Fix: multiple consumer locking problems

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

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 8c2bee33363614cbf58a4e5082aad84d9b8140ad..f5eb35c31e513e458a69c8d607c26764b916d577 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -123,6 +123,7 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 
                /* Poll on consumer socket. */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
+                       rcu_read_unlock();
                        return -EINTR;
                }
 
@@ -214,6 +215,7 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 
                /* block */
                if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
+                       rcu_read_unlock();
                        return -EINTR;
                }
 
@@ -221,6 +223,7 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
                if (ret != sizeof(fd)) {
                        lttng_consumer_send_error(ctx, CONSUMERD_ERROR_RECV_FD);
+                       rcu_read_unlock();
                        return ret;
                }
 
@@ -237,7 +240,7 @@ int lttng_kconsumer_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);
-                       goto end;
+                       goto end_nosignal;
                }
 
                /* The stream is not metadata. Get relayd reference if exists. */
@@ -250,13 +253,13 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                                        &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);
-                       goto end;
+                       goto end_nosignal;
                }
 
                if (ctx->on_recv_stream != NULL) {
@@ -264,7 +267,7 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                        if (ret == 0) {
                                consumer_add_stream(new_stream);
                        } else if (ret < 0) {
-                               goto end;
+                               goto end_nosignal;
                        }
                } else {
                        consumer_add_stream(new_stream);
@@ -275,30 +278,43 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
        }
        case LTTNG_CONSUMER_UPDATE_STREAM:
        {
-               if (ctx->on_update_stream != NULL) {
-                       ret = ctx->on_update_stream(msg.u.stream.stream_key, msg.u.stream.state);
-                       if (ret == 0) {
-                               consumer_change_stream_state(msg.u.stream.stream_key, msg.u.stream.state);
-                       } else if (ret < 0) {
-                               goto end;
-                       }
-               } else {
-                       consumer_change_stream_state(msg.u.stream.stream_key,
-                               msg.u.stream.state);
+               rcu_read_unlock();
+               return -ENOSYS;
+       }
+       case LTTNG_CONSUMER_DESTROY_RELAYD:
+       {
+               struct consumer_relayd_sock_pair *relayd;
+
+               DBG("Kernel consumer destroying relayd %zu",
+                               msg.u.destroy_relayd.net_seq_idx);
+
+               /* 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);
+                       goto end_nosignal;
                }
-               break;
+
+               /* Set destroy flag for this object */
+               uatomic_set(&relayd->destroy_flag, 1);
+
+               /* Destroy the relayd if refcount is 0 else set the destroy flag. */
+               if (uatomic_read(&relayd->refcount) == 0) {
+                       consumer_destroy_relayd(relayd);
+               }
+               goto end_nosignal;
        }
        default:
-               break;
+               goto end_nosignal;
        }
-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).