Fix: ensure kernel context is in a list before trying to delete it

[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 e478499336896f5d739e087c8ee91e3a395886cd..2cbed381870a096350a4e8ac77ec39845850d0f1 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -36,6 +36,8 @@
 
 /*
  * 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)
@@ -63,12 +65,16 @@ int kernel_add_channel_context(struct ltt_kernel_channel *chan,
                        goto error;
                }
        }
+       ret = 0;
 
 end:
        cds_list_add_tail(&ctx->list, &chan->ctx_list);
-       return 0;
-
+       ctx->in_list = true;
+       ctx = NULL;
 error:
+       if (ctx) {
+               trace_kernel_destroy_context(ctx);
+       }
        return ret;
 }
 
@@ -1088,3 +1094,35 @@ int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits)
 
        return kernctl_syscall_mask(chan_fd, syscall_mask, nr_bits);
 }
+
+/*
+ * Check for the support of the RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS via abi
+ * version number.
+ *
+ * Return 1 on success, 0 when feature is not supported, negative value in case
+ * of errors.
+ */
+int kernel_supports_ring_buffer_snapshot_sample_positions(int tracer_fd)
+{
+       int ret = 0; // Not supported by default
+       struct lttng_kernel_tracer_abi_version abi;
+
+       ret = kernctl_tracer_abi_version(tracer_fd, &abi);
+       if (ret < 0) {
+               ERR("Failed to retrieve lttng-modules ABI version");
+               goto error;
+       }
+
+       /*
+        * RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS was introduced in 2.3
+        */
+       if (abi.major >= 2 && abi.minor >= 3) {
+               /* Supported */
+               ret = 1;
+       } else {
+               /* Not supported */
+               ret = 0;
+       }
+error:
+       return ret;
+}