Patch "tracing: Call clear_boot_tracer() at lateinit_sync" 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: Call clear_boot_tracer() at lateinit_sync

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-call-clear_boot_tracer-at-lateinit_sync.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: "Steven Rostedt (VMware)" <[email protected]>
Date: Tue, 1 Aug 2017 12:01:52 -0400
Subject: tracing: Call clear_boot_tracer() at lateinit_sync

From: Steven Rostedt (VMware) <[email protected]>

commit 4bb0f0e73c8c30917d169c4a0f1ac083690c545b upstream.

The clear_boot_tracer function is used to reset the default_bootup_tracer string to prevent it from being accessed after boot, as it originally points to init data. But since clear_boot_tracer() is called via the init_lateinit() call, it races with the initcall for registering the hwlat tracer. If someone adds "ftrace=hwlat" to the kernel command line, depending on how the linker sets up the text, the saved command line may be cleared, and the hwlat tracer never is initialized.

Simply have the clear_boot_tracer() be called by initcall_lateinit_sync() as that's for tasks to be called after lateinit.

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

@@ -7767,4 +7767,4 @@ __init static int clear_boot_tracer(void
 }
 
 fs_initcall(tracer_init_tracefs);
-late_initcall(clear_boot_tracer);
+late_initcall_sync(clear_boot_tracer);

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

queue-4.9/ftrace-check-for-null-ret_stack-on-profile-function-graph-entry-function.patch queue-4.9/tracing-fix-freeing-of-filter-in-create_filter-when-set_str-is-false.patch queue-4.9/tracing-call-clear_boot_tracer-at-lateinit_sync.patch queue-4.9/tracing-fix-kmemleak-in-tracing_map_array_free.patch