linux-kernel - [PATCH v3 28/30] locking/lockdep: Adjust selftest case for recursive read lock

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Date:   Fri, 28 Jun 2019 17:15:26 +0800
From:   Yuyang Du <duyuyang@...il.com>
To:     peterz@...radead.org, will.deacon@....com, mingo@...nel.org
Cc:     bvanassche@....org, ming.lei@...hat.com, frederic@...nel.org,
        tglx@...utronix.de, linux-kernel@...r.kernel.org,
        longman@...hat.com, paulmck@...ux.vnet.ibm.com,
        boqun.feng@...il.com, Yuyang Du <duyuyang@...il.com>
Subject: [PATCH v3 28/30] locking/lockdep: Adjust selftest case for recursive read lock

Now that we support recursive read locks, a previously failed case:

 ----------------------------------------------------------------------------
                                  | spin |wlock |rlock |mutex | wsem | rsem |
   --------------------------------------------------------------------------
   mixed read-lock/lock-write ABBA:             |FAILED|             |  ok  |

can be added back. Now we have:

	Good, all 262 testcases passed!

See the case in: e91498589746065e3a ("Add mixed read-write ABBA tests")

It is worth noting that previously for the lock inversion deadlock checks,
the SUCCESS's of _rlock cases are only because the dependencies having
recursive-read locks (rlock) are not included in the graph.

Signed-off-by: Yuyang Du <duyuyang@...il.com>
---
 lib/locking-selftest.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index a170554..7d14d87 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -462,12 +462,13 @@ static void rwsem_ABBA3(void)
 
 /*
  * ABBA deadlock:
+ *
+ * Should fail except for either A or B is rlock.
  */
-
 #define E()					\
 						\
 	LOCK_UNLOCK_2(A, B);			\
-	LOCK_UNLOCK_2(B, A); /* fail */
+	LOCK_UNLOCK_2(B, A);
 
 /*
  * 6 testcases:
@@ -494,13 +495,15 @@ static void rwsem_ABBA3(void)
 
 /*
  * AB BC CA deadlock:
+ *
+ * Should fail except for rlock.
  */
 
 #define E()					\
 						\
 	LOCK_UNLOCK_2(A, B);			\
 	LOCK_UNLOCK_2(B, C);			\
-	LOCK_UNLOCK_2(C, A); /* fail */
+	LOCK_UNLOCK_2(C, A);
 
 /*
  * 6 testcases:
@@ -527,13 +530,15 @@ static void rwsem_ABBA3(void)
 
 /*
  * AB CA BC deadlock:
+ *
+ * Should fail except for rlock.
  */
 
 #define E()					\
 						\
 	LOCK_UNLOCK_2(A, B);			\
 	LOCK_UNLOCK_2(C, A);			\
-	LOCK_UNLOCK_2(B, C); /* fail */
+	LOCK_UNLOCK_2(B, C);
 
 /*
  * 6 testcases:
@@ -560,6 +565,8 @@ static void rwsem_ABBA3(void)
 
 /*
  * AB BC CD DA deadlock:
+ *
+ * Should fail except for rlock.
  */
 
 #define E()					\
@@ -567,7 +574,7 @@ static void rwsem_ABBA3(void)
 	LOCK_UNLOCK_2(A, B);			\
 	LOCK_UNLOCK_2(B, C);			\
 	LOCK_UNLOCK_2(C, D);			\
-	LOCK_UNLOCK_2(D, A); /* fail */
+	LOCK_UNLOCK_2(D, A);
 
 /*
  * 6 testcases:
@@ -594,13 +601,15 @@ static void rwsem_ABBA3(void)
 
 /*
  * AB CD BD DA deadlock:
+ *
+ * Should fail except for rlock.
  */
 #define E()					\
 						\
 	LOCK_UNLOCK_2(A, B);			\
 	LOCK_UNLOCK_2(C, D);			\
 	LOCK_UNLOCK_2(B, D);			\
-	LOCK_UNLOCK_2(D, A); /* fail */
+	LOCK_UNLOCK_2(D, A);
 
 /*
  * 6 testcases:
@@ -627,13 +636,15 @@ static void rwsem_ABBA3(void)
 
 /*
  * AB CD BC DA deadlock:
+ *
+ * Should fail except for rlock.
  */
 #define E()					\
 						\
 	LOCK_UNLOCK_2(A, B);			\
 	LOCK_UNLOCK_2(C, D);			\
 	LOCK_UNLOCK_2(B, C);			\
-	LOCK_UNLOCK_2(D, A); /* fail */
+	LOCK_UNLOCK_2(D, A);
 
 /*
  * 6 testcases:
@@ -2033,13 +2044,6 @@ void locking_selftest(void)
 	print_testname("mixed read-lock/lock-write ABBA");
 	pr_cont("             |");
 	dotest(rlock_ABBA1, FAILURE, LOCKTYPE_RWLOCK);
-#ifdef CONFIG_PROVE_LOCKING
-	/*
-	 * Lockdep does indeed fail here, but there's nothing we can do about
-	 * that now.  Don't kill lockdep for it.
-	 */
-	unexpected_testcase_failures--;
-#endif
 
 	pr_cont("             |");
 	dotest(rwsem_ABBA1, FAILURE, LOCKTYPE_RWSEM);
-- 
1.8.3.1