Commit 068135e6 authored by Jason Baron's avatar Jason Baron Committed by Linus Torvalds
Browse files

[PATCH] lockdep: add graph depth information to /proc/lockdep 



Generate locking graph information into /proc/lockdep, for lock hierarchy
documentation and visualization purposes.

sample output:

 c089fd5c OPS:     138 FD:   14 BD:    1 --..: &tty->termios_mutex
  -> [c07a3430] tty_ldisc_lock
  -> [c07a37f0] &port_lock_key
  -> [c07afdc0] &rq->rq_lock_key#2

The lock classes listed are all the first-hop lock dependencies that
lockdep has seen so far.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 381a2292

include/linux/lockdep.h

+1 −0
Original line number Diff line number Diff line
@@ -132,6 +132,7 @@ struct lock_list { 
	struct list_head		entry;

	struct lock_class		*class;

	struct stack_trace		trace;

	int				distance;

};



/*

kernel/lockdep.c

+12 −7
Original line number Diff line number Diff line
@@ -490,7 +490,7 @@ static void print_lock_dependencies(struct lock_class *class, int depth) 
 * Add a new dependency to the head of the list:

 */

static int add_lock_to_list(struct lock_class *class, struct lock_class *this,

			    struct list_head *head, unsigned long ip)

			    struct list_head *head, unsigned long ip, int distance)

{

	struct lock_list *entry;

	/*
@@ -502,6 +502,7 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this, 
		return 0;



	entry->class = this;

	entry->distance = distance;

	if (!save_trace(&entry->trace))

		return 0;
@@ -906,7 +907,7 @@ check_deadlock(struct task_struct *curr, struct held_lock *next, 
 */

static int

check_prev_add(struct task_struct *curr, struct held_lock *prev,

	       struct held_lock *next)

	       struct held_lock *next, int distance)

{

	struct lock_list *entry;

	int ret;
@@ -984,21 +985,25 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
	 *  L2 added to its dependency list, due to the first chain.)

	 */

	list_for_each_entry(entry, &prev->class->locks_after, entry) {

		if (entry->class == next->class)

		if (entry->class == next->class) {

			if (distance == 1)

				entry->distance = 1;

			return 2;

		}

	}



	/*

	 * Ok, all validations passed, add the new lock

	 * to the previous lock's dependency list:

	 */

	ret = add_lock_to_list(prev->class, next->class,

			       &prev->class->locks_after, next->acquire_ip);

			       &prev->class->locks_after, next->acquire_ip, distance);



	if (!ret)

		return 0;



	ret = add_lock_to_list(next->class, prev->class,

			       &next->class->locks_before, next->acquire_ip);

			       &next->class->locks_before, next->acquire_ip, distance);

	if (!ret)

		return 0;
@@ -1046,13 +1051,14 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next) 
		goto out_bug;



	for (;;) {

		int distance = curr->lockdep_depth - depth + 1;

		hlock = curr->held_locks + depth-1;

		/*

		 * Only non-recursive-read entries get new dependencies

		 * added:

		 */

		if (hlock->read != 2) {

			if (!check_prev_add(curr, hlock, next))

			if (!check_prev_add(curr, hlock, next, distance))

				return 0;

			/*

			 * Stop after the first non-trylock entry,
@@ -2779,4 +2785,3 @@ void debug_show_held_locks(struct task_struct *task) 
}



EXPORT_SYMBOL_GPL(debug_show_held_locks);

kernel/lockdep_proc.c

+29 −12
Original line number Diff line number Diff line
@@ -77,12 +77,29 @@ static unsigned long count_backward_deps(struct lock_class *class) 
	return ret;

}



static void print_name(struct seq_file *m, struct lock_class *class)

{

	char str[128];

	const char *name = class->name;



	if (!name) {

		name = __get_key_name(class->key, str);

		seq_printf(m, "%s", name);

	} else{

		seq_printf(m, "%s", name);

		if (class->name_version > 1)

			seq_printf(m, "#%d", class->name_version);

		if (class->subclass)

			seq_printf(m, "/%d", class->subclass);

	}

}



static int l_show(struct seq_file *m, void *v)

{

	unsigned long nr_forward_deps, nr_backward_deps;

	struct lock_class *class = m->private;

	char str[128], c1, c2, c3, c4;

	const char *name;

	struct lock_list *entry;

	char c1, c2, c3, c4;



	seq_printf(m, "%p", class->key);

#ifdef CONFIG_DEBUG_LOCKDEP
@@ -97,16 +114,16 @@ static int l_show(struct seq_file *m, void *v) 
	get_usage_chars(class, &c1, &c2, &c3, &c4);

	seq_printf(m, " %c%c%c%c", c1, c2, c3, c4);



	name = class->name;

	if (!name) {

		name = __get_key_name(class->key, str);

		seq_printf(m, ": %s", name);

	} else{

		seq_printf(m, ": %s", name);

		if (class->name_version > 1)

			seq_printf(m, "#%d", class->name_version);

		if (class->subclass)

			seq_printf(m, "/%d", class->subclass);

	seq_printf(m, ": ");

	print_name(m, class);

	seq_puts(m, "\n");



	list_for_each_entry(entry, &class->locks_after, entry) {

		if (entry->distance == 1) {

			seq_printf(m, " -> [%p] ", entry->class);

			print_name(m, entry->class);

			seq_puts(m, "\n");

		}

	}

	seq_puts(m, "\n");

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