[PATCH] lockdep: better lock debugging

Generic lock debugging: - generalized lock debugging framework. For example, a bug in one lock subsystem turns off debugging in all lock subsystems. - got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from the mutex/rtmutex debugging code: it caused way too much prototype hackery, and lockdep will give the same information anyway. - ability to do silent tests - check lock freeing in vfree too. - more finegrained debugging options, to allow distributions to turn off more expensive debugging features. There's no separate 'held mutexes' list anymore - but there's a 'held locks' stack within lockdep, which unifies deadlock detection across all lock classes. (this is independent of the lockdep validation stuff - lockdep first checks whether we are holding a lock already) Here are the current debugging options: CONFIG_DEBUG_MUTEXES=y CONFIG_DEBUG_LOCK_ALLOC=y which do: config DEBUG_MUTEXES bool "Mutex debugging, basic checks" config DEBUG_LOCK_ALLOC bool "Detect incorrect freeing of live mutexes" Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Arjan van de Ven <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
k1132 · Jul 3, 2006 · 9a11b49 · 9a11b49
1 parent fb7e424
commit 9a11b49
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Showing 25 changed files with 265 additions and 567 deletions.
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
@@ -151,7 +151,7 @@ static struct sysrq_key_op sysrq_mountro_op = {
 static void sysrq_handle_showlocks(int key, struct pt_regs *pt_regs,
 				struct tty_struct *tty)
 {
-	mutex_debug_show_all_locks();
+	debug_show_all_locks();
 }
 static struct sysrq_key_op sysrq_showlocks_op = {
 	.handler	= sysrq_handle_showlocks,

diff --git a/include/asm-generic/mutex-null.h b/include/asm-generic/mutex-null.h
@@ -10,15 +10,10 @@
 #ifndef _ASM_GENERIC_MUTEX_NULL_H
 #define _ASM_GENERIC_MUTEX_NULL_H
 
-/* extra parameter only needed for mutex debugging: */
-#ifndef __IP__
-# define __IP__
-#endif
-
-#define __mutex_fastpath_lock(count, fail_fn)	      fail_fn(count __RET_IP__)
-#define __mutex_fastpath_lock_retval(count, fail_fn)  fail_fn(count __RET_IP__)
-#define __mutex_fastpath_unlock(count, fail_fn)       fail_fn(count __RET_IP__)
-#define __mutex_fastpath_trylock(count, fail_fn)      fail_fn(count)
-#define __mutex_slowpath_needs_to_unlock()	      1
+#define __mutex_fastpath_lock(count, fail_fn)		fail_fn(count)
+#define __mutex_fastpath_lock_retval(count, fail_fn)	fail_fn(count)
+#define __mutex_fastpath_unlock(count, fail_fn)		fail_fn(count)
+#define __mutex_fastpath_trylock(count, fail_fn)	fail_fn(count)
+#define __mutex_slowpath_needs_to_unlock()		1
 
 #endif
diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
@@ -0,0 +1,69 @@
+#ifndef __LINUX_DEBUG_LOCKING_H
+#define __LINUX_DEBUG_LOCKING_H
+
+extern int debug_locks;
+extern int debug_locks_silent;
+
+/*
+ * Generic 'turn off all lock debugging' function:
+ */
+extern int debug_locks_off(void);
+
+/*
+ * In the debug case we carry the caller's instruction pointer into
+ * other functions, but we dont want the function argument overhead
+ * in the nondebug case - hence these macros:
+ */
+#define _RET_IP_		(unsigned long)__builtin_return_address(0)
+#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
+
+#define DEBUG_LOCKS_WARN_ON(c)						\
+({									\
+	int __ret = 0;							\
+									\
+	if (unlikely(c)) {						\
+		if (debug_locks_off())					\
+			WARN_ON(1);					\
+		__ret = 1;						\
+	}								\
+	__ret;								\
+})
+
+#ifdef CONFIG_SMP
+# define SMP_DEBUG_LOCKS_WARN_ON(c)			DEBUG_LOCKS_WARN_ON(c)
+#else
+# define SMP_DEBUG_LOCKS_WARN_ON(c)			do { } while (0)
+#endif
+
+#ifdef CONFIG_DEBUG_LOCKING_API_SELFTESTS
+  extern void locking_selftest(void);
+#else
+# define locking_selftest()	do { } while (0)
+#endif
+
+#ifdef CONFIG_LOCKDEP
+extern void debug_show_all_locks(void);
+extern void debug_show_held_locks(struct task_struct *task);
+extern void debug_check_no_locks_freed(const void *from, unsigned long len);
+extern void debug_check_no_locks_held(struct task_struct *task);
+#else
+static inline void debug_show_all_locks(void)
+{
+}
+
+static inline void debug_show_held_locks(struct task_struct *task)
+{
+}
+
+static inline void
+debug_check_no_locks_freed(const void *from, unsigned long len)
+{
+}
+
+static inline void
+debug_check_no_locks_held(struct task_struct *task)
+{
+}
+#endif
+
+#endif
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
@@ -124,7 +124,6 @@ extern struct group_info init_groups;
 	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
 	.fs_excl	= ATOMIC_INIT(0),				\
 	.pi_lock	= SPIN_LOCK_UNLOCKED,				\
-	INIT_RT_MUTEXES(tsk)						\
 }
 
