linux-kernel - [tip: locking/core] locking/lockdep: Add a test for lockdep_set

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Message-ID: <172963403231.1442.6610755531326274395.tip-bot2@tip-bot2>
Date: Tue, 22 Oct 2024 21:53:52 -0000
From: "tip-bot2 for Ahmed Ehab" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ahmed Ehab <bottaawesome633@...il.com>, Boqun Feng <boqun.feng@...il.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: locking/core] locking/lockdep: Add a test for lockdep_set_subclass()

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     5eadeb7b3bc206e2ac9494e9499e7c1f1e44eab7
Gitweb:        https://git.kernel.org/tip/5eadeb7b3bc206e2ac9494e9499e7c1f1e44eab7
Author:        Ahmed Ehab <bottaawesome633@...il.com>
AuthorDate:    Thu, 05 Sep 2024 04:12:20 +03:00
Committer:     Boqun Feng <boqun.feng@...il.com>
CommitterDate: Thu, 17 Oct 2024 21:21:16 -07:00

locking/lockdep: Add a test for lockdep_set_subclass()

Add a test case to ensure that no new name string literal will be
created in lockdep_set_subclass(), otherwise a warning will be triggered
in look_up_lock_class(). Add this to catch the problem in the future.

[boqun: Reword the title, replace #if with #ifdef and rename functions
and variables]

Signed-off-by: Ahmed Ehab <bottaawesome633@...il.com>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
Link: https://lore.kernel.org/lkml/20240905011220.356973-1-bottaawesome633@gmail.com/
---
 lib/locking-selftest.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 6f6a5fc..6e0c019 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -2710,6 +2710,43 @@ static void local_lock_3B(void)
 
 }
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static inline const char *rw_semaphore_lockdep_name(struct rw_semaphore *rwsem)
+{
+	return rwsem->dep_map.name;
+}
+#else
+static inline const char *rw_semaphore_lockdep_name(struct rw_semaphore *rwsem)
+{
+	return NULL;
+}
+#endif
+
+static void test_lockdep_set_subclass_name(void)
+{
+	const char *name_before = rw_semaphore_lockdep_name(&rwsem_X1);
+	const char *name_after;
+
+	lockdep_set_subclass(&rwsem_X1, 1);
+	name_after = rw_semaphore_lockdep_name(&rwsem_X1);
+	DEBUG_LOCKS_WARN_ON(name_before != name_after);
+}
+
+/*
+ * lockdep_set_subclass() should reuse the existing lock class name instead
+ * of creating a new one.
+ */
+static void lockdep_set_subclass_name_test(void)
+{
+	printk("  --------------------------------------------------------------------------\n");
+	printk("  | lockdep_set_subclass() name test|\n");
+	printk("  -----------------------------------\n");
+
+	print_testname("compare name before and after");
+	dotest(test_lockdep_set_subclass_name, SUCCESS, LOCKTYPE_RWSEM);
+	pr_cont("\n");
+}
+
 static void local_lock_tests(void)
 {
 	printk("  --------------------------------------------------------------------------\n");
@@ -2920,6 +2957,8 @@ void locking_selftest(void)
 	dotest(hardirq_deadlock_softirq_not_deadlock, FAILURE, LOCKTYPE_SPECIAL);
 	pr_cont("\n");
 
+	lockdep_set_subclass_name_test();
+
 	if (unexpected_testcase_failures) {
 		printk("-----------------------------------------------------------------\n");
 		debug_locks = 0;