Fix: consumer: unbalanced RCU read-side lock on error

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

diff --git a/src/common/consumer/consumer-stream.c b/src/common/consumer/consumer-stream.c
index 1f0aad00b5b05a5fd37ce2646d5e56a24a95a421..8256eac1040ba452147f89c30b8533fc12ea3ea7 100644 (file)
--- a/src/common/consumer/consumer-stream.c
+++ b/src/common/consumer/consumer-stream.c
@@ -161,9 +161,40 @@ static ssize_t consumer_stream_consume_mmap(
        const unsigned long padding_size =
                        subbuffer->info.data.padded_subbuf_size -
                        subbuffer->info.data.subbuf_size;
-
-       return lttng_consumer_on_read_subbuffer_mmap(
+       const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_mmap(
                        stream, &subbuffer->buffer.buffer, padding_size);
+
+       if (stream->net_seq_idx == -1ULL) {
+               /*
+                * When writing on disk, check that only the subbuffer (no
+                * padding) was written to disk.
+                */
+               if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
+                       DBG("Failed to write the entire padded subbuffer on disk (written_bytes: %zd, padded subbuffer size %lu)",
+                                       written_bytes,
+                                       subbuffer->info.data.padded_subbuf_size);
+               }
+       } else {
+               /*
+                * When streaming over the network, check that the entire
+                * subbuffer including padding was successfully written.
+                */
+               if (written_bytes != subbuffer->info.data.subbuf_size) {
+                       DBG("Failed to write only the subbuffer over the network (written_bytes: %zd, subbuffer size %lu)",
+                                       written_bytes,
+                                       subbuffer->info.data.subbuf_size);
+               }
+       }
+
+       /*
+        * If `lttng_consumer_on_read_subbuffer_mmap()` returned an error, pass
+        * it along to the caller, else return zero.
+        */
+       if (written_bytes < 0) {
+               ERR("Error reading mmap subbuffer: %zd", written_bytes);
+       }
+
+       return written_bytes;
 }
 
 static ssize_t consumer_stream_consume_splice(
@@ -171,8 +202,24 @@ static ssize_t consumer_stream_consume_splice(
                struct lttng_consumer_stream *stream,
                const struct stream_subbuffer *subbuffer)
 {
-       return lttng_consumer_on_read_subbuffer_splice(ctx, stream,
-                       subbuffer->info.data.padded_subbuf_size, 0);
+       const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_splice(
+                       ctx, stream, subbuffer->info.data.padded_subbuf_size, 0);
+
+       if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
+               DBG("Failed to write the entire padded subbuffer (written_bytes: %zd, padded subbuffer size %lu)",
+                               written_bytes,
+                               subbuffer->info.data.padded_subbuf_size);
+       }
+
+       /*
+        * If `lttng_consumer_on_read_subbuffer_splice()` returned an error,
+        * pass it along to the caller, else return zero.
+        */
+       if (written_bytes < 0) {
+               ERR("Error reading splice subbuffer: %zd", written_bytes);
+       }
+
+       return written_bytes;
 }
 
 static int consumer_stream_send_index(
@@ -442,13 +489,14 @@ struct lttng_consumer_stream *consumer_stream_create(
                goto end;
        }
 
+       rcu_read_lock();
+
        if (trace_chunk && !lttng_trace_chunk_get(trace_chunk)) {
                ERR("Failed to acquire trace chunk reference during the creation of a stream");
                ret = -1;
                goto error;
        }
 
-       rcu_read_lock();
        stream->chan = channel;
        stream->key = stream_key;
        stream->trace_chunk = trace_chunk;