relayd reference if exists. */


@@ -280,13 +285,13 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                                        &new_stream->relayd_stream_id);
                        pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
                        if (ret < 0) {
                                        &new_stream->relayd_stream_id);
                        pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
                        if (ret < 0) {

-                               goto end;
+                               goto end_nosignal;

                        }
                } else if (msg.u.stream.net_index != -1) {
                        ERR("Network sequence index %d unknown. Not adding stream.",
                                        msg.u.stream.net_index);
                        free(new_stream);
                        }
                } else if (msg.u.stream.net_index != -1) {
                        ERR("Network sequence index %d unknown. Not adding stream.",
                                        msg.u.stream.net_index);
                        free(new_stream);

-                       goto end;
+                       goto end_nosignal;

                }
 
                if (ctx->on_recv_stream != NULL) {
                }
 
                if (ctx->on_recv_stream != NULL) {


@@ -294,7 +299,7 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                        if (ret == 0) {
                                consumer_add_stream(new_stream);
                        } else if (ret < 0) {
                        if (ret == 0) {
                                consumer_add_stream(new_stream);
                        } else if (ret < 0) {

-                               goto end;
+                               goto end_nosignal;

                        }
                } else {
                        consumer_add_stream(new_stream);
                        }
                } else {
                        consumer_add_stream(new_stream);


@@ -315,8 +320,8 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                /* Get relayd reference if exists. */
                relayd = consumer_find_relayd(msg.u.destroy_relayd.net_seq_idx);
                if (relayd == NULL) {
                /* Get relayd reference if exists. */
                relayd = consumer_find_relayd(msg.u.destroy_relayd.net_seq_idx);
                if (relayd == NULL) {

-                       ERR("Unable to find relayd %zu",
-                                       msg.u.destroy_relayd.net_seq_idx);
+                       ERR("Unable to find relayd %zu", msg.u.destroy_relayd.net_seq_idx);
+                       goto end_nosignal;

                }
 
                /* Set destroy flag for this object */
                }
 
                /* Set destroy flag for this object */


@@ -326,10 +331,11 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                if (uatomic_read(&relayd->refcount) == 0) {
                        consumer_destroy_relayd(relayd);
                }
                if (uatomic_read(&relayd->refcount) == 0) {
                        consumer_destroy_relayd(relayd);
                }

-               break;
+               goto end_nosignal;

        }
        case LTTNG_CONSUMER_UPDATE_STREAM:
        {
        }
        case LTTNG_CONSUMER_UPDATE_STREAM:
        {

+               rcu_read_unlock();

                return -ENOSYS;
 #if 0
                if (ctx->on_update_stream != NULL) {
                return -ENOSYS;
 #if 0
                if (ctx->on_update_stream != NULL) {


@@ -343,20 +349,20 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                        consumer_change_stream_state(msg.u.stream.stream_key,
                                msg.u.stream.state);
                }
                        consumer_change_stream_state(msg.u.stream.stream_key,
                                msg.u.stream.state);
                }

-#endif

                break;
                break;

+#endif

        }
        default:
                break;
        }
        }
        default:
                break;
        }

-end:
+

        /*
        /*

-        * Wake-up the other end by writing a null byte in the pipe
-        * (non-blocking). Important note: Because writing into the
-        * pipe is non-blocking (and therefore we allow dropping wakeup
-        * data, as long as there is wakeup data present in the pipe
-        * buffer to wake up the other end), the other end should
-        * perform the following sequence for waiting:
+        * Wake-up the other end by writing a null byte in the pipe (non-blocking).
+        * Important note: Because writing into the pipe is non-blocking (and
+        * therefore we allow dropping wakeup data, as long as there is wakeup data
+        * present in the pipe buffer to wake up the other end), the other end
+        * should perform the following sequence for waiting:
+        *

         * 1) empty the pipe (reads).
         * 2) perform update operation.
         * 3) wait on the pipe (poll).
         * 1) empty the pipe (reads).
         * 2) perform update operation.
         * 3) wait on the pipe (poll).