[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 <mingo@elte.hu>
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>

1 files changed, 15 insertions, 287 deletions

diff --git a/kernel/rtmutex-debug.c b/kernel/rtmutex-debug.c
index 4aa8a2c9f453..353a853bc390 100644
--- a/kernel/rtmutex-debug.c
+++ b/kernel/rtmutex-debug.c
@@ -26,6 +26,7 @@
 #include <linux/interrupt.h>
 #include <linux/plist.h>
 #include <linux/fs.h>
+#include <linux/debug_locks.h>
 
 #include "rtmutex_common.h"
 
@@ -45,8 +46,6 @@ do {								\
 		console_verbose();				\
 		if (spin_is_locked(&current->pi_lock))		\
 			spin_unlock(&current->pi_lock);		\
-		if (spin_is_locked(&current->held_list_lock))	\
-			spin_unlock(&current->held_list_lock);	\
 	}							\
 } while (0)
 
@@ -105,14 +104,6 @@ static void printk_task(task_t *p)
 		printk("<none>");
 }
 
-static void printk_task_short(task_t *p)
-{
-	if (p)
-		printk("%s/%d [%p, %3d]", p->comm, p->pid, p, p->prio);
-	else
-		printk("<none>");
-}
-
 static void printk_lock(struct rt_mutex *lock, int print_owner)
 {
 	if (lock->name)
@@ -128,222 +119,6 @@ static void printk_lock(struct rt_mutex *lock, int print_owner)
 		printk_task(rt_mutex_owner(lock));
 		printk("\n");
 	}
-	if (rt_mutex_owner(lock)) {
-		printk("... acquired at:               ");
-		print_symbol("%s\n", lock->acquire_ip);
-	}
-}
-
-static void printk_waiter(struct rt_mutex_waiter *w)
-{
-	printk("-------------------------\n");
-	printk("| waiter struct %p:\n", w);
-	printk("| w->list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
-	       w->list_entry.plist.prio_list.prev, w->list_entry.plist.prio_list.next,
-	       w->list_entry.plist.node_list.prev, w->list_entry.plist.node_list.next,
-	       w->list_entry.prio);
-	printk("| w->pi_list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
-	       w->pi_list_entry.plist.prio_list.prev, w->pi_list_entry.plist.prio_list.next,
-	       w->pi_list_entry.plist.node_list.prev, w->pi_list_entry.plist.node_list.next,
-	       w->pi_list_entry.prio);
-	printk("\n| lock:\n");
-	printk_lock(w->lock, 1);
-	printk("| w->ti->task:\n");
-	printk_task(w->task);
-	printk("| blocked at:  ");
-	print_symbol("%s\n", w->ip);
-	printk("-------------------------\n");
-}
-
-static void show_task_locks(task_t *p)
-{
-	switch (p->state) {
-	case TASK_RUNNING:		printk("R"); break;
-	case TASK_INTERRUPTIBLE:	printk("S"); break;
-	case TASK_UNINTERRUPTIBLE:	printk("D"); break;
-	case TASK_STOPPED:		printk("T"); break;
-	case EXIT_ZOMBIE:		printk("Z"); break;
-	case EXIT_DEAD:			printk("X"); break;
-	default:			printk("?"); break;
-	}
-	printk_task(p);
-	if (p->pi_blocked_on) {
-		struct rt_mutex *lock = p->pi_blocked_on->lock;
-
-		printk(" blocked on:");
-		printk_lock(lock, 1);
-	} else
-		printk(" (not blocked)\n");
-}
-
-void rt_mutex_show_held_locks(task_t *task, int verbose)
-{
-	struct list_head *curr, *cursor = NULL;
-	struct rt_mutex *lock;
-	task_t *t;
-	unsigned long flags;
-	int count = 0;
-
-	if (!rt_trace_on)
-		return;
-
-	if (verbose) {
-		printk("------------------------------\n");
-		printk("| showing all locks held by: |  (");
-		printk_task_short(task);
-		printk("):\n");
-		printk("------------------------------\n");
-	}
-
-next:
-	spin_lock_irqsave(&task->held_list_lock, flags);
-	list_for_each(curr, &task->held_list_head) {
-		if (cursor && curr != cursor)
-			continue;
-		lock = list_entry(curr, struct rt_mutex, held_list_entry);
-		t = rt_mutex_owner(lock);
