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>

3 files changed, 9 insertions, 2 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 6358cf7e84b2..744da6265d99 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 b115aaa0bf35..6baa8807efdd 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 d7135aa2d2c4..9a1bf34d2ff6 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);