rcu_read_lock();
+ /*
+ * Don't try to enable a channel if the session has been started at
+ * some point in time before. The tracer does not allow it.
+ */
+ if (session->has_been_started) {
+ ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+ goto error;
+ }
+
+ /*
+ * The ringbuffer (both in user space and kernel) behave badly in overwrite
+ * mode and with less than 2 subbuf so block it right away and send back an
+ * invalid attribute error.
+ */
+ if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
+ ret = LTTNG_ERR_INVALID;
+ goto error;
+ }
+
switch (domain->type) {
case LTTNG_DOMAIN_KERNEL:
{
kchan = trace_kernel_get_channel_by_name(attr->name,
session->kernel_session);
if (kchan == NULL) {
- /*
- * Don't try to create a channel if the session
- * has been started at some point in time
- * before. The tracer does not allow it.
- */
- if (session->started) {
- ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
- goto error;
- }
ret = channel_kernel_create(session->kernel_session, attr, wpipe);
if (attr->name[0] != '\0') {
session->kernel_session->has_non_default_channel = 1;
uchan = trace_ust_find_channel_by_name(chan_ht, attr->name);
if (uchan == NULL) {
- /*
- * Don't try to create a channel if the session
- * has been started at some point in time
- * before. The tracer does not allow it.
- */
- if (session->started) {
- ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
- goto error;
- }
ret = channel_ust_create(usess, attr, domain->buf_type);
if (attr->name[0] != '\0') {
usess->has_non_default_channel = 1;
int cmd_start_trace(struct ltt_session *session)
{
int ret;
+ unsigned long nb_chan = 0;
struct ltt_kernel_session *ksession;
struct ltt_ust_session *usess;
ksession = session->kernel_session;
usess = session->ust_session;
- if (session->enabled) {
- /* Already started. */
+ /* Is the session already started? */
+ if (session->active) {
ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
goto error;
}
- session->enabled = 1;
+ /*
+ * Starting a session without channel is useless since after that it's not
+ * possible to enable channel thus inform the client.
+ */
+ if (usess && usess->domain_global.channels) {
+ nb_chan += lttng_ht_get_count(usess->domain_global.channels);
+ }
+ if (ksession) {
+ nb_chan += ksession->channel_count;
+ }
+ if (!nb_chan) {
+ ret = LTTNG_ERR_NO_CHANNEL;
+ goto error;
+ }
/* Kernel tracing */
if (ksession != NULL) {
}
}
- session->started = 1;
+ /* Flag this after a successful start. */
+ session->has_been_started = 1;
+ session->active = 1;
ret = LTTNG_OK;
ksession = session->kernel_session;
usess = session->ust_session;
- if (!session->enabled) {
+ /* Session is not active. Skip everythong and inform the client. */
+ if (!session->active) {
ret = LTTNG_ERR_TRACE_ALREADY_STOPPED;
goto error;
}
- session->enabled = 0;
-
/* Kernel tracer */
if (ksession && ksession->started) {
DBG("Stop kernel tracing");
}
}
+ /* Flag inactive after a successful stop. */
+ session->active = 0;
ret = LTTNG_OK;
error:
assert(uris);
assert(nb_uri > 0);
- /* Can't enable consumer after session started. */
- if (session->enabled) {
+ /* Can't set consumer URI if the session is active. */
+ if (session->active) {
ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
goto error;
}
}
}
+ /*
+ * Make sure to set the session in output mode after we set URI since a
+ * session can be created without URL (thus flagged in no output mode).
+ */
+ session->output_traces = 1;
+ if (ksess) {
+ ksess->output_traces = 1;
+ } else if (usess) {
+ usess->output_traces = 1;
+ }
+
/* All good! */
ret = LTTNG_OK;
{
struct lttng_kernel_calibrate kcalibrate;
- kcalibrate.type = calibrate->type;
+ switch (calibrate->type) {
+ case LTTNG_CALIBRATE_FUNCTION:
+ default:
+ /* Default and only possible calibrate option. */
+ kcalibrate.type = LTTNG_KERNEL_CALIBRATE_KRETPROBE;
+ break;
+ }
+
ret = kernel_calibrate(kernel_tracer_fd, &kcalibrate);
if (ret < 0) {
ret = LTTNG_ERR_KERN_ENABLE_FAIL;
{
struct lttng_ust_calibrate ucalibrate;
- ucalibrate.type = calibrate->type;
+ switch (calibrate->type) {
+ case LTTNG_CALIBRATE_FUNCTION:
+ default:
+ /* Default and only possible calibrate option. */
+ ucalibrate.type = LTTNG_UST_CALIBRATE_TRACEPOINT;
+ break;
+ }
+
ret = ust_app_calibrate_glb(&ucalibrate);
if (ret < 0) {
ret = LTTNG_ERR_UST_CALIBRATE_FAIL;
strncpy(sessions[i].name, session->name, NAME_MAX);
sessions[i].name[NAME_MAX - 1] = '\0';
- sessions[i].enabled = session->enabled;
+ sessions[i].enabled = session->active;
sessions[i].snapshot_mode = session->snapshot_mode;
i++;
}
assert(session);
/* Session MUST be stopped to ask for data availability. */
- if (session->enabled) {
+ if (session->active) {
ret = LTTNG_ERR_SESSION_STARTED;
goto error;
+ } else {
+ /*
+ * If stopped, just make sure we've started before else the above call
+ * will always send that there is data pending.
+ *
+ * The consumer assumes that when the data pending command is received,
+ * the trace has been started before or else no output data is written
+ * by the streams which is a condition for data pending. So, this is
+ * *VERY* important that we don't ask the consumer before a start
+ * trace.
+ */
+ if (!session->has_been_started) {
+ ret = 0;
+ goto error;
+ }
}
if (ksess && ksess->consumer) {
ret = ust_app_snapshot_record(usess, output, wait, nb_streams);
if (ret < 0) {
- if (ret == -EINVAL) {
+ switch (-ret) {
+ case EINVAL:
ret = LTTNG_ERR_INVALID;
- goto error_snapshot;
+ break;
+ case ENODATA:
+ ret = LTTNG_ERR_SNAPSHOT_NODATA;
+ break;
+ default:
+ ret = LTTNG_ERR_SNAPSHOT_FAIL;
+ break;
}
-
- ret = LTTNG_ERR_SNAPSHOT_FAIL;
goto error_snapshot;
}
}
/* The session needs to be started at least once. */
- if (!session->started) {
+ if (!session->has_been_started) {
ret = LTTNG_ERR_START_SESSION_ONCE;
goto error;
}