Patch "ftrace: Ignore FTRACE_FL_DISABLED while walking dyn_ftrace records" has been added to the 4.8-stable tree

Patch "ftrace: Ignore FTRACE_FL_DISABLED while walking dyn_ftrace records" has been added to the 4.8-stable tree

[gregkh]

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

    ftrace: Ignore FTRACE_FL_DISABLED while walking dyn_ftrace records

to the 4.8-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-ignore-ftrace_fl_disabled-while-walking-dyn_ftrace-records.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 977c1f9c8c022d0173181766b34a0db3705265a4 Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast@fb.com>
Date: Mon, 7 Nov 2016 15:14:20 -0800
Subject: ftrace: Ignore FTRACE_FL_DISABLED while walking dyn_ftrace records

From: Alexei Starovoitov <ast@fb.com>

commit 977c1f9c8c022d0173181766b34a0db3705265a4 upstream.

ftrace_shutdown() checks for sanity of ftrace records
and if dyn_ftrace->flags is not zero, it will warn.
It can happen that 'flags' are set to FTRACE_FL_DISABLED at this point,
since some module was loaded, but before ftrace_module_enable()
cleared the flags for this module.

In other words the module.c is doing:
ftrace_module_init(mod); // calls ftrace_update_code() that sets flags=FTRACE_FL_DISABLED
... // here ftrace_shutdown() is called that warns, since
err = prepare_coming_module(mod); // didn't have a chance to clear FTRACE_FL_DISABLED

Fix it by ignoring disabled records.
It's similar to what __ftrace_hash_rec_update() is already doing.

Link: http://lkml.kernel.org/r/1478560460-3818619-1-git-send-email-ast@fb.com

Fixes: b7ffffbb46f2 "ftrace: Add infrastructure for delayed enabling of module functions"
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/ftrace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2757,7 +2757,7 @@ static int ftrace_shutdown(struct ftrace
 		struct dyn_ftrace *rec;
 
 		do_for_each_ftrace_rec(pg, rec) {
-			if (FTRACE_WARN_ON_ONCE(rec->flags))
+			if (FTRACE_WARN_ON_ONCE(rec->flags & ~FTRACE_FL_DISABLED))
 				pr_warn("  %pS flags:%lx\n",
 					(void *)rec->ip, rec->flags);
 		} while_for_each_ftrace_rec();


Patches currently in stable-queue which might be from ast@fb.com are

queue-4.8/ftrace-ignore-ftrace_fl_disabled-while-walking-dyn_ftrace-records.patch