Fix: ambiguous ownership of kernel context by multiple channels

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

diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index 9c3a394edbcb7e8e37bb379ebbdbea2e1f915876..a2f022886306ccb55e9c72a4751d896d6c3f9ae2 100644 (file)
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -34,6 +34,8 @@
 
 /*
  * Add kernel context to all channel.
+ *
+ * Assumes the ownership of kctx.
  */
 static int add_kctx_all_channels(struct ltt_kernel_session *ksession,
                struct ltt_kernel_context *kctx)
@@ -48,7 +50,17 @@ static int add_kctx_all_channels(struct ltt_kernel_session *ksession,
 
        /* Go over all channels */
        cds_list_for_each_entry(kchan, &ksession->channel_list.head, list) {
-               ret = kernel_add_channel_context(kchan, kctx);
+               struct ltt_kernel_context *kctx_copy;
+
+               kctx_copy = trace_kernel_copy_context(kctx);
+               if (!kctx_copy) {
+                       PERROR("zmalloc ltt_kernel_context");
+                       goto error;
+               }
+
+               /* Ownership of kctx_copy is transferred to the callee. */
+               ret = kernel_add_channel_context(kchan, kctx_copy);
+               kctx_copy = NULL;
                if (ret != 0) {
                        goto error;
                }
@@ -57,11 +69,14 @@ static int add_kctx_all_channels(struct ltt_kernel_session *ksession,
        ret = LTTNG_OK;
 
 error:
+       trace_kernel_destroy_context(kctx);
        return ret;
 }
 
 /*
  * Add kernel context to a specific channel.
+ *
+ * Assumes the ownership of kctx.
  */
 static int add_kctx_to_channel(struct ltt_kernel_context *kctx,
                struct ltt_kernel_channel *kchan)
@@ -73,7 +88,9 @@ static int add_kctx_to_channel(struct ltt_kernel_context *kctx,
 
        DBG("Add kernel context to channel '%s'", kchan->channel->name);
 
+       /* Ownership of kctx is transferred to the callee. */
        ret = kernel_add_channel_context(kchan, kctx);
+       kctx = NULL;
        if (ret != 0) {
                goto error;
        }
@@ -254,6 +271,8 @@ int context_kernel_add(struct ltt_kernel_session *ksession,
 
        if (*channel_name == '\0') {
                ret = add_kctx_all_channels(ksession, kctx);
+               /* Ownership of kctx is transferred to the callee. */
+               kctx = NULL;
                if (ret != LTTNG_OK) {
                        goto error;
                }
@@ -266,12 +285,14 @@ int context_kernel_add(struct ltt_kernel_session *ksession,
                }
 
                ret = add_kctx_to_channel(kctx, kchan);
+               /* Ownership of kctx is transferred to the callee. */
+               kctx = NULL;
                if (ret != LTTNG_OK) {
                        goto error;
                }
        }
 
-       return LTTNG_OK;
+       ret = LTTNG_OK;
 
 error:
        if (kctx) {