Clarify kernel version check error messages

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

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index bf9f8b623288eb2e7eb58652bb5f26493ecf399e..dee065460b1e661f8dca9f32a9070f3b876b24bc 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -15,7 +15,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
 #define _LGPL_SOURCE
 #include <errno.h>
 #include <fcntl.h>
@@ -50,17 +49,24 @@ int kernel_add_channel_context(struct ltt_kernel_channel *chan,
        DBG("Adding context to channel %s", chan->channel->name);
        ret = kernctl_add_context(chan->fd, &ctx->ctx);
        if (ret < 0) {
-               if (errno != EEXIST) {
-                       PERROR("add context ioctl");
-               } else {
+               switch (errno) {
+               case ENOSYS:
+                       /* Exists but not available for this kernel */
+                       ret = LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE;
+                       goto error;
+               case EEXIST:
                        /* If EEXIST, we just ignore the error */
                        ret = 0;
+                       goto end;
+               default:
+                       PERROR("add context ioctl");
+                       ret = LTTNG_ERR_KERN_CONTEXT_FAIL;
+                       goto error;
                }
-               goto error;
        }
 
+end:
        cds_list_add_tail(&ctx->list, &chan->ctx_list);
-
        return 0;
 
 error:
@@ -177,7 +183,9 @@ error:
  * We own filter_expression and filter.
  */
 int kernel_create_event(struct lttng_event *ev,
-               struct ltt_kernel_channel *channel)
+               struct ltt_kernel_channel *channel,
+               char *filter_expression,
+               struct lttng_filter_bytecode *filter)
 {
        int ret;
        struct ltt_kernel_event *event;
@@ -185,7 +193,9 @@ int kernel_create_event(struct lttng_event *ev,
        assert(ev);
        assert(channel);
 
-       event = trace_kernel_create_event(ev);
+       /* We pass ownership of filter_expression and filter */
+       event = trace_kernel_create_event(ev, filter_expression,
+                       filter);
        if (event == NULL) {
                ret = -1;
                goto error;
@@ -217,6 +227,26 @@ int kernel_create_event(struct lttng_event *ev,
                PERROR("fcntl session fd");
        }
 
+       if (filter) {
+               ret = kernctl_filter(event->fd, filter);
+               if (ret) {
+                       goto filter_error;
+               }
+       }
+
+       ret = kernctl_enable(event->fd);
+       if (ret < 0) {
+               switch (errno) {
+               case EEXIST:
+                       ret = LTTNG_ERR_KERN_EVENT_EXIST;
+                       break;
+               default:
+                       PERROR("enable kernel event");
+                       break;
+               }
+               goto enable_error;
+       }
+
        /* Add event to event list */
        cds_list_add(&event->list, &channel->events_list.head);
        channel->event_count++;
@@ -225,6 +255,16 @@ int kernel_create_event(struct lttng_event *ev,
 
        return 0;
 
+enable_error:
+filter_error:
+       {
+               int closeret;
+
+               closeret = close(event->fd);
+               if (closeret) {
+                       PERROR("close event fd");
+               }
+       }
 free_event:
        free(event);
 error:
@@ -345,16 +385,46 @@ error:
 
 int kernel_track_pid(struct ltt_kernel_session *session, int pid)
 {
+       int ret;
+
        DBG("Kernel track PID %d for session id %" PRIu64 ".",
                        pid, session->id);
-       return kernctl_track_pid(session->fd, pid);
+       ret = kernctl_track_pid(session->fd, pid);
+       if (!ret) {
+               return LTTNG_OK;
+       }
+       switch (errno) {
+       case EINVAL:
+               return LTTNG_ERR_INVALID;
+       case ENOMEM:
+               return LTTNG_ERR_NOMEM;
+       case EEXIST:
+               return LTTNG_ERR_PID_TRACKED;
+       default:
+               return LTTNG_ERR_UNK;
+       }
 }
 
 int kernel_untrack_pid(struct ltt_kernel_session *session, int pid)
 {
+       int ret;
+
        DBG("Kernel untrack PID %d for session id %" PRIu64 ".",
                        pid, session->id);
-       return kernctl_untrack_pid(session->fd, pid);
+       ret = kernctl_untrack_pid(session->fd, pid);
+       if (!ret) {
+               return LTTNG_OK;
+       }
+       switch (errno) {
+       case EINVAL:
+               return LTTNG_ERR_INVALID;
+       case ENOMEM:
+               return LTTNG_ERR_NOMEM;
+       case ENOENT:
+               return LTTNG_ERR_PID_NOT_TRACKED;
+       default:
+               return LTTNG_ERR_UNK;
+       }
 }
 
 ssize_t kernel_list_tracker_pids(struct ltt_kernel_session *session,
@@ -766,7 +836,7 @@ int kernel_validate_version(int tracer_fd)
 
        ret = kernctl_tracer_version(tracer_fd, &version);
        if (ret < 0) {
-               ERR("Failed at getting the lttng-modules version");
+               ERR("Failed to retrieve the lttng-modules version");
                goto error;
        }
 
@@ -778,11 +848,11 @@ int kernel_validate_version(int tracer_fd)
        }
        ret = kernctl_tracer_abi_version(tracer_fd, &abi_version);
        if (ret < 0) {
-               ERR("Failed at getting lttng-modules ABI version");
+               ERR("Failed to retrieve lttng-modules ABI version");
                goto error;
        }
        if (abi_version.major != LTTNG_MODULES_ABI_MAJOR_VERSION) {
-               ERR("Kernel tracer ABI version (%d.%d) is not compatible with expected ABI major version (%d.*)",
+               ERR("Kernel tracer ABI version (%d.%d) does not match the expected ABI major version (%d.*)",
                        abi_version.major, abi_version.minor,
                        LTTNG_MODULES_ABI_MAJOR_VERSION);
                goto error;
@@ -796,6 +866,7 @@ error_version:
        ret = -1;
 
 error:
+       ERR("Kernel tracer version check failed; kernel tracing will not be available");
        return ret;
 }