Add a test case shows that USED_IN_*_READ and ENABLE_*_READ can cause
deadlock too.
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
lib/locking-selftest.c | 55 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 17f8f6f37165..a899b3f0e2e5 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -1249,6 +1249,60 @@ GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_soft_rlock)
#include "locking-selftest-wlock.h"
GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion2_soft_wlock)
+#undef E1
+#undef E2
+#undef E3
+/*
+ * read-lock / write-lock recursion that is unsafe.
+ *
+ * A is a ENABLED_*_READ lock
+ * B is a USED_IN_*_READ lock
+ *
+ * read_lock(A);
+ * write_lock(B);
+ * <interrupt>
+ * read_lock(B);
+ * write_lock(A); // if this one is read_lock(), no deadlock
+ */
+
+#define E1() \
+ \
+ IRQ_DISABLE(); \
+ WL(B); \
+ LOCK(A); \
+ UNLOCK(A); \
+ WU(B); \
+ IRQ_ENABLE();
+
+#define E2() \
+ \
+ RL(A); \
+ RU(A); \
+
+#define E3() \
+ \
+ IRQ_ENTER(); \
+ RL(B); \
+ RU(B); \
+ IRQ_EXIT();
+
+/*
+ * Generate 24 testcases:
+ */
+#include "locking-selftest-hardirq.h"
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_hard_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_hard_wlock)
+
+#include "locking-selftest-softirq.h"
+#include "locking-selftest-rlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_soft_rlock)
+
+#include "locking-selftest-wlock.h"
+GENERATE_PERMUTATIONS_3_EVENTS(irq_read_recursion3_soft_wlock)
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define I_SPINLOCK(x) lockdep_reset_lock(&lock_##x.dep_map)
# define I_RWLOCK(x) lockdep_reset_lock(&rwlock_##x.dep_map)
@@ -2413,6 +2467,7 @@ void locking_selftest(void)
DO_TESTCASE_6x2x2RW("irq read-recursion", irq_read_recursion);
DO_TESTCASE_6x2x2RW("irq read-recursion #2", irq_read_recursion2);
+ DO_TESTCASE_6x2x2RW("irq read-recursion #3", irq_read_recursion3);
ww_tests();
--
2.28.0
