[PATCH] pi-futex: rt mutex debug

Runtime debugging functionality for rt-mutexes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/mm.h

@@ -1034,6 +1034,7 @@ static inline void
 debug_check_no_locks_freed(const void *from, unsigned long len)
 {
 	mutex_debug_check_no_locks_freed(from, len);
+	rt_mutex_debug_check_no_locks_freed(from, len);
 }
 
 #ifndef CONFIG_DEBUG_PAGEALLOC

include/linux/rtmutex.h

@@ -40,6 +40,19 @@ struct rt_mutex {
 struct rt_mutex_waiter;
 struct hrtimer_sleeper;
 
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+ extern int rt_mutex_debug_check_no_locks_freed(const void *from,
+						unsigned long len);
+ extern void rt_mutex_debug_check_no_locks_held(struct task_struct *task);
+#else
+ static inline int rt_mutex_debug_check_no_locks_freed(const void *from,
+						       unsigned long len)
+ {
+	return 0;
+ }
+# define rt_mutex_debug_check_no_locks_held(task)	do { } while (0)
+#endif
+
 #ifdef CONFIG_DEBUG_RT_MUTEXES
 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
 	, .name = #mutexname, .file = __FILE__, .line = __LINE__

kernel/Makefile

@@ -17,6 +17,7 @@ ifeq ($(CONFIG_COMPAT),y)
 obj-$(CONFIG_FUTEX) += futex_compat.o
 endif
 obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
+obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
 obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
 obj-$(CONFIG_SMP) += cpu.o spinlock.o
 obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o

kernel/exit.c

@@ -929,6 +929,7 @@ fastcall NORET_TYPE void do_exit(long code)
 	 * If DEBUG_MUTEXES is on, make sure we are holding no locks:
 	 */
 	mutex_debug_check_no_locks_held(tsk);
+	rt_mutex_debug_check_no_locks_held(tsk);
 
 	if (tsk->io_context)
 		exit_io_context();

kernel/rtmutex-debug.h

+/*
+ * RT-Mutexes: blocking mutual exclusion locks with PI support
+ *
+ * started by Ingo Molnar and Thomas Gleixner:
+ *
+ *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
+ *
+ * This file contains macros used solely by rtmutex.c. Debug version.
+ */
+
+#define __IP_DECL__		, unsigned long ip
+#define __IP__			, ip
+#define __RET_IP__		, (unsigned long)__builtin_return_address(0)
+
+extern void
+rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task);
+extern void rt_mutex_deadlock_account_unlock(struct task_struct *task);
+extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
+extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
+extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);
+extern void debug_rt_mutex_lock(struct rt_mutex *lock __IP_DECL__);
+extern void debug_rt_mutex_unlock(struct rt_mutex *lock);
+extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
+				      struct task_struct *powner __IP_DECL__);
+extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock);
+extern void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *waiter,
+				    struct rt_mutex *lock);
+extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter);
+# define debug_rt_mutex_reset_waiter(w)			\
+	do { (w)->deadlock_lock = NULL; } while (0)
+
+static inline int debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
+						 int detect)
+{
+	return (waiter != NULL);
+}

lib/Kconfig.debug

@@ -107,6 +107,19 @@ config DEBUG_MUTEXES
 	 This allows mutex semantics violations and mutex related deadlocks
 	 (lockups) to be detected and reported automatically.
 
+config DEBUG_RT_MUTEXES
+	bool "RT Mutex debugging, deadlock detection"
+	default y
+	depends on DEBUG_KERNEL && RT_MUTEXES
+	help
+	 This allows rt mutex semantics violations and rt mutex related
+	 deadlocks (lockups) to be detected and reported automatically.
+
+config DEBUG_PI_LIST
+	bool
+	default y
+	depends on DEBUG_RT_MUTEXES
+
 config DEBUG_SPINLOCK
 	bool "Spinlock debugging"
 	depends on DEBUG_KERNEL

mm/slab.c

@@ -107,6 +107,7 @@
 #include	<linux/nodemask.h>
 #include	<linux/mempolicy.h>
 #include	<linux/mutex.h>
+#include	<linux/rtmutex.h>
 
 #include	<asm/uaccess.h>
 #include	<asm/cacheflush.h>