[PATCH] lockdep: remove mutex deadlock checking code

With the lock validator we detect mutex deadlocks (and more), the mutex
deadlock checking code is both redundant and slower.  So remove it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 316 deletions

diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
index fe0e9f2714d3..a92de145ed0d 100644
--- a/kernel/mutex-debug.c
+++ b/kernel/mutex-debug.c
@@ -51,321 +51,6 @@ LIST_HEAD(debug_mutex_held_locks);
  */
 int debug_mutex_on = 1;
 
-static void printk_task(struct task_struct *p)
-{
-        if (p)
-                printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
-        else
-                printk("<none>");
-}
-
-static void printk_ti(struct thread_info *ti)
-{
-        if (ti)
-                printk_task(ti->task);
-        else
-                printk("<none>");
-}
-
-static void printk_task_short(struct task_struct *p)
-{
-        if (p)
-                printk("%s/%d [%p, %3d]", p->comm, p->pid, p, p->prio);
-        else
-                printk("<none>");
-}
-
-static void printk_lock(struct mutex *lock, int print_owner)
-{
-        printk(" [%p] {%s}\n", lock, lock->name);
-
-        if (print_owner && lock->owner) {
-                printk(".. held by:  ");
-                printk_ti(lock->owner);
-                printk("\n");
-        }
-        if (lock->owner) {
-                printk("... acquired at:               ");
-                print_symbol("%s\n", lock->acquire_ip);
-        }
-}
-
-/*
- * printk locks held by a task:
- */
-static void show_task_locks(struct task_struct *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->blocked_on) {
-                struct mutex *lock = p->blocked_on->lock;
-
-                printk(" blocked on mutex:");
-                printk_lock(lock, 1);
-        } else
-                printk(" (not blocked on mutex)\n");
-}
-
-/*
- * printk all locks held in the system (if filter == NULL),
- * or all locks belonging to a single task (if filter != NULL):
- */
-void show_held_locks(struct task_struct *filter)
-{
-        struct list_head *curr, *cursor = NULL;
-        struct mutex *lock;
-        struct thread_info *t;
-        unsigned long flags;
-        int count = 0;
-
-        if (filter) {
-                printk("------------------------------\n");
-                printk("| showing all locks held by: |  (");
-                printk_task_short(filter);
-                printk("):\n");
-                printk("------------------------------\n");
-        } else {
-                printk("---------------------------\n");
-                printk("| showing all locks held: |\n");
-                printk("---------------------------\n");
-        }
-
-        /*
-         * Play safe and acquire the global trace lock. We
-         * cannot printk with that lock held so we iterate
-         * very carefully:
-         */
-next:
-        debug_spin_lock_save(&debug_mutex_lock, flags);
-        list_for_each(curr, &debug_mutex_held_locks) {
-                if (cursor && curr != cursor)
-                        continue;
-                lock = list_entry(curr, struct mutex, held_list);
-                t = lock->owner;
-                if (filter && (t != filter->thread_info))
-                        continue;
-                count++;
-                cursor = curr->next;
-                debug_spin_unlock_restore(&debug_mutex_lock, flags);
-
-                printk("\n#%03d:            ", count);
-                printk_lock(lock, filter ? 0 : 1);
-                goto next;
-        }
-        debug_spin_unlock_restore(&debug_mutex_lock, flags);
-        printk("\n");
-}
-
-void mutex_debug_show_all_locks(void)
-{
-        struct task_struct *g, *p;
-        int count = 10;
-        int unlock = 1;
-
-        printk("\nShowing all blocking locks in the system:\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");
-        show_held_locks(NULL);
-        printk("=============================================\n\n");
-
-        if (unlock)
-                read_unlock(&tasklist_lock);
-}
-
-static void report_deadlock(struct task_struct *task, struct mutex *lock,
-                            struct mutex *lockblk, unsigned long ip)
-{
-        printk("\n%s/%d is trying to acquire this lock:\n",
-                current->comm, current->pid);
-        printk_lock(lock, 1);
-        printk("... trying at:                 ");
-        print_symbol("%s\n", ip);
-        show_held_locks(current);
-
-        if (lockblk) {
-                printk("but %s/%d is deadlocking current task %s/%d!\n\n",
-                        task->comm, task->pid, current->comm, current->pid);
-                printk("\n%s/%d is blocked on this lock:\n",
-                        task->comm, task->pid);
-                printk_lock(lockblk, 1);
-
-                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();
-        mutex_debug_show_all_locks();
