[lttng-dev] [PATCH babeltrace 1.5] Use trace->trace_id for check to remove trace from bt_ctx

[Jonathan Rajotte]

Commit b9e6498df8b3e7c2ad312dccddf9f1a5e181648e remove the existence
guarantee of the trace_id hash table key by moving the trace->in_use
assignation before the assignation of trace_id and insertion into
the hash table.

Use the trade_id field value to validate if it should be
removed from the hash table.
A NULL trace_id field indicates that no insertion was performed.

This is mostly a workaround to a problem found in, at least, glib-2.28
where the g_hash_table_lookup_node abort on a SIGFPE signal due to
modulo by zero. The exact cause for this is unknown for now [1].
There is little reason for "mod" to be 0 at that point as explained in
the bug report.

Currently unable to reproduce.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1074401

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
---
 formats/lttng-live/lttng-live-comm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/formats/lttng-live/lttng-live-comm.c b/formats/lttng-live/lttng-live-comm.c
index 055b1c30..941d5c2f 100644
--- a/formats/lttng-live/lttng-live-comm.c
+++ b/formats/lttng-live/lttng-live-comm.c
@@ -1466,7 +1466,7 @@ int del_traces(gpointer key, gpointer value, gpointer user_data)
 		lvstream->in_trace = 0;
 		bt_list_del(&lvstream->trace_stream_node);
 	}
-	if (trace->in_use) {
+	if (trace->in_use && trace->trace_id) {
 		ret = bt_context_remove_trace(bt_ctx, trace->trace_id);
 		if (ret < 0)
 			fprintf(stderr, "[error] removing trace from context\n");
-- 
2.17.1