Commit 70911fdc authored Aug 07, 2017 by Byungchul Park Committed by Ingo Molnar Aug 10, 2017

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.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-4-git-send-email-byungchul.park@lge.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 49347a98

kernel/locking/lockdep.c

+4 −3

Original line number	Original line	Diff line number	Diff line
	@@ -1881,7 +1881,7 @@ check_prev_add(struct task_struct curr, struct held_lock prev,
	if (entry->class == hlock_class(next)) {		if (entry->class == hlock_class(next)) {
	if (distance == 1)		if (distance == 1)
	entry->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));		print_lock_name(hlock_class(next));
	printk(KERN_CONT "\n");		printk(KERN_CONT "\n");
	dump_stack();		dump_stack();
	return graph_lock();		if (!graph_lock())
			return 0;
	}		}
	return 1;		return 2;
	}		}

	/*		/*