linux-kernel - [PATCH] lockdep/selftest: Add tests for the mixed read-write case.

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Message-ID: <5151C94B.7000407@canonical.com>
Date:	Tue, 26 Mar 2013 17:14:03 +0100
From:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
To:	LKML <linux-kernel@...r.kernel.org>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Subject: [PATCH] lockdep/selftest: Add tests for the mixed read-write case.

rlock_AA5 will pass unexpectedly, marking the test as FAILED and breaking lockdep for everyone.

The following test should make lockdep complain, but currently doesn't:

lock(a); readlock(x);

writelock(x); lock(a);

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@...onical.com>
---

diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 8a1a230..d0d2540 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -301,6 +301,51 @@ static void rsem_AA3(void)
 	RSL(X2); // this one should fail
 }
 
+static void rlock_AA4(void)
+{
+	ML(A);
+	RL(X1);
+	RU(X1);
+	MU(A);
+
+	RL(X1);
+	ML(A);
+}
+
+static void rsem_AA4(void)
+{
+	ML(A);
+	RSL(X1);
+	RSU(X1);
+	MU(A);
+
+	RSL(X1);
+	ML(A);
+}
+
+static void rlock_AA5(void)
+{
+	ML(A);
+	RL(X1);
+	RU(X1);
+	MU(A);
+
+	WL(X1);
+	ML(A);
+}
+
+static void rsem_AA5(void)
+{
+	ML(A);
+	RSL(X1);
+	RSU(X1);
+	MU(A);
+
+	WSL(X1);
+	ML(A);
+}
+
+
 /*
  * ABBA deadlock:
  */
@@ -1661,6 +1706,21 @@ void locking_selftest(void)
 	dotest(rsem_AA3, FAILURE, LOCKTYPE_RWSEM);
 	printk("\n");
 
+	print_testname("mixed normal-read-lock");
+	printk("             |");
+	dotest(rlock_AA4, SUCCESS, LOCKTYPE_RWLOCK);
+	printk("             |");
+	dotest(rsem_AA4, FAILURE, LOCKTYPE_RWSEM);
+	printk("\n");
+
+	print_testname("mixed normal-r/w-lock");
+	printk("             |");
+	dotest(rlock_AA5, FAILURE, LOCKTYPE_RWLOCK);
+	printk("             |");
+	dotest(rsem_AA5, FAILURE, LOCKTYPE_RWSEM);
+	printk("\n");
+
+
 	printk("  --------------------------------------------------------------------------\n");
 
 	/*

--
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