[PATCH 5.12 124/178] tracing: Do not stop recording comms if the trace file is being read

Greg Kroah-Hartman
2021-06-21T16:48:01Z

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

commit 4fdd595e4f9a1ff6d93ec702eaecae451cfc6591 upstream.

A while ago, when the "trace" file was opened, tracing was stopped, and
code was added to stop recording the comms to saved_cmdlines, for mapping
of the pids to the task name.

Code has been added that only records the comm if a trace event occurred,
and there's no reason to not trace it if the trace file is opened.

Cc: stable@vger.kernel.org
Fixes: 7ffbd48d5cab2 ("tracing: Cache comms only after an event occurred")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/trace/trace.c | 9 ---------
1 file changed, 9 deletions(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2198,9 +2198,6 @@ struct saved_cmdlines_buffer {
};
static struct saved_cmdlines_buffer *savedcmd;

-/* temporary disable recording */
-static atomic_t trace_record_taskinfo_disabled __read_mostly;
-
static inline char *get_saved_cmdlines(int idx)
{
return &savedcmd->saved_cmdlines[idx * TASK_COMM_LEN];
@@ -3740,9 +3737,6 @@ static void *s_start(struct seq_file *m,
return ERR_PTR(-EBUSY);
#endif

- if (!iter->snapshot)
- atomic_inc(&trace_record_taskinfo_disabled);
-
if (*pos != iter->pos) {
iter->ent = NULL;
iter->cpu = 0;
@@ -3785,9 +3779,6 @@ static void s_stop(struct seq_file *m, v
return;
#endif

- if (!iter->snapshot)
- atomic_dec(&trace_record_taskinfo_disabled);
-
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
}