FAILED: patch "[PATCH] tracing: Do not stop recording comms if the trace file is" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jun 21, 2021

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Stable branch Tracing

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2021-06-21 10:41 UTC #0 lore raw

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4fdd595e4f9a1ff6d93ec702eaecae451cfc6591 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <[email protected]>
Date: Thu, 17 Jun 2021 14:32:34 -0400
Subject: [PATCH] tracing: Do not stop recording comms if the trace file is
being read

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 [email protected]

Fixes 7ffbd48d5cab2 ("tracing: Cache comms only after an event occurred")

Signed-off-by Steven Rostedt (VMware) <[email protected]>

kernel/trace/trace.c +0 -9

index e220b37e29c6..d23a09d3eb37 100644
@@ -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];

@@ -3996,9 +3993,6 @@ static void *s_start(struct seq_file *m, loff_t *pos)
 		return ERR_PTR(-EBUSY);
 #endif
 
-	if (!iter->snapshot)
-		atomic_inc(&trace_record_taskinfo_disabled);
-
 	if (*pos != iter->pos) {
 		iter->ent = NULL;
 		iter->cpu = 0;

@@ -4041,9 +4035,6 @@ static void s_stop(struct seq_file *m, void *p)
 		return;
 #endif
 
-	if (!iter->snapshot)
-		atomic_dec(&trace_record_taskinfo_disabled);
-
 	trace_access_unlock(iter->cpu_file);
 	trace_event_read_unlock();
 }