Commit-ID:  70911fdc9576f4eeb3986689a1c9a778a4a4aacb
Gitweb:     http://git.kernel.org/tip/70911fdc9576f4eeb3986689a1c9a778a4a4aacb
Author:     Byungchul Park <byungchul.p...@lge.com>
AuthorDate: Mon, 7 Aug 2017 16:12:50 +0900
Committer:  Ingo Molnar <mi...@kernel.org>
CommitDate: Thu, 10 Aug 2017 12:29:06 +0200

locking/lockdep: Change the meaning of check_prev_add()'s return value

Firstly, return 1 instead of 2 when 'prev -> next' dependency already
exists. Since the value 2 is not referenced anywhere, just return 1
indicating success in this case.

Secondly, return 2 instead of 1 when successfully added a lock_list
entry with saving stack_trace. With that, a caller can decide whether
to avoid redundant save_trace() on the caller site.

Signed-off-by: Byungchul Park <byungchul.p...@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: a...@linux-foundation.org
Cc: boqun.f...@gmail.com
Cc: kernel-t...@lge.com
Cc: kir...@shutemov.name
Cc: npig...@gmail.com
Cc: wal...@google.com
Cc: wi...@infradead.org
Link: 
http://lkml.kernel.org/r/1502089981-21272-4-git-send-email-byungchul.p...@lge.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
 kernel/locking/lockdep.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index bdf6b31..7cf02fa 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1881,7 +1881,7 @@ check_prev_add(struct task_struct *curr, struct held_lock 
*prev,
                if (entry->class == hlock_class(next)) {
                        if (distance == 1)
                                entry->distance = 1;
-                       return 2;
+                       return 1;
                }
        }
 
@@ -1935,9 +1935,10 @@ check_prev_add(struct task_struct *curr, struct 
held_lock *prev,
                print_lock_name(hlock_class(next));
                printk(KERN_CONT "\n");
                dump_stack();
-               return graph_lock();
+               if (!graph_lock())
+                       return 0;
        }
-       return 1;
+       return 2;
 }
 
 /*

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