[PATCH v2 5/8] locking: Add kselftests for ww_mutex ABBA deadlock detection

[Chris Wilson]

Signed-off-by: Chris Wilson 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Maarten Lankhorst 
Cc: Nicolai Hähnle 
---
 kernel/locking/test-ww_mutex.c | 98 ++
 1 file changed, 98 insertions(+)

diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index 835fa7a1036e..5a643ba2b020 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -153,6 +153,96 @@ static int test_aa(void)
return ret;
 }
 
+struct test_abba {
+   struct work_struct work;
+   struct ww_mutex a_mutex;
+   struct ww_mutex b_mutex;
+   struct completion a_ready;
+   struct completion b_ready;
+   bool resolve;
+   int result;
+};
+
+static void test_abba_work(struct work_struct *work)
+{
+   struct test_abba *abba = container_of(work, typeof(*abba), work);
+   struct ww_acquire_ctx ctx;
+   int err;
+
+   ww_acquire_init(, _class);
+   ww_mutex_lock(>b_mutex, );
+
+   complete(>b_ready);
+   wait_for_completion(>a_ready);
+
+   err = ww_mutex_lock(>a_mutex, );
+   if (abba->resolve && err == -EDEADLK) {
+   ww_mutex_unlock(>b_mutex);
+   ww_mutex_lock_slow(>a_mutex, );
+   err = ww_mutex_lock(>b_mutex, );
+   }
+
+   if (!err)
+   ww_mutex_unlock(>a_mutex);
+   ww_mutex_unlock(>b_mutex);
+   ww_acquire_fini();
+
+   abba->result = err;
+}
+
+static int test_abba(bool resolve)
+{
+   struct test_abba abba;
+   struct ww_acquire_ctx ctx;
+   int err, ret;
+
+   ww_mutex_init(_mutex, _class);
+   ww_mutex_init(_mutex, _class);
+   INIT_WORK_ONSTACK(, test_abba_work);
+   init_completion(_ready);
+   init_completion(_ready);
+   abba.resolve = resolve;
+
+   schedule_work();
+
+   ww_acquire_init(, _class);
+   ww_mutex_lock(_mutex, );
+
+   complete(_ready);
+   wait_for_completion(_ready);
+
+   err = ww_mutex_lock(_mutex, );
+   if (resolve && err == -EDEADLK) {
+   ww_mutex_unlock(_mutex);
+   ww_mutex_lock_slow(_mutex, );
+   err = ww_mutex_lock(_mutex, );
+   }
+
+   if (!err)
+   ww_mutex_unlock(_mutex);
+   ww_mutex_unlock(_mutex);
+   ww_acquire_fini();
+
+   flush_work();
+   destroy_work_on_stack();
+
+   ret = 0;
+   if (resolve) {
+   if (err || abba.result) {
+   pr_err("%s: failed to resolve ABBA deadlock, A err=%d, 
B err=%d\n",
+  __func__, err, abba.result);
+   ret = -EINVAL;
+   }
+   } else {
+   if (err != -EDEADLK && abba.result != -EDEADLK) {
+   pr_err("%s: missed ABBA deadlock, A err=%d, B err=%d\n",
+  __func__, err, abba.result);
+   ret = -EINVAL;
+   }
+   }
+   return ret;
+}
+
 static int __init test_ww_mutex_init(void)
 {
int ret;
@@ -165,6 +255,14 @@ static int __init test_ww_mutex_init(void)
if (ret)
return ret;
 
+   ret = test_abba(false);
+   if (ret)
+   return ret;
+
+   ret = test_abba(true);
+   if (ret)
+   return ret;
+
return 0;
 }
 
-- 
2.10.2

[PATCH v2 5/8] locking: Add kselftests for ww_mutex ABBA deadlock detection

[Chris Wilson]

Signed-off-by: Chris Wilson 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Maarten Lankhorst 
Cc: Nicolai Hähnle 
---
 kernel/locking/test-ww_mutex.c | 98 ++
 1 file changed, 98 insertions(+)

diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index 835fa7a1036e..5a643ba2b020 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -153,6 +153,96 @@ static int test_aa(void)
return ret;
 }
 
+struct test_abba {
+   struct work_struct work;
+   struct ww_mutex a_mutex;
+   struct ww_mutex b_mutex;
+   struct completion a_ready;
+   struct completion b_ready;
+   bool resolve;
+   int result;
+};
+
+static void test_abba_work(struct work_struct *work)
+{
+   struct test_abba *abba = container_of(work, typeof(*abba), work);
+   struct ww_acquire_ctx ctx;
+   int err;
+
+   ww_acquire_init(, _class);
+   ww_mutex_lock(>b_mutex, );
+
+   complete(>b_ready);
+   wait_for_completion(>a_ready);
+
+   err = ww_mutex_lock(>a_mutex, );
+   if (abba->resolve && err == -EDEADLK) {
+   ww_mutex_unlock(>b_mutex);
+   ww_mutex_lock_slow(>a_mutex, );
+   err = ww_mutex_lock(>b_mutex, );
+   }
+
+   if (!err)
+   ww_mutex_unlock(>a_mutex);
+   ww_mutex_unlock(>b_mutex);
+   ww_acquire_fini();
+
+   abba->result = err;
+}
+
+static int test_abba(bool resolve)
+{
+   struct test_abba abba;
+   struct ww_acquire_ctx ctx;
+   int err, ret;
+
+   ww_mutex_init(_mutex, _class);
+   ww_mutex_init(_mutex, _class);
+   INIT_WORK_ONSTACK(, test_abba_work);
+   init_completion(_ready);
+   init_completion(_ready);
+   abba.resolve = resolve;
+
+   schedule_work();
+
+   ww_acquire_init(, _class);
+   ww_mutex_lock(_mutex, );
+
+   complete(_ready);
+   wait_for_completion(_ready);
+
+   err = ww_mutex_lock(_mutex, );
+   if (resolve && err == -EDEADLK) {
+   ww_mutex_unlock(_mutex);
+   ww_mutex_lock_slow(_mutex, );
+   err = ww_mutex_lock(_mutex, );
+   }
+
+   if (!err)
+   ww_mutex_unlock(_mutex);
+   ww_mutex_unlock(_mutex);
+   ww_acquire_fini();
+
+   flush_work();
+   destroy_work_on_stack();
+
+   ret = 0;
+   if (resolve) {
+   if (err || abba.result) {
+   pr_err("%s: failed to resolve ABBA deadlock, A err=%d, 
B err=%d\n",
+  __func__, err, abba.result);
+   ret = -EINVAL;
+   }
+   } else {
+   if (err != -EDEADLK && abba.result != -EDEADLK) {
+   pr_err("%s: missed ABBA deadlock, A err=%d, B err=%d\n",
+  __func__, err, abba.result);
+   ret = -EINVAL;
+   }
+   }
+   return ret;
+}
+
 static int __init test_ww_mutex_init(void)
 {
int ret;
@@ -165,6 +255,14 @@ static int __init test_ww_mutex_init(void)
if (ret)
return ret;
 
+   ret = test_abba(false);
+   if (ret)
+   return ret;
+
+   ret = test_abba(true);
+   if (ret)
+   return ret;
+
return 0;
 }
 
-- 
2.10.2