return ret;
}
+static int channel_validate(struct lttng_channel *attr)
+{
+ /*
+ * The ringbuffer (both in user space and kernel) behaves badly
+ * in overwrite mode and with less than 2 subbuffers so block it
+ * right away and send back an invalid attribute error.
+ */
+ if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
+ return -1;
+ }
+ return 0;
+}
+
/*
* Create kernel channel of the kernel session and notify kernel thread.
*/
attr = defattr;
}
+ /*
+ * Set the overwrite mode for this channel based on the session
+ * type unless the client explicitly overrides the channel mode.
+ */
+ if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
+ attr->attr.overwrite = !!ksession->snapshot_mode;
+ }
+
+ /* Enforce mmap output for snapshot sessions. */
if (ksession->snapshot_mode) {
- /* Force channel attribute for snapshot mode. */
- attr->attr.overwrite = 1;
attr->attr.output = LTTNG_EVENT_MMAP;
}
+ /* Validate common channel properties. */
+ if (channel_validate(attr) < 0) {
+ ret = LTTNG_ERR_INVALID;
+ goto error;
+ }
+
/* Channel not found, creating it */
ret = kernel_create_channel(ksession, attr);
if (ret < 0) {
}
}
+ /*
+ * Set the overwrite mode for this channel based on the session
+ * type unless the client explicitly overrides the channel mode.
+ */
+ if (attr->attr.overwrite == DEFAULT_CHANNEL_OVERWRITE) {
+ attr->attr.overwrite = !!usess->snapshot_mode;
+ }
+
+ /* Enforce mmap output for snapshot sessions. */
if (usess->snapshot_mode) {
- /* Force channel attribute for snapshot mode. */
- attr->attr.overwrite = 1;
attr->attr.output = LTTNG_EVENT_MMAP;
}
+ /* Validate common channel properties. */
+ if (channel_validate(attr) < 0) {
+ ret = LTTNG_ERR_INVALID;
+ goto error;
+ }
+
/*
* Validate UST buffer size and number of buffers: must both be power of 2
* and nonzero. We validate right here for UST, because applications will