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Commit 8c717b72 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

* 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timer: Use debugobjects to catch deletion of uninitialized timers
  timer: Setup uninitialized timer with a stub callback
  debugobjects: Extend to assert that an object is initialized
  debugobjects: Be smarter about static objects
parents 07d106d0 dc4218bd

Documentation/DocBook/debugobjects.tmpl

+50 −0
Original line number Diff line number Diff line
@@ -96,6 +96,7 @@ 
	<listitem><para>debug_object_deactivate</para></listitem>

	<listitem><para>debug_object_destroy</para></listitem>

	<listitem><para>debug_object_free</para></listitem>

	<listitem><para>debug_object_assert_init</para></listitem>

      </itemizedlist>

      Each of these functions takes the address of the real object and

      a pointer to the object type specific debug description
@@ -273,6 +274,26 @@ 
	debug checks.

      </para>

    </sect1>



    <sect1 id="debug_object_assert_init">

      <title>debug_object_assert_init</title>

      <para>

	This function is called to assert that an object has been

	initialized.

      </para>

      <para>

	When the real object is not tracked by debugobjects, it calls

	fixup_assert_init of the object type description structure

	provided by the caller, with the hardcoded object state

	ODEBUG_NOT_AVAILABLE. The fixup function can correct the problem

	by calling debug_object_init and other specific initializing

	functions.

      </para>

      <para>

	When the real object is already tracked by debugobjects it is

	ignored.

      </para>

    </sect1>

  </chapter>

  <chapter id="fixupfunctions">

    <title>Fixup functions</title>
@@ -381,6 +402,35 @@ 
	statistics.

      </para>

    </sect1>

    <sect1 id="fixup_assert_init">

      <title>fixup_assert_init</title>

      <para>

	This function is called from the debug code whenever a problem

	in debug_object_assert_init is detected.

      </para>

      <para>

	Called from debug_object_assert_init() with a hardcoded state

	ODEBUG_STATE_NOTAVAILABLE when the object is not found in the

	debug bucket.

      </para>

      <para>

	The function returns 1 when the fixup was successful,

	otherwise 0. The return value is used to update the

	statistics.

      </para>

      <para>

	Note, this function should make sure debug_object_init() is

	called before returning.

      </para>

      <para>

	The handling of statically initialized objects is a special

	case. The fixup function should check if this is a legitimate

	case of a statically initialized object or not. In this case only

	debug_object_init() should be called to make the object known to

	the tracker. Then the function should return 0 because this is not

	a real fixup.

      </para>

    </sect1>

  </chapter>

  <chapter id="bugs">

    <title>Known Bugs And Assumptions</title>

include/linux/debugobjects.h

+6 −0
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ struct debug_obj { 
 *			fails

 * @fixup_free:		fixup function, which is called when the free check

 *			fails

 * @fixup_assert_init:  fixup function, which is called when the assert_init

 *			check fails

 */

struct debug_obj_descr {

	const char		*name;
@@ -54,6 +56,7 @@ struct debug_obj_descr { 
	int (*fixup_activate)	(void *addr, enum debug_obj_state state);

	int (*fixup_destroy)	(void *addr, enum debug_obj_state state);

	int (*fixup_free)	(void *addr, enum debug_obj_state state);

	int (*fixup_assert_init)(void *addr, enum debug_obj_state state);

};



#ifdef CONFIG_DEBUG_OBJECTS
@@ -64,6 +67,7 @@ extern void debug_object_activate (void *addr, struct debug_obj_descr *descr); 
extern void debug_object_deactivate(void *addr, struct debug_obj_descr *descr);

extern void debug_object_destroy   (void *addr, struct debug_obj_descr *descr);

extern void debug_object_free      (void *addr, struct debug_obj_descr *descr);

extern void debug_object_assert_init(void *addr, struct debug_obj_descr *descr);



/*

 * Active state:
@@ -89,6 +93,8 @@ static inline void 
debug_object_destroy   (void *addr, struct debug_obj_descr *descr) { }

static inline void

debug_object_free      (void *addr, struct debug_obj_descr *descr) { }

static inline void

debug_object_assert_init(void *addr, struct debug_obj_descr *descr) { }



static inline void debug_objects_early_init(void) { }

static inline void debug_objects_mem_init(void) { }

kernel/timer.c

+56 −6
Original line number Diff line number Diff line
@@ -427,6 +427,12 @@ static int timer_fixup_init(void *addr, enum debug_obj_state state) 
	}

}



/* Stub timer callback for improperly used timers. */

static void stub_timer(unsigned long data)

{

	WARN_ON(1);

}



/*

 * fixup_activate is called when:

 * - an active object is activated
@@ -450,7 +456,8 @@ static int timer_fixup_activate(void *addr, enum debug_obj_state state) 
			debug_object_activate(timer, &timer_debug_descr);

			return 0;

		} else {

			WARN_ON_ONCE(1);

			setup_timer(timer, stub_timer, 0);

			return 1;

		}

		return 0;
@@ -480,12 +487,40 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state) 
	}

}



/*

 * fixup_assert_init is called when:

 * - an untracked/uninit-ed object is found

 */

static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)

{

	struct timer_list *timer = addr;



	switch (state) {

	case ODEBUG_STATE_NOTAVAILABLE:

		if (timer->entry.prev == TIMER_ENTRY_STATIC) {

			/*

			 * This is not really a fixup. The timer was

			 * statically initialized. We just make sure that it

			 * is tracked in the object tracker.

