lockdep: Fix missing entries in /proc/lock_chains

Two entries are missing in the output of /proc/lock_chains.

One is chains[1]. When lc_next() is called the 1st time,
chains[0] is returned. And when it's called the 2nd time,
chains[2] is returned.

The other missing ons is, when lc_start() is called the 2nd
time, we should start from chains[@pos-1] but not chains[@pos],
because pos == 0 is the header.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4A88ED25.2040306@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/lockdep_proc.c

@@ -160,8 +160,8 @@ static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
 	else {
 		chain = v;
 
-		if (*pos < nr_lock_chains)
-			chain = lock_chains + *pos;
+		if (*pos - 1 < nr_lock_chains)
+			chain = lock_chains + (*pos - 1);
 		else
 			chain = NULL;
 	}
@@ -174,8 +174,8 @@ static void *lc_start(struct seq_file *m, loff_t *pos)
 	if (*pos == 0)
 		return SEQ_START_TOKEN;
 
-	if (*pos < nr_lock_chains)
-		return lock_chains + *pos;
+	if (*pos - 1 < nr_lock_chains)
+		return lock_chains + (*pos - 1);
 
 	return NULL;
 }