This is a note to let you know that I've just added the patch titled
ftrace: Handle commands when closing set_ftrace_filter file
to the 5.12-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:
ftrace-handle-commands-when-closing-set_ftrace_filter-file.patch
and it can be found in the queue-5.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Date: Wed, 5 May 2021 10:38:24 -0400
Subject: ftrace: Handle commands when closing set_ftrace_filter file
From: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
commit 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 upstream.
# echo switch_mm:traceoff > /sys/kernel/tracing/set_ftrace_filter
will cause switch_mm to stop tracing by the traceoff command.
# echo -n switch_mm:traceoff > /sys/kernel/tracing/set_ftrace_filter
does nothing.
The reason is that the parsing in the write function only processes
commands if it finished parsing (there is white space written after the
command). That's to handle:
write(fd, "switch_mm:", 10);
write(fd, "traceoff", 8);
cases, where the command is broken over multiple writes.
The problem is if the file descriptor is closed, then the write call is
not processed, and the command needs to be processed in the release code.
The release code can handle matching of functions, but does not handle
commands.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: eda1e32855656 ("tracing: handle broken names in ftrace filter")
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/ftrace.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5631,7 +5631,10 @@ int ftrace_regex_release(struct inode *i
parser = &iter->parser;
if (trace_parser_loaded(parser)) {
- ftrace_match_records(iter->hash, parser->buffer, parser->idx);
+ int enable = !(iter->flags & FTRACE_ITER_NOTRACE);
+
+ ftrace_process_regex(iter, parser->buffer,
+ parser->idx, enable);
}
trace_parser_put(parser);
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-5.12/ftrace-handle-commands-when-closing-set_ftrace_filter-file.patch