-        printk("[ turning off deadlock detection. Please report this. ]\n\n");
-        local_irq_disable();
-}
-
-/*
- * Recursively check for mutex deadlocks:
- */
-static int check_deadlock(struct mutex *lock, int depth,
-                          struct thread_info *ti, unsigned long ip)
-{
-        struct mutex *lockblk;
-        struct task_struct *task;
-
-        if (!debug_mutex_on)
-                return 0;
-
-        ti = lock->owner;
-        if (!ti)
-                return 0;
-
-        task = ti->task;
-        lockblk = NULL;
-        if (task->blocked_on)
-                lockblk = task->blocked_on->lock;
-
-        /* Self-deadlock: */
-        if (current == task) {
-                DEBUG_OFF();
-                if (depth)
-                        return 1;
-                printk("\n==========================================\n");
-                printk(  "[ BUG: lock recursion deadlock detected! |\n");
-                printk(  "------------------------------------------\n");
-                report_deadlock(task, lock, NULL, ip);
-                return 0;
-        }
-
-        /* Ugh, something corrupted the lock data structure? */
-        if (depth > 20) {
-                DEBUG_OFF();
-                printk("\n===========================================\n");
-                printk(  "[ BUG: infinite lock dependency detected!? |\n");
-                printk(  "-------------------------------------------\n");
-                report_deadlock(task, lock, lockblk, ip);
-                return 0;
-        }
-
-        /* Recursively check for dependencies: */
-        if (lockblk && check_deadlock(lockblk, depth+1, ti, ip)) {
-                printk("\n============================================\n");
-                printk(  "[ BUG: circular locking deadlock detected! ]\n");
-                printk(  "--------------------------------------------\n");
-                report_deadlock(task, lock, lockblk, ip);
-                return 0;
-        }
-        return 0;
-}
-
-/*
- * Called when a task exits, this function checks whether the
- * task is holding any locks, and reports the first one if so:
- */
-void mutex_debug_check_no_locks_held(struct task_struct *task)
-{
-        struct list_head *curr, *next;
-        struct thread_info *t;
-        unsigned long flags;
-        struct mutex *lock;
-
-        if (!debug_mutex_on)
-                return;
-
-        debug_spin_lock_save(&debug_mutex_lock, flags);
-        list_for_each_safe(curr, next, &debug_mutex_held_locks) {
-                lock = list_entry(curr, struct mutex, held_list);
-                t = lock->owner;
-                if (t != task->thread_info)
-                        continue;
-                list_del_init(curr);
-                DEBUG_OFF();
-                debug_spin_unlock_restore(&debug_mutex_lock, flags);
-
-                printk("BUG: %s/%d, lock held at task exit time!\n",
-                        task->comm, task->pid);
-                printk_lock(lock, 1);
-                if (lock->owner != task->thread_info)
-                        printk("exiting task is not even the owner??\n");
-                return;
-        }
-        debug_spin_unlock_restore(&debug_mutex_lock, flags);
-}
-
-/*
- * Called when kernel memory is freed (or unmapped), or if a mutex
- * is destroyed or reinitialized - this code checks whether there is
- * any held lock in the memory range of <from> to <to>:
- */
-void mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
-{
-        struct list_head *curr, *next;
-        const void *to = from + len;
-        unsigned long flags;
-        struct mutex *lock;
-        void *lock_addr;
-
-        if (!debug_mutex_on)
-                return;
-
-        debug_spin_lock_save(&debug_mutex_lock, flags);
-        list_for_each_safe(curr, next, &debug_mutex_held_locks) {
-                lock = list_entry(curr, struct mutex, held_list);
-                lock_addr = lock;
-                if (lock_addr < from || lock_addr >= to)
-                        continue;
-                list_del_init(curr);
-                DEBUG_OFF();
-                debug_spin_unlock_restore(&debug_mutex_lock, flags);
-
-                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 (lock->owner != current_thread_info())
-                        printk("freeing task is not even the owner??\n");
-                return;
-        }
-        debug_spin_unlock_restore(&debug_mutex_lock, flags);
-}
-
 /*
  * Must be called with lock->wait_lock held.
  */
@@ -405,7 +90,6 @@ void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
                             struct thread_info *ti __IP_DECL__)
 {
         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
-        check_deadlock(lock, 0, ti, ip);
         /* Mark the current thread as blocked on the lock: */
         ti->task->blocked_on = waiter;
         waiter->lock = lock;