1 files changed, 99 insertions, 0 deletions
diff --git a/include/linux/hung_task.h b/include/linux/hung_task.h
new file mode 100644
index 000000000000..1bc2b3244613
--- /dev/null
+++ b/include/linux/hung_task.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Detect Hung Task: detecting tasks stuck in D state
+ *
+ * Copyright (C) 2025 Tongcheng Travel (www.ly.com)
+ * Author: Lance Yang <mingzhe.yang@ly.com>
+ */
+#ifndef __LINUX_HUNG_TASK_H
+#define __LINUX_HUNG_TASK_H
+
+#include <linux/bug.h>
+#include <linux/sched.h>
+#include <linux/compiler.h>
+
+/*
+ * @blocker: Combines lock address and blocking type.
+ *
+ * Since lock pointers are at least 4-byte aligned(32-bit) or 8-byte
+ * aligned(64-bit). This leaves the 2 least bits (LSBs) of the pointer
+ * always zero. So we can use these bits to encode the specific blocking
+ * type.
+ *
+ * Type encoding:
+ * 00 - Blocked on mutex        (BLOCKER_TYPE_MUTEX)
+ * 01 - Blocked on semaphore    (BLOCKER_TYPE_SEM)
+ * 10 - Blocked on rt-mutex     (BLOCKER_TYPE_RTMUTEX)
+ * 11 - Blocked on rw-semaphore (BLOCKER_TYPE_RWSEM)
+ */
+#define BLOCKER_TYPE_MUTEX      0x00UL
+#define BLOCKER_TYPE_SEM        0x01UL
+#define BLOCKER_TYPE_RTMUTEX    0x02UL
+#define BLOCKER_TYPE_RWSEM      0x03UL
+
+#define BLOCKER_TYPE_MASK       0x03UL
+
+#ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER
+static inline void hung_task_set_blocker(void *lock, unsigned long type)
+{
+	unsigned long lock_ptr = (unsigned long)lock;
+
+	WARN_ON_ONCE(!lock_ptr);
+	WARN_ON_ONCE(READ_ONCE(current->blocker));
+
+	/*
+	 * If the lock pointer matches the BLOCKER_TYPE_MASK, return
+	 * without writing anything.
+	 */
+	if (WARN_ON_ONCE(lock_ptr & BLOCKER_TYPE_MASK))
+		return;
+
+	WRITE_ONCE(current->blocker, lock_ptr | type);
+}
+
+static inline void hung_task_clear_blocker(void)
+{
+	WARN_ON_ONCE(!READ_ONCE(current->blocker));
+
+	WRITE_ONCE(current->blocker, 0UL);
+}
+
+/*
+ * hung_task_get_blocker_type - Extracts blocker type from encoded blocker
+ * address.
+ *
+ * @blocker: Blocker pointer with encoded type (via LSB bits)
+ *
+ * Returns: BLOCKER_TYPE_MUTEX, BLOCKER_TYPE_SEM, etc.
+ */
+static inline unsigned long hung_task_get_blocker_type(unsigned long blocker)
+{
+	WARN_ON_ONCE(!blocker);
+
+	return blocker & BLOCKER_TYPE_MASK;
+}
+
+static inline void *hung_task_blocker_to_lock(unsigned long blocker)
+{
+	WARN_ON_ONCE(!blocker);
+
+	return (void *)(blocker & ~BLOCKER_TYPE_MASK);
+}
+#else
+static inline void hung_task_set_blocker(void *lock, unsigned long type)
+{
+}
+static inline void hung_task_clear_blocker(void)
+{
+}
+static inline unsigned long hung_task_get_blocker_type(unsigned long blocker)
+{
+	return 0UL;
+}
+static inline void *hung_task_blocker_to_lock(unsigned long blocker)
+{
+	return NULL;
+}
+#endif
+
+#endif /* __LINUX_HUNG_TASK_H */