[tip:core/locking] lockdep: Add statistics info for max bfs queue depth

[tip-bot for Ming Lei <tom.leiming@gmail.com>]

Commit-ID:  12f3dfd022d7e616757a94f0538d3d525d806a16
Gitweb:     http://git.kernel.org/tip/12f3dfd022d7e616757a94f0538d3d525d806a16
Author:     Ming Lei <tom.leiming@gmail.com>
AuthorDate: Thu, 16 Jul 2009 15:44:29 +0200
Committer:  Peter Zijlstra <a.p.zijlstra@chello.nl>
CommitDate: Fri, 24 Jul 2009 10:52:03 +0200

lockdep: Add statistics info for max bfs queue depth

Add BFS statistics to the existing lockdep stats.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1246201486-7308-10-git-send-email-tom.leiming@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 kernel/lockdep.c           |    6 +++++-
 kernel/lockdep_internals.h |    3 ++-
 kernel/lockdep_proc.c      |    2 ++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 6358cf7..744da62 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -929,7 +929,7 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
 
 unsigned long bfs_accessed[BITS_TO_LONGS(MAX_LOCKDEP_ENTRIES)];
 static struct circular_queue  lock_cq;
-
+unsigned int max_bfs_queue_depth;
 static int __bfs(struct lock_list *source_entry,
 			void *data,
 			int (*match)(struct lock_list *entry, void *data),
@@ -975,6 +975,7 @@ static int __bfs(struct lock_list *source_entry,
 
 		list_for_each_entry(entry, head, entry) {
 			if (!lock_accessed(entry)) {
+				unsigned int cq_depth;
 				mark_lock_accessed(entry, lock);
 				if (match(entry, data)) {
 					*target_entry = entry;
@@ -986,6 +987,9 @@ static int __bfs(struct lock_list *source_entry,
 					ret = -1;
 					goto exit;
 				}
+				cq_depth = __cq_get_elem_count(cq);
+				if (max_bfs_queue_depth < cq_depth)
+					max_bfs_queue_depth = cq_depth;
 			}
 		}
 	}
diff --git a/kernel/lockdep_internals.h b/kernel/lockdep_internals.h
index b115aaa..6baa880 100644
--- a/kernel/lockdep_internals.h
+++ b/kernel/lockdep_internals.h
@@ -138,6 +138,7 @@ extern atomic_t nr_find_usage_backwards_recursions;
 #endif
 
 
+extern unsigned int max_bfs_queue_depth;
 extern unsigned long nr_list_entries;
 extern struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
 extern unsigned long bfs_accessed[];
@@ -191,7 +192,7 @@ static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
 	return 0;
 }
 
-static inline int __cq_get_elem_count(struct circular_queue *cq)
+static inline unsigned int  __cq_get_elem_count(struct circular_queue *cq)
 {
 	return (cq->rear - cq->front)&(MAX_CIRCULAR_QUE_SIZE-1);
 }
diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index d7135aa..9a1bf34 100644
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -411,6 +411,8 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
 			max_lockdep_depth);
 	seq_printf(m, " max recursion depth:           %11u\n",
 			max_recursion_depth);
+	seq_printf(m, " max bfs queue depth:           %11u\n",
+			max_bfs_queue_depth);
 	lockdep_stats_debug_show(m);
 	seq_printf(m, " debug_locks:                   %11u\n",
 			debug_locks);