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Commit 9a11b49a authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent fb7e4241

drivers/char/sysrq.c

+1 −1
Original line number Diff line number Diff line
@@ -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,

include/asm-generic/mutex-null.h

+5 −10
Original line number Diff line number Diff line
@@ -10,14 +10,9 @@ 
#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_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

include/linux/debug_locks.h

0 → 100644
+69 −0
Original line number Diff line number Diff line 
#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

include/linux/init_task.h

+0 −1
Original line number Diff line number Diff line
@@ -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)						\

}

include/linux/mm.h

+1 −7
Original line number Diff line number Diff line
@@ -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)