 

diff --git a/include/linux/mm.h b/include/linux/mm.h
@@ -14,6 +14,7 @@
 #include <linux/prio_tree.h>
 #include <linux/fs.h>
 #include <linux/mutex.h>
+#include <linux/debug_locks.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -1034,13 +1035,6 @@ static inline void vm_stat_account(struct mm_struct *mm,
 }
 #endif /* CONFIG_PROC_FS */
 
-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
 static inline void
 kernel_map_pages(struct page *page, int numpages, int enable)

diff --git a/include/linux/mutex-debug.h b/include/linux/mutex-debug.h
@@ -7,17 +7,11 @@
  * Mutexes - debugging helpers:
  */
 
-#define __DEBUG_MUTEX_INITIALIZER(lockname) \
-	, .held_list = LIST_HEAD_INIT(lockname.held_list), \
-	  .name = #lockname , .magic = &lockname
+#define __DEBUG_MUTEX_INITIALIZER(lockname)				\
+	, .magic = &lockname
 
-#define mutex_init(sem)		__mutex_init(sem, __FUNCTION__)
+#define mutex_init(sem)		__mutex_init(sem, __FILE__":"#sem)
 
 extern void FASTCALL(mutex_destroy(struct mutex *lock));
 
-extern void mutex_debug_show_all_locks(void);
-extern void mutex_debug_show_held_locks(struct task_struct *filter);
-extern void mutex_debug_check_no_locks_held(struct task_struct *task);
-extern void mutex_debug_check_no_locks_freed(const void *from, unsigned long len);
-
 #endif
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
@@ -50,8 +50,6 @@ struct mutex {
 	struct list_head	wait_list;
 #ifdef CONFIG_DEBUG_MUTEXES
 	struct thread_info	*owner;
-	struct list_head	held_list;
-	unsigned long		acquire_ip;
 	const char 		*name;
 	void			*magic;
 #endif
@@ -76,10 +74,6 @@ struct mutex_waiter {
 # define __DEBUG_MUTEX_INITIALIZER(lockname)
 # define mutex_init(mutex)			__mutex_init(mutex, NULL)
 # define mutex_destroy(mutex)				do { } while (0)
-# define mutex_debug_show_all_locks()			do { } while (0)
-# define mutex_debug_show_held_locks(p)			do { } while (0)
-# define mutex_debug_check_no_locks_held(task)		do { } while (0)
-# define mutex_debug_check_no_locks_freed(from, len)	do { } while (0)
 #endif
 
 #define __MUTEX_INITIALIZER(lockname) \

diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
@@ -29,8 +29,6 @@ struct rt_mutex {
 	struct task_struct	*owner;
 #ifdef CONFIG_DEBUG_RT_MUTEXES
 	int			save_state;
-	struct list_head	held_list_entry;
-	unsigned long		acquire_ip;
 	const char 		*name, *file;
 	int			line;
 	void			*magic;
@@ -98,14 +96,6 @@ extern int rt_mutex_trylock(struct rt_mutex *lock);
 
 extern void rt_mutex_unlock(struct rt_mutex *lock);
 
-#ifdef CONFIG_DEBUG_RT_MUTEXES
-# define INIT_RT_MUTEX_DEBUG(tsk)					\
-	.held_list_head	= LIST_HEAD_INIT(tsk.held_list_head),		\
-	.held_list_lock	= SPIN_LOCK_UNLOCKED
-#else
-# define INIT_RT_MUTEX_DEBUG(tsk)
-#endif
-
 #ifdef CONFIG_RT_MUTEXES
 # define INIT_RT_MUTEXES(tsk)						\
 	.pi_waiters	= PLIST_HEAD_INIT(tsk.pi_waiters, tsk.pi_lock),	\

diff --git a/include/linux/sched.h b/include/linux/sched.h
@@ -865,10 +865,6 @@ struct task_struct {
 	struct plist_head pi_waiters;
 	/* Deadlock detection and priority inheritance handling */
 	struct rt_mutex_waiter *pi_blocked_on;
-# ifdef CONFIG_DEBUG_RT_MUTEXES
-	spinlock_t held_list_lock;
-	struct list_head held_list_head;
-# endif
 #endif
 
