From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
If the -o comes after a -B, the output_file name will be associated to the
trace instance of that -B, and the top_instance.output_file will be NULL.
If recording is started in a location that is read-only, the temp file
created for the top instance is going to try to be created in that read-only
file system.
/sys/kernel/tracing# trace-cmd record -o /tmp/test.dat -B test -e sched
Hit Ctrl^C to stop recording
^Ctrace-cmd: Permission denied
could not create file (null).cpu0
Make sure all instances, including the top_instance has their output_file
correct.
Also, because the output file could have been created under another
instance, check if that instance already has the output file before
assigning over it.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
tracecmd/trace-record.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 762afba4..91cc90d4 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -7122,6 +7122,10 @@ static void record_trace(int argc, char **argv,
if (!ctx->output)
ctx->output = DEFAULT_INPUT_FILE;
+ /* Make sure top_instance.output_file exists */
+ if (!top_instance.output_file)
+ top_instance.output_file = strdup(ctx->output);
+
if (ctx->data_flags & (DATA_FL_GUEST | DATA_FL_PROXY))
set_tsync_params(ctx);
@@ -7131,7 +7135,9 @@ static void record_trace(int argc, char **argv,
for_all_instances(instance) {
if (ctx->temp)
instance->temp_dir = ctx->temp;
- instance->output_file = strdup(ctx->output);
+ /* The -o could have been done after -B */
+ if (!instance->output_file)
+ instance->output_file = strdup(ctx->output);
if (!instance->output_file)
die("Failed to allocate output file name for instance");
if (!ctx->manual && instance->flags & BUFFER_FL_PROFILE)
--
2.43.0
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