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>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index 5dbe30b4e59..9a7996e371f 100644
--- a/kernel/lockdep_proc.c
+++ b/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;
 }