-		WARN_ON(t != task);
-		count++;
-		cursor = curr->next;
-		spin_unlock_irqrestore(&task->held_list_lock, flags);
-
-		printk("\n#%03d:            ", count);
-		printk_lock(lock, 0);
-		goto next;
-	}
-	spin_unlock_irqrestore(&task->held_list_lock, flags);
-
-	printk("\n");
-}
-
-void rt_mutex_show_all_locks(void)
-{
-	task_t *g, *p;
-	int count = 10;
-	int unlock = 1;
-
-	printk("\n");
-	printk("----------------------\n");
-	printk("| showing all tasks: |\n");
-	printk("----------------------\n");
-
-	/*
-	 * Here we try to get the tasklist_lock as hard as possible,
-	 * if not successful after 2 seconds we ignore it (but keep
-	 * trying). This is to enable a debug printout even if a
-	 * tasklist_lock-holding task deadlocks or crashes.
-	 */
-retry:
-	if (!read_trylock(&tasklist_lock)) {
-		if (count == 10)
-			printk("hm, tasklist_lock locked, retrying... ");
-		if (count) {
-			count--;
-			printk(" #%d", 10-count);
-			mdelay(200);
-			goto retry;
-		}
-		printk(" ignoring it.\n");
-		unlock = 0;
-	}
-	if (count != 10)
-		printk(" locked it.\n");
-
-	do_each_thread(g, p) {
-		show_task_locks(p);
-		if (!unlock)
-			if (read_trylock(&tasklist_lock))
-				unlock = 1;
-	} while_each_thread(g, p);
-
-	printk("\n");
-
-	printk("-----------------------------------------\n");
-	printk("| showing all locks held in the system: |\n");
-	printk("-----------------------------------------\n");
-
-	do_each_thread(g, p) {
-		rt_mutex_show_held_locks(p, 0);
-		if (!unlock)
-			if (read_trylock(&tasklist_lock))
-				unlock = 1;
-	} while_each_thread(g, p);
-
-
-	printk("=============================================\n\n");
-
-	if (unlock)
-		read_unlock(&tasklist_lock);
-}
-
-void rt_mutex_debug_check_no_locks_held(task_t *task)
-{
-	struct rt_mutex_waiter *w;
-	struct list_head *curr;
-	struct rt_mutex *lock;
-
-	if (!rt_trace_on)
-		return;
-	if (!rt_prio(task->normal_prio) && rt_prio(task->prio)) {
-		printk("BUG: PI priority boost leaked!\n");
-		printk_task(task);
-		printk("\n");
-	}
-	if (list_empty(&task->held_list_head))
-		return;
-
-	spin_lock(&task->pi_lock);
-	plist_for_each_entry(w, &task->pi_waiters, pi_list_entry) {
-		TRACE_OFF();
-
-		printk("hm, PI interest held at exit time? Task:\n");
-		printk_task(task);
-		printk_waiter(w);
-		return;
-	}
-	spin_unlock(&task->pi_lock);
-
-	list_for_each(curr, &task->held_list_head) {
-		lock = list_entry(curr, struct rt_mutex, held_list_entry);
-
-		printk("BUG: %s/%d, lock held at task exit time!\n",
-		       task->comm, task->pid);
-		printk_lock(lock, 1);
-		if (rt_mutex_owner(lock) != task)
-			printk("exiting task is not even the owner??\n");
-	}
-}
-
-int rt_mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
-{
-	const void *to = from + len;
-	struct list_head *curr;
-	struct rt_mutex *lock;
-	unsigned long flags;
-	void *lock_addr;
-
-	if (!rt_trace_on)
-		return 0;
-
-	spin_lock_irqsave(&current->held_list_lock, flags);
-	list_for_each(curr, &current->held_list_head) {
-		lock = list_entry(curr, struct rt_mutex, held_list_entry);
-		lock_addr = lock;
-		if (lock_addr < from || lock_addr >= to)
-			continue;
-		TRACE_OFF();
-
-		printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
-			current->comm, current->pid, lock, from, to);
-		dump_stack();
-		printk_lock(lock, 1);
-		if (rt_mutex_owner(lock) != current)
-			printk("freeing task is not even the owner??\n");
-		return 1;
-	}
-	spin_unlock_irqrestore(&current->held_list_lock, flags);
-
-	return 0;
 }
 