			 */

			debug_object_init(timer, &timer_debug_descr);

			return 0;

		} else {

			setup_timer(timer, stub_timer, 0);

			return 1;

		}

	default:

		return 0;

	}

}



static struct debug_obj_descr timer_debug_descr = {

	.name			= "timer_list",

	.debug_hint		= timer_debug_hint,

	.fixup_init		= timer_fixup_init,

	.fixup_activate		= timer_fixup_activate,

	.fixup_free		= timer_fixup_free,

	.fixup_assert_init	= timer_fixup_assert_init,

};



static inline void debug_timer_init(struct timer_list *timer)
@@ -508,6 +543,11 @@ static inline void debug_timer_free(struct timer_list *timer) 
	debug_object_free(timer, &timer_debug_descr);

}



static inline void debug_timer_assert_init(struct timer_list *timer)

{

	debug_object_assert_init(timer, &timer_debug_descr);

}



static void __init_timer(struct timer_list *timer,

			 const char *name,

			 struct lock_class_key *key);
@@ -531,6 +571,7 @@ EXPORT_SYMBOL_GPL(destroy_timer_on_stack); 
static inline void debug_timer_init(struct timer_list *timer) { }

static inline void debug_timer_activate(struct timer_list *timer) { }

static inline void debug_timer_deactivate(struct timer_list *timer) { }

static inline void debug_timer_assert_init(struct timer_list *timer) { }

#endif



static inline void debug_init(struct timer_list *timer)
@@ -552,6 +593,11 @@ static inline void debug_deactivate(struct timer_list *timer) 
	trace_timer_cancel(timer);

}



static inline void debug_assert_init(struct timer_list *timer)

{

	debug_timer_assert_init(timer);

}



static void __init_timer(struct timer_list *timer,

			 const char *name,

			 struct lock_class_key *key)
@@ -902,6 +948,8 @@ int del_timer(struct timer_list *timer) 
	unsigned long flags;

	int ret = 0;



	debug_assert_init(timer);



	timer_stats_timer_clear_start_info(timer);

	if (timer_pending(timer)) {

		base = lock_timer_base(timer, &flags);
@@ -932,6 +980,8 @@ int try_to_del_timer_sync(struct timer_list *timer) 
	unsigned long flags;

	int ret = -1;



	debug_assert_init(timer);



	base = lock_timer_base(timer, &flags);



	if (base->running_timer == timer)

lib/debugobjects.c

+50 −4
Original line number Diff line number Diff line
@@ -268,12 +268,16 @@ static void debug_print_object(struct debug_obj *obj, char *msg) 
 * Try to repair the damage, so we have a better chance to get useful

 * debug output.

 */

static void

static int

debug_object_fixup(int (*fixup)(void *addr, enum debug_obj_state state),

		   void * addr, enum debug_obj_state state)

{

	int fixed = 0;



	if (fixup)

		debug_objects_fixups += fixup(addr, state);

		fixed = fixup(addr, state);

	debug_objects_fixups += fixed;

	return fixed;

}



static void debug_object_is_on_stack(void *addr, int onstack)
@@ -386,6 +390,9 @@ void debug_object_activate(void *addr, struct debug_obj_descr *descr) 
	struct debug_bucket *db;

	struct debug_obj *obj;

	unsigned long flags;

	struct debug_obj o = { .object = addr,

			       .state = ODEBUG_STATE_NOTAVAILABLE,

			       .descr = descr };



	if (!debug_objects_enabled)

		return;
@@ -425,8 +432,9 @@ void debug_object_activate(void *addr, struct debug_obj_descr *descr) 
	 * let the type specific code decide whether this is

	 * true or not.

	 */

	debug_object_fixup(descr->fixup_activate, addr,

			   ODEBUG_STATE_NOTAVAILABLE);

	if (debug_object_fixup(descr->fixup_activate, addr,

			   ODEBUG_STATE_NOTAVAILABLE))

		debug_print_object(&o, "activate");

}



/**
@@ -562,6 +570,44 @@ out_unlock: 
	raw_spin_unlock_irqrestore(&db->lock, flags);

}



/**

 * debug_object_assert_init - debug checks when object should be init-ed

 * @addr:	address of the object

 * @descr:	pointer to an object specific debug description structure

 */

void debug_object_assert_init(void *addr, struct debug_obj_descr *descr)

{

	struct debug_bucket *db;

	struct debug_obj *obj;

	unsigned long flags;



	if (!debug_objects_enabled)

		return;



	db = get_bucket((unsigned long) addr);



	raw_spin_lock_irqsave(&db->lock, flags);



	obj = lookup_object(addr, db);

	if (!obj) {

		struct debug_obj o = { .object = addr,

				       .state = ODEBUG_STATE_NOTAVAILABLE,

				       .descr = descr };



		raw_spin_unlock_irqrestore(&db->lock, flags);

		/*

		 * Maybe the object is static.  Let the type specific

		 * code decide what to do.

		 */

		if (debug_object_fixup(descr->fixup_assert_init, addr,

				       ODEBUG_STATE_NOTAVAILABLE))

			debug_print_object(&o, "assert_init");

		return;

	}



	raw_spin_unlock_irqrestore(&db->lock, flags);

}



/**

 * debug_object_active_state - debug checks object usage state machine

 * @addr:	address of the object