Fix: lttng-sessiond: cpu hotplug stream number mismatch

[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 2cad0b2ab44b8bdd8ece486521e62f6654677e4d..78978a234a6d8cf53b5011aaf728340462b3206c 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -49,17 +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:
@@ -659,17 +666,22 @@ error:
  * Open stream of channel, register it to the kernel tracer and add it
  * to the stream list of the channel.
  *
+ * Note: given that the streams may appear in random order wrt CPU
+ * number (e.g. cpu hotplug), the index value of the stream number in
+ * the stream name is not necessarily linked to the CPU number.
+ *
  * Return the number of created stream. Else, a negative value.
  */
 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 {
-       int ret, count = 0;
+       int ret;
        struct ltt_kernel_stream *lks;
 
        assert(channel);
 
        while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
-               lks = trace_kernel_create_stream(channel->channel->name, count);
+               lks = trace_kernel_create_stream(channel->channel->name,
+                               channel->stream_count);
                if (lks == NULL) {
                        ret = close(ret);
                        if (ret) {
@@ -688,13 +700,10 @@ int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
                lks->tracefile_size = channel->channel->attr.tracefile_size;
                lks->tracefile_count = channel->channel->attr.tracefile_count;
 
-               /* Add stream to channe stream list */
+               /* Add stream to channel stream list */
                cds_list_add(&lks->list, &channel->stream_list.head);
                channel->stream_count++;
 
-               /* Increment counter which represent CPU number. */
-               count++;
-
                DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
                                lks->state);
        }
@@ -829,7 +838,7 @@ 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;
        }
 
@@ -841,11 +850,11 @@ 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;
@@ -859,6 +868,7 @@ error_version:
        ret = -1;
 
 error:
+       ERR("Kernel tracer version check failed; kernel tracing will not be available");
        return ret;
 }