Commit 977c1f9c authored Nov 07, 2016 by Alexei Starovoitov Committed by Steven Rostedt Nov 14, 2016

ftrace: Ignore FTRACE_FL_DISABLED while walking dyn_ftrace records

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



Cc: stable@vger.kernel.org
Fixes: b7ffffbb "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>

parent a25f0944

kernel/trace/ftrace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2763,7 +2763,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
		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();