[PATCH 2/4] locking: Add kselftests for ww_mutex AA deadlock detection

[Chris Wilson]

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Maarten Lankhorst <d...@mblankhorst.nl>
Cc: Nicolai Hähnle <nhaeh...@gmail.com>
---
 kernel/locking/test-ww_mutex.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index e94b807e06c2..02a4bacf8aac 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -118,6 +118,41 @@ static int test_mutex(void)
        return 0;
 }
 
+static int test_aa(void)
+{
+       struct ww_mutex mutex;
+       struct ww_acquire_ctx ctx;
+       int ret;
+
+       ww_mutex_init(&mutex, &ww_class);
+       ww_acquire_init(&ctx, &ww_class);
+
+       ww_mutex_lock(&mutex, &ctx);
+
+       if (ww_mutex_trylock(&mutex))  {
+               pr_err("%s: trylocked itself!\n", __func__);
+               ww_mutex_unlock(&mutex);
+               ret = -EINVAL;
+               goto out;
+       }
+
+       ret = ww_mutex_lock(&mutex, &ctx);
+       if (ret != -EALREADY) {
+               pr_err("%s: missed deadlock for recursing, ret=%d\n",
+                      __func__, ret);
+               if (!ret)
+                       ww_mutex_unlock(&mutex);
+               ret = -EINVAL;
+               goto out;
+       }
+
+       ret = 0;
+out:
+       ww_mutex_unlock(&mutex);
+       ww_acquire_fini(&ctx);
+       return ret;
+}
+
 static int __init test_ww_mutex_init(void)
 {
        int ret;
@@ -126,6 +161,10 @@ static int __init test_ww_mutex_init(void)
        if (ret)
                return ret;
 
+       ret = test_aa();
+       if (ret)
+               return ret;
+
        return 0;
 }
 
-- 
2.10.2