forked from Minki/linux
[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>
This commit is contained in:
Ingo Molnar
Linus Torvalds
parent
36596243da
commit
fb7e42413a
@ -51,321 +51,6 @@ LIST_HEAD(debug_mutex_held_locks);
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*/
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int debug_mutex_on = 1;
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static void printk_task(struct task_struct *p)
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{
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if (p)
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printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
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else
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printk("<none>");
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}
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static void printk_ti(struct thread_info *ti)
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{
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if (ti)
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printk_task(ti->task);
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else
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printk("<none>");
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}
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static void printk_task_short(struct task_struct *p)
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{
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if (p)
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printk("%s/%d [%p, %3d]", p->comm, p->pid, p, p->prio);
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else
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printk("<none>");
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}
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static void printk_lock(struct mutex *lock, int print_owner)
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{
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printk(" [%p] {%s}\n", lock, lock->name);
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if (print_owner && lock->owner) {
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printk(".. held by: ");
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printk_ti(lock->owner);
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printk("\n");
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}
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if (lock->owner) {
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printk("... acquired at: ");
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print_symbol("%s\n", lock->acquire_ip);
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}
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}
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/*
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* printk locks held by a task:
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*/
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static void show_task_locks(struct task_struct *p)
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{
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switch (p->state) {
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case TASK_RUNNING: printk("R"); break;
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case TASK_INTERRUPTIBLE: printk("S"); break;
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case TASK_UNINTERRUPTIBLE: printk("D"); break;
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case TASK_STOPPED: printk("T"); break;
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case EXIT_ZOMBIE: printk("Z"); break;
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case EXIT_DEAD: printk("X"); break;
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default: printk("?"); break;
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}
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printk_task(p);
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if (p->blocked_on) {
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struct mutex *lock = p->blocked_on->lock;
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printk(" blocked on mutex:");
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printk_lock(lock, 1);
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} else
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printk(" (not blocked on mutex)\n");
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}
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/*
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* printk all locks held in the system (if filter == NULL),
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* or all locks belonging to a single task (if filter != NULL):
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*/
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void show_held_locks(struct task_struct *filter)
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{
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struct list_head *curr, *cursor = NULL;
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struct mutex *lock;
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struct thread_info *t;
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unsigned long flags;
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int count = 0;
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if (filter) {
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printk("------------------------------\n");
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printk("| showing all locks held by: | (");
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printk_task_short(filter);
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printk("):\n");
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printk("------------------------------\n");
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} else {
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printk("---------------------------\n");
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printk("| showing all locks held: |\n");
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printk("---------------------------\n");
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}
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/*
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* Play safe and acquire the global trace lock. We
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* cannot printk with that lock held so we iterate
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* very carefully:
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*/
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next:
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debug_spin_lock_save(&debug_mutex_lock, flags);
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list_for_each(curr, &debug_mutex_held_locks) {
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if (cursor && curr != cursor)
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continue;
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lock = list_entry(curr, struct mutex, held_list);
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t = lock->owner;
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if (filter && (t != filter->thread_info))
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continue;
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count++;
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cursor = curr->next;
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debug_spin_unlock_restore(&debug_mutex_lock, flags);
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printk("\n#%03d: ", count);
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printk_lock(lock, filter ? 0 : 1);
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goto next;
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}
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debug_spin_unlock_restore(&debug_mutex_lock, flags);
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printk("\n");
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}
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void mutex_debug_show_all_locks(void)
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{
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struct task_struct *g, *p;
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int count = 10;
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int unlock = 1;
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printk("\nShowing all blocking locks in the system:\n");
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/*
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* Here we try to get the tasklist_lock as hard as possible,
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* if not successful after 2 seconds we ignore it (but keep
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* trying). This is to enable a debug printout even if a
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* tasklist_lock-holding task deadlocks or crashes.
