This is a note to let you know that I've just added the patch titled
tracing: Do not stop recording cmdlines when tracing is off
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-do-not-stop-recording-cmdlines-when-tracing-is-off.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 85550c83da421fb12dc1816c45012e1e638d2b38 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Date: Thu, 17 Jun 2021 13:47:25 -0400
Subject: tracing: Do not stop recording cmdlines when tracing is off
From: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
commit 85550c83da421fb12dc1816c45012e1e638d2b38 upstream.
The saved_cmdlines is used to map pids to the task name, such that the
output of the tracing does not just show pids, but also gives a human
readable name for the task.
If the name is not mapped, the output looks like this:
<...>-1316 [005] ...2 132.044039: ...
Instead of this:
gnome-shell-1316 [005] ...2 132.044039: ...
The names are updated when tracing is running, but are skipped if tracing
is stopped. Unfortunately, this stops the recording of the names if the
top level tracer is stopped, and not if there's other tracers active.
The recording of a name only happens when a new event is written into a
ring buffer, so there is no need to test if tracing is on or not. If
tracing is off, then no event is written and no need to test if tracing is
off or not.
Remove the check, as it hides the names of tasks for events in the
instance buffers.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 7ffbd48d5cab2 ("tracing: Cache comms only after an event occurred")
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 3 ---
1 file changed, 3 deletions(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1635,9 +1635,6 @@ void trace_find_cmdline(int pid, char co
void tracing_record_cmdline(struct task_struct *tsk)
{
- if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
- return;
-
if (!__this_cpu_read(trace_cmdline_save))
return;
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-4.4/tracing-do-no-increment-trace_clock_global-by-one.patch
queue-4.4/tracing-do-not-stop-recording-cmdlines-when-tracing-is-off.patch
queue-4.4/tracing-do-not-stop-recording-comms-if-the-trace-file-is-being-read.patch
