Fix: ambiguous ownership of kernel context by multiple channels

[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 dee065460b1e661f8dca9f32a9070f3b876b24bc..8dc3f86314d5aab8b94bf623942ec1ee404ad959 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -37,6 +37,8 @@
 
 /*
  * Add context on a kernel channel.
+ *
+ * Assumes the ownership of ctx.
  */
 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
                struct ltt_kernel_context *ctx)
@@ -67,9 +69,11 @@ int kernel_add_channel_context(struct ltt_kernel_channel *chan,
 
 end:
        cds_list_add_tail(&ctx->list, &chan->ctx_list);
-       return 0;
-
+       ctx = NULL;
 error:
+       if (ctx) {
+               trace_kernel_destroy_context(ctx);
+       }
        return ret;
 }
 
@@ -666,17 +670,22 @@ 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) {
@@ -695,13 +704,10 @@ 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);
        }