Copyright ownership transfer

[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 5464822aaa58678377869a30d7c8bd9dbae1c6ba..b6440bc2aef018102e48dcac2fa20c53b33f86db 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
+ * Copyright (C) 2011 EfficiOS Inc.
  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
@@ -139,7 +139,7 @@ error:
 /*
  * Take a snapshot of all the stream of a channel
  * RCU read-side lock must be held across this function to ensure existence of
- * channel. The channel lock must be held by the caller.
+ * channel.
  *
  * Returns 0 on success, < 0 on error
  */
@@ -154,6 +154,9 @@ static int lttng_kconsumer_snapshot_channel(
 
        DBG("Kernel consumer snapshot channel %" PRIu64, key);
 
+       /* Prevent channel modifications while we perform the snapshot.*/
+       pthread_mutex_lock(&channel->lock);
+
        rcu_read_lock();
 
        /* Splice is not supported yet for channel snapshot. */
@@ -347,13 +350,14 @@ end_unlock:
        pthread_mutex_unlock(&stream->lock);
 end:
        rcu_read_unlock();
+       pthread_mutex_unlock(&channel->lock);
        return ret;
 }
 
 /*
  * Read the whole metadata available for a snapshot.
  * RCU read-side lock must be held across this function to ensure existence of
- * metadata_channel. The channel lock must be held by the caller.
+ * metadata_channel.
  *
  * Returns 0 on success, < 0 on error
  */
@@ -376,7 +380,7 @@ static int lttng_kconsumer_snapshot_metadata(
        metadata_stream = metadata_channel->metadata_stream;
        assert(metadata_stream);
 
-       pthread_mutex_lock(&metadata_stream->lock);
+       metadata_stream->read_subbuffer_ops.lock(metadata_stream);
        assert(metadata_channel->trace_chunk);
        assert(metadata_stream->trace_chunk);
 
@@ -431,7 +435,7 @@ static int lttng_kconsumer_snapshot_metadata(
 
        ret = 0;
 error_snapshot:
-       pthread_mutex_unlock(&metadata_stream->lock);
+       metadata_stream->read_subbuffer_ops.unlock(metadata_stream);
        cds_list_del(&metadata_stream->send_node);
        consumer_stream_destroy(metadata_stream, NULL);
        metadata_channel->metadata_stream = NULL;
@@ -961,7 +965,6 @@ error_streams_sent_nosignal:
                        ERR("Channel %" PRIu64 " not found", key);
                        ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
                } else {
-                       pthread_mutex_lock(&channel->lock);
                        if (msg.u.snapshot_channel.metadata == 1) {
                                int ret_snapshot;
 
@@ -989,7 +992,6 @@ error_streams_sent_nosignal:
                                        ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
                                }
                        }
-                       pthread_mutex_unlock(&channel->lock);
                }
                health_code_update();
 
@@ -1583,13 +1585,20 @@ end:
 }
 
 static
-int get_subbuffer_common(struct lttng_consumer_stream *stream,
+enum get_next_subbuffer_status get_subbuffer_common(
+               struct lttng_consumer_stream *stream,
                struct stream_subbuffer *subbuffer)
 {
        int ret;
+       enum get_next_subbuffer_status status;
 
        ret = kernctl_get_next_subbuf(stream->wait_fd);
-       if (ret) {
+       switch (ret) {
+       case 0:
+               status = GET_NEXT_SUBBUFFER_STATUS_OK;
+               break;
+       case -ENODATA:
+               case -EAGAIN:
                /*
                 * The caller only expects -ENODATA when there is no data to
                 * read, but the kernel tracer returns -EAGAIN when there is
@@ -1597,65 +1606,73 @@ int get_subbuffer_common(struct lttng_consumer_stream *stream,
                 * when there is no data for a finalized stream. Those can be
                 * combined into a -ENODATA return value.
                 */
-               if (ret == -EAGAIN) {
-                       ret = -ENODATA;
-               }
-
+               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
+               goto end;
+       default:
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
                goto end;
        }
 
        ret = stream->read_subbuffer_ops.extract_subbuffer_info(
-                       stream, subbuffer);
+               stream, subbuffer);
+       if (ret) {
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+       }
 end:
-       return ret;
+       return status;
 }
 
 static
-int get_next_subbuffer_splice(struct lttng_consumer_stream *stream,
+enum get_next_subbuffer_status get_next_subbuffer_splice(
+               struct lttng_consumer_stream *stream,
                struct stream_subbuffer *subbuffer)
 {
-       int ret;
+       const enum get_next_subbuffer_status status =
+                       get_subbuffer_common(stream, subbuffer);
 
-       ret = get_subbuffer_common(stream, subbuffer);
-       if (ret) {
+       if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
                goto end;
        }
 
        subbuffer->buffer.fd = stream->wait_fd;
 end:
-       return ret;
+       return status;
 }
 
 static
-int get_next_subbuffer_mmap(struct lttng_consumer_stream *stream,
+enum get_next_subbuffer_status get_next_subbuffer_mmap(
+               struct lttng_consumer_stream *stream,
                struct stream_subbuffer *subbuffer)
 {
        int ret;
+       enum get_next_subbuffer_status status;
        const char *addr;
 
-       ret = get_subbuffer_common(stream, subbuffer);
-       if (ret) {
+       status = get_subbuffer_common(stream, subbuffer);
+       if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
                goto end;
        }
 
        ret = get_current_subbuf_addr(stream, &addr);
        if (ret) {
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
                goto end;
        }
 
        subbuffer->buffer.buffer = lttng_buffer_view_init(
                        addr, 0, subbuffer->info.data.padded_subbuf_size);
 end:
-       return ret;
+       return status;
 }
 
 static
-int get_next_subbuffer_metadata_check(struct lttng_consumer_stream *stream,
+enum get_next_subbuffer_status get_next_subbuffer_metadata_check(struct lttng_consumer_stream *stream,
                struct stream_subbuffer *subbuffer)
 {
        int ret;
        const char *addr;
        bool coherent;
+       enum get_next_subbuffer_status status;
 
        ret = kernctl_get_next_subbuf_metadata_check(stream->wait_fd,
                        &coherent);
@@ -1688,11 +1705,27 @@ end:
         * for a non-finalized stream, and -ENODATA when there is no data for a
         * finalized stream. Those can be combined into a -ENODATA return value.
         */
-       if (ret == -EAGAIN) {
-               ret = -ENODATA;
+       switch (ret) {
+       case 0:
+               status = GET_NEXT_SUBBUFFER_STATUS_OK;
+               break;
+       case -ENODATA:
+       case -EAGAIN:
+               /*
+                * The caller only expects -ENODATA when there is no data to
+                * read, but the kernel tracer returns -EAGAIN when there is
+                * currently no data for a non-finalized stream, and -ENODATA
+                * when there is no data for a finalized stream. Those can be
+                * combined into a -ENODATA return value.
+                */
+               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
+               break;
+       default:
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               break;
        }
 
-       return ret;
+       return status;
 }
 
 static