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*/
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retry:
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if (!read_trylock(&tasklist_lock)) {
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if (count == 10)
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printk("hm, tasklist_lock locked, retrying... ");
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if (count) {
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count--;
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printk(" #%d", 10-count);
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mdelay(200);
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goto retry;
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}
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printk(" ignoring it.\n");
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unlock = 0;
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}
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if (count != 10)
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printk(" locked it.\n");
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do_each_thread(g, p) {
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show_task_locks(p);
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if (!unlock)
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if (read_trylock(&tasklist_lock))
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unlock = 1;
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} while_each_thread(g, p);
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printk("\n");
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show_held_locks(NULL);
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printk("=============================================\n\n");
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if (unlock)
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read_unlock(&tasklist_lock);
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}
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static void report_deadlock(struct task_struct *task, struct mutex *lock,
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struct mutex *lockblk, unsigned long ip)
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{
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printk("\n%s/%d is trying to acquire this lock:\n",
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current->comm, current->pid);
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printk_lock(lock, 1);
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printk("... trying at: ");
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print_symbol("%s\n", ip);
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show_held_locks(current);
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if (lockblk) {
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printk("but %s/%d is deadlocking current task %s/%d!\n\n",
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task->comm, task->pid, current->comm, current->pid);
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printk("\n%s/%d is blocked on this lock:\n",
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task->comm, task->pid);
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printk_lock(lockblk, 1);
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show_held_locks(task);
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printk("\n%s/%d's [blocked] stackdump:\n\n",
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task->comm, task->pid);
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show_stack(task, NULL);
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}
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printk("\n%s/%d's [current] stackdump:\n\n",
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current->comm, current->pid);
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dump_stack();
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mutex_debug_show_all_locks();
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printk("[ turning off deadlock detection. Please report this. ]\n\n");
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local_irq_disable();
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}
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/*
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* Recursively check for mutex deadlocks:
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*/
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static int check_deadlock(struct mutex *lock, int depth,
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struct thread_info *ti, unsigned long ip)
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{
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struct mutex *lockblk;
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struct task_struct *task;
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if (!debug_mutex_on)
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return 0;
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ti = lock->owner;
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if (!ti)
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return 0;
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task = ti->task;
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lockblk = NULL;
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if (task->blocked_on)
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lockblk = task->blocked_on->lock;
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/* Self-deadlock: */
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if (current == task) {
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DEBUG_OFF();
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if (depth)
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return 1;
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printk("\n==========================================\n");
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printk( "[ BUG: lock recursion deadlock detected! |\n");
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printk( "------------------------------------------\n");
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report_deadlock(task, lock, NULL, ip);
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return 0;
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}
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/* Ugh, something corrupted the lock data structure? */
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if (depth > 20) {
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DEBUG_OFF();
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printk("\n===========================================\n");
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printk( "[ BUG: infinite lock dependency detected!? |\n");
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printk( "-------------------------------------------\n");
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report_deadlock(task, lock, lockblk, ip);
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return 0;
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}
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/* Recursively check for dependencies: */
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if (lockblk && check_deadlock(lockblk, depth+1, ti, ip)) {
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printk("\n============================================\n");
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printk( "[ BUG: circular locking deadlock detected! ]\n");
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printk( "--------------------------------------------\n");
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report_deadlock(task, lock, lockblk, ip);
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return 0;
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}
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return 0;
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}
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/*
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* Called when a task exits, this function checks whether the
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* task is holding any locks, and reports the first one if so:
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*/
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void mutex_debug_check_no_locks_held(struct task_struct *task)
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{
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struct list_head *curr, *next;
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struct thread_info *t;
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unsigned long flags;
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struct mutex *lock;
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if (!debug_mutex_on)
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return;
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debug_spin_lock_save(&debug_mutex_lock, flags);
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list_for_each_safe(curr, next, &debug_mutex_held_locks) {
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lock = list_entry(curr, struct mutex, held_list);
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t = lock->owner;
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if (t != task->thread_info)
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continue;
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list_del_init(curr);
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DEBUG_OFF();
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debug_spin_unlock_restore(&debug_mutex_lock, flags);
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printk("BUG: %s/%d, lock held at task exit time!\n",
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task->comm, task->pid);
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printk_lock(lock, 1);
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if (lock->owner != task->thread_info)
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printk("exiting task is not even the owner??\n");
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return;
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}
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debug_spin_unlock_restore(&debug_mutex_lock, flags);
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}
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/*
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* Called when kernel memory is freed (or unmapped), or if a mutex
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* is destroyed or reinitialized - this code checks whether there is
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* any held lock in the memory range of <from> to <to>:
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*/
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void mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
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{
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struct list_head *curr, *next;
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const void *to = from + len;
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unsigned long flags;
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struct mutex *lock;
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void *lock_addr;
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if (!debug_mutex_on)
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return;
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debug_spin_lock_save(&debug_mutex_lock, flags);
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list_for_each_safe(curr, next, &debug_mutex_held_locks) {
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lock = list_entry(curr, struct mutex, held_list);
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lock_addr = lock;
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if (lock_addr < from || lock_addr >= to)
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continue;
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list_del_init(curr);
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DEBUG_OFF();
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debug_spin_unlock_restore(&debug_mutex_lock, flags);
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printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
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current->comm, current->pid, lock, from, to);
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dump_stack();
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printk_lock(lock, 1);
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if (lock->owner != current_thread_info())
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printk("freeing task is not even the owner??\n");
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return;
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}
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debug_spin_unlock_restore(&debug_mutex_lock, flags);
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}
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/*
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* Must be called with lock->wait_lock held.
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*/
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@ -405,7 +90,6 @@ void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
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struct thread_info *ti __IP_DECL__)
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{
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SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
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check_deadlock(lock, 0, ti, ip);
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/* Mark the current thread as blocked on the lock: */
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ti->task->blocked_on = waiter;
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waiter->lock = lock;
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@ -115,14 +115,6 @@ config DEBUG_PREEMPT
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if kernel code uses it in a preemption-unsafe way. Also, the kernel
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will detect preemption count underflows.
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config DEBUG_MUTEXES
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bool "Mutex debugging, deadlock detection"
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default n
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depends on DEBUG_KERNEL
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help
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This allows mutex semantics violations and mutex related deadlocks
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(lockups) to be detected and reported automatically.
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config DEBUG_RT_MUTEXES
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bool "RT Mutex debugging, deadlock detection"
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depends on DEBUG_KERNEL && RT_MUTEXES
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