Fix: no-output sessions do not enforce snapshot constraints

[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 0330186209268cb63b49175e08d4a4102d07e96a..9cbadc6dde53fd16afde8b7a31cd6c4b15ac39cf 100644 (file)
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1523,6 +1523,11 @@ int cmd_enable_channel(struct ltt_session *session,
                kchan = trace_kernel_get_channel_by_name(attr->name,
                                session->kernel_session);
                if (kchan == NULL) {
+                       if (session->snapshot.nb_output > 0 ||
+                                       session->snapshot_mode) {
+                               /* Enforce mmap output for snapshot sessions. */
+                               attr->attr.output = LTTNG_EVENT_MMAP;
+                       }
                        ret = channel_kernel_create(session->kernel_session, attr, wpipe);
                        if (attr->name[0] != '\0') {
                                session->kernel_session->has_non_default_channel = 1;
@@ -1591,6 +1596,9 @@ int cmd_enable_channel(struct ltt_session *session,
                goto error;
        }
 
+       if (ret == LTTNG_OK && attr->attr.output != LTTNG_EVENT_MMAP) {
+               session->has_non_mmap_channel = true;
+       }
 error:
        rcu_read_unlock();
 end:
@@ -3548,6 +3556,11 @@ int cmd_snapshot_add_output(struct ltt_session *session,
                goto error;
        }
 
+       if (session->has_non_mmap_channel) {
+               ret = LTTNG_ERR_SNAPSHOT_UNSUPPORTED;
+               goto error;
+       }
+
        /* Only one output is allowed until we have the "tee" feature. */
        if (session->snapshot.nb_output == 1) {
                ret = LTTNG_ERR_SNAPSHOT_OUTPUT_EXIST;