 #ifdef CONFIG_DEBUG_MUTEXES

diff --git a/init/main.c b/init/main.c
@@ -47,6 +47,7 @@
 #include <linux/key.h>
 #include <linux/unwind.h>
 #include <linux/buffer_head.h>
+#include <linux/debug_locks.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -511,6 +512,13 @@ asmlinkage void __init start_kernel(void)
 	console_init();
 	if (panic_later)
 		panic(panic_later, panic_param);
+	/*
+	 * Need to run this when irqs are enabled, because it wants
+	 * to self-test [hard/soft]-irqs on/off lock inversion bugs
+	 * too:
+	 */
+	locking_selftest();
+
 #ifdef CONFIG_BLK_DEV_INITRD
 	if (initrd_start && !initrd_below_start_ok &&
 			initrd_start < min_low_pfn << PAGE_SHIFT) {

diff --git a/kernel/exit.c b/kernel/exit.c
@@ -933,10 +933,9 @@ fastcall NORET_TYPE void do_exit(long code)
 	if (unlikely(current->pi_state_cache))
 		kfree(current->pi_state_cache);
 	/*
-	 * If DEBUG_MUTEXES is on, make sure we are holding no locks:
+	 * Make sure we are holding no locks:
 	 */
-	mutex_debug_check_no_locks_held(tsk);
-	rt_mutex_debug_check_no_locks_held(tsk);
+	debug_check_no_locks_held(tsk);
 
 	if (tsk->io_context)
 		exit_io_context();

diff --git a/kernel/fork.c b/kernel/fork.c
@@ -919,10 +919,6 @@ static inline void rt_mutex_init_task(struct task_struct *p)
 	spin_lock_init(&p->pi_lock);
 	plist_head_init(&p->pi_waiters, &p->pi_lock);
 	p->pi_blocked_on = NULL;
-# ifdef CONFIG_DEBUG_RT_MUTEXES
-	spin_lock_init(&p->held_list_lock);
-	INIT_LIST_HEAD(&p->held_list_head);
-# endif
 #endif
 }
 

diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
@@ -20,52 +20,19 @@
 #include <linux/spinlock.h>
 #include <linux/kallsyms.h>
 #include <linux/interrupt.h>
+#include <linux/debug_locks.h>
 
 #include "mutex-debug.h"
 
-/*
- * We need a global lock when we walk through the multi-process
- * lock tree. Only used in the deadlock-debugging case.
- */
-DEFINE_SPINLOCK(debug_mutex_lock);
-
-/*
- * All locks held by all tasks, in a single global list:
- */
-LIST_HEAD(debug_mutex_held_locks);
-
-/*
- * In the debug case we carry the caller's instruction pointer into
- * other functions, but we dont want the function argument overhead
- * in the nondebug case - hence these macros:
- */
-#define __IP_DECL__		, unsigned long ip
-#define __IP__			, ip
-#define __RET_IP__		, (unsigned long)__builtin_return_address(0)
-
-/*
- * "mutex debugging enabled" flag. We turn it off when we detect
- * the first problem because we dont want to recurse back
- * into the tracing code when doing error printk or
- * executing a BUG():
- */
-int debug_mutex_on = 1;
-
 /*
  * Must be called with lock->wait_lock held.
  */
-void debug_mutex_set_owner(struct mutex *lock,
-			   struct thread_info *new_owner __IP_DECL__)
+void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
 {
 	lock->owner = new_owner;
-	DEBUG_LOCKS_WARN_ON(!list_empty(&lock->held_list));
-	if (debug_mutex_on) {
-		list_add_tail(&lock->held_list, &debug_mutex_held_locks);
-		lock->acquire_ip = ip;
-	}
 }
 
-void debug_mutex_init_waiter(struct mutex_waiter *waiter)
+void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
 {
 	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
 	waiter->magic = waiter;
@@ -87,9 +54,10 @@ void debug_mutex_free_waiter(struct mutex_waiter *waiter)
 }
 
 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
-			    struct thread_info *ti __IP_DECL__)
+			    struct thread_info *ti)
 {
 	SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
+
 	/* Mark the current thread as blocked on the lock: */
 	ti->task->blocked_on = waiter;
 	waiter->lock = lock;
@@ -109,24 +77,19 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
 
 void debug_mutex_unlock(struct mutex *lock)
 {
+	DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
 	DEBUG_LOCKS_WARN_ON(lock->magic != lock);
 	DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
 	DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
-	if (debug_mutex_on) {
-		DEBUG_LOCKS_WARN_ON(list_empty(&lock->held_list));
-		list_del_init(&lock->held_list);
-	}
 }
 
 void debug_mutex_init(struct mutex *lock, const char *name)
 {
 	/*
 	 * Make sure we are not reinitializing a held lock:
 	 */
-	mutex_debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 	lock->owner = NULL;
-	INIT_LIST_HEAD(&lock->held_list);
-	lock->name = name;
 	lock->magic = lock;
 }