 void rt_mutex_debug_task_free(struct task_struct *task)
@@ -395,85 +170,41 @@ void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
 	       current->comm, current->pid);
 	printk_lock(waiter->lock, 1);
 
-	printk("... trying at:                 ");
-	print_symbol("%s\n", waiter->ip);
-
 	printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
 	printk_lock(waiter->deadlock_lock, 1);
 
-	rt_mutex_show_held_locks(current, 1);
-	rt_mutex_show_held_locks(task, 1);
+	debug_show_held_locks(current);
+	debug_show_held_locks(task);
 
 	printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
 	show_stack(task, NULL);
 	printk("\n%s/%d's [current] stackdump:\n\n",
 	       current->comm, current->pid);
 	dump_stack();
-	rt_mutex_show_all_locks();
+	debug_show_all_locks();
+
 	printk("[ turning off deadlock detection."
 	       "Please report this trace. ]\n\n");
 	local_irq_disable();
 }
 
-void debug_rt_mutex_lock(struct rt_mutex *lock __IP_DECL__)
+void debug_rt_mutex_lock(struct rt_mutex *lock)
 {
-	unsigned long flags;
-
-	if (rt_trace_on) {
-		TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
-
-		spin_lock_irqsave(&current->held_list_lock, flags);
-		list_add_tail(&lock->held_list_entry, &current->held_list_head);
-		spin_unlock_irqrestore(&current->held_list_lock, flags);
-
-		lock->acquire_ip = ip;
-	}
 }
 
 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 {
-	unsigned long flags;
-
-	if (rt_trace_on) {
-		TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
-		TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
-
-		spin_lock_irqsave(&current->held_list_lock, flags);
-		list_del_init(&lock->held_list_entry);
-		spin_unlock_irqrestore(&current->held_list_lock, flags);
-	}
+	TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
 }
 
-void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
-			       struct task_struct *powner __IP_DECL__)
+void
+debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 {
-	unsigned long flags;
-
-	if (rt_trace_on) {
-		TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
-
-		spin_lock_irqsave(&powner->held_list_lock, flags);
-		list_add_tail(&lock->held_list_entry, &powner->held_list_head);
-		spin_unlock_irqrestore(&powner->held_list_lock, flags);
-
-		lock->acquire_ip = ip;
-	}
 }
 
 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 {
-	unsigned long flags;
-
-	if (rt_trace_on) {
-		struct task_struct *owner = rt_mutex_owner(lock);
-
-		TRACE_WARN_ON_LOCKED(!owner);
-		TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
-
-		spin_lock_irqsave(&owner->held_list_lock, flags);
-		list_del_init(&lock->held_list_entry);
-		spin_unlock_irqrestore(&owner->held_list_lock, flags);
-	}
+	TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
 }
 
 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
@@ -493,14 +224,11 @@ void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
 
 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
 {
-	void *addr = lock;
-
-	if (rt_trace_on) {
-		rt_mutex_debug_check_no_locks_freed(addr,
-						    sizeof(struct rt_mutex));
-		INIT_LIST_HEAD(&lock->held_list_entry);
-		lock->name = name;
-	}
+	/*
+	 * Make sure we are not reinitializing a held lock:
+	 */
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+	lock->name = name;
 }
 
 void rt_mutex_deadlock_account_lock(struct rt_mutex *lock, task_t *task)