Eric Lee / smarc-ti-linux-kernel | Embedian Git Server

Commit 409b0c0169147e8e392886ca441cc95e314b5faf

Authored by Steven Rostedt (Red Hat) 2015-02-07 03:30:50 +0800

Committed by Greg Kroah-Hartman 2015-02-11 15:00:56 +0800

tracing: Add condition check to RCU lockdep checks

commit a05d59a5673339ef6936d6940cdf68172ce75b9f upstream.

The trace_tlb_flush() tracepoint can be called when a CPU is going offline.
When a CPU is offline, RCU is no longer watching that CPU and since the
tracepoint is protected by RCU, it must not be called. To prevent the
tlb_flush tracepoint from being called when the CPU is offline, it was
converted to a TRACE_EVENT_CONDITION where the condition checks if the
CPU is online before calling the tracepoint.

Unfortunately, this was not enough to stop lockdep from complaining about
it. Even though the RCU protected code of the tracepoint will never be
called, the condition is hidden within the tracepoint, and even though the
condition prevents RCU code from being called, the lockdep checks are
outside the tracepoint (this is to test tracepoints even when they are not
enabled).

Even though tracepoints should be checked to be RCU safe when they are not
enabled, the condition should still be considered when checking RCU.

Link: http://lkml.kernel.org/r/CA+icZUUGiGDoL5NU8RuxKzFjoLjEKRtUWx=JB8B9a0EQv-eGzQ@mail.gmail.com

Fixes: 3a630178fd5f "tracing: generate RCU warnings even when tracepoints are disabled"
Acked-by: Dave Hansen <dave@sr71.net>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 1 additions and 1 deletions Inline Diff

include/linux/tracepoint.h

include/linux/tracepoint.h

Diff comments View file @ 409b0c0

1	#ifndef _LINUX_TRACEPOINT_H	1	#ifndef _LINUX_TRACEPOINT_H
2	#define _LINUX_TRACEPOINT_H	2	#define _LINUX_TRACEPOINT_H
3		3
4	/*	4	/*
5	* Kernel Tracepoint API.	5	* Kernel Tracepoint API.
6	*	6	*
7	* See Documentation/trace/tracepoints.txt.	7	* See Documentation/trace/tracepoints.txt.
8	*	8	*
9	* Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>	9	* Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10	*	10	*
11	* Heavily inspired from the Linux Kernel Markers.	11	* Heavily inspired from the Linux Kernel Markers.
12	*	12	*
13	* This file is released under the GPLv2.	13	* This file is released under the GPLv2.
14	* See the file COPYING for more details.	14	* See the file COPYING for more details.
15	*/	15	*/
16		16
17	#include <linux/errno.h>	17	#include <linux/errno.h>
18	#include <linux/types.h>	18	#include <linux/types.h>
19	#include <linux/rcupdate.h>	19	#include <linux/rcupdate.h>
20	#include <linux/static_key.h>	20	#include <linux/static_key.h>
21		21
22	struct module;	22	struct module;
23	struct tracepoint;	23	struct tracepoint;
24	struct notifier_block;	24	struct notifier_block;
25		25
26	struct tracepoint_func {	26	struct tracepoint_func {
27	void *func;	27	void *func;
28	void *data;	28	void *data;
29	};	29	};
30		30
31	struct tracepoint {	31	struct tracepoint {
32	const char name; / Tracepoint name */	32	const char name; / Tracepoint name */
33	struct static_key key;	33	struct static_key key;
34	void (*regfunc)(void);	34	void (*regfunc)(void);
35	void (*unregfunc)(void);	35	void (*unregfunc)(void);
36	struct tracepoint_func __rcu *funcs;	36	struct tracepoint_func __rcu *funcs;
37	};	37	};
38		38
39	extern int	39	extern int
40	tracepoint_probe_register(struct tracepoint tp, void probe, void *data);	40	tracepoint_probe_register(struct tracepoint tp, void probe, void *data);