Patch "tracing: Exclude 'generic fields' from histograms" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

tracing: Exclude 'generic fields' from histograms

to the 4.9-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-exclude-generic-fields-from-histograms.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Tom Zanussi <[email protected]>
Date: Fri, 22 Sep 2017 14:58:17 -0500
Subject: tracing: Exclude 'generic fields' from histograms

From: Tom Zanussi <[email protected]>

[ Upstream commit a15f7fc20389a8827d5859907568b201234d4b79 ]

There are a small number of 'generic fields' (comm/COMM/cpu/CPU) that are found by trace_find_event_field() but are only meant for filtering. Specifically, they unlike normal fields, they have a size of 0 and thus wreak havoc when used as a histogram key.

Exclude these (return -EINVAL) when used as histogram keys.

---
 kernel/trace/trace_events_hist.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -449,7 +449,7 @@ static int create_val_field(struct hist_
 	}
 
 	field = trace_find_event_field(file->event_call, field_name);
-	if (!field) {
+	if (!field || !field->size) {
 		ret = -EINVAL;
 		goto out;
 	}

@@ -547,7 +547,7 @@ static int create_key_field(struct hist_
 		}
 
 		field = trace_find_event_field(file->event_call, field_name);
-		if (!field) {
+		if (!field || !field->size) {
 			ret = -EINVAL;
 			goto out;
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/tracing-exclude-generic-fields-from-histograms.patch