/* * RT-Mutexes: blocking mutual exclusion locks with PI support * * started by Ingo Molnar and Thomas Gleixner: * *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> * * This code is based on the rt.c implementation in the preempt-rt tree. * Portions of said code are * *  Copyright (C) 2004  LynuxWorks, Inc., Igor Manyilov, Bill Huey *  Copyright (C) 2006  Esben Nielsen *  Copyright (C) 2006  Kihon Technologies Inc., *			Steven Rostedt <rostedt@goodmis.org> * * See rt.c in preempt-rt for proper credits and further information */#include <linux/sched.h>#include <linux/sched/rt.h>#include <linux/sched/debug.h>#include <linux/delay.h>#include <linux/export.h>#include <linux/spinlock.h>#include <linux/kallsyms.h>#include <linux/syscalls.h>#include <linux/interrupt.h>#include <linux/rbtree.h>#include <linux/fs.h>#include <linux/debug_locks.h> #include "rtmutex_common.h" static void printk_task(struct task_struct *p){	if (p)		printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);	else		printk("<none>");} static void printk_lock(struct rt_mutex *lock, int print_owner){	if (lock->name)		printk(" [%p] {%s}\n",			lock, lock->name);	else		printk(" [%p] {%s:%d}\n",			lock, lock->file, lock->line); 	if (print_owner && rt_mutex_owner(lock)) {		printk(".. ->owner: %p\n", lock->owner);		printk(".. held by:  ");		printk_task(rt_mutex_owner(lock));		printk("\n");	}} void rt_mutex_debug_task_free(struct task_struct *task){	DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));	DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);} /* * We fill out the fields in the waiter to store the information about * the deadlock. We print when we return. act_waiter can be NULL in * case of a remove waiter operation. */void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,			     struct rt_mutex_waiter *act_waiter,			     struct rt_mutex *lock){	struct task_struct *task; 	if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)		return; 	task = rt_mutex_owner(act_waiter->lock);	if (task && task != current) {		act_waiter->deadlock_task_pid = get_pid(task_pid(task));		act_waiter->deadlock_lock = lock;	}} void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter){	struct task_struct *task; 	if (!waiter->deadlock_lock || !debug_locks)		return; 	rcu_read_lock();	task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);	if (!task) {		rcu_read_unlock();		return;	} 	if (!debug_locks_off()) {		rcu_read_unlock();		return;	} 	pr_warn("\n");	pr_warn("============================================\n");	pr_warn("WARNING: circular locking deadlock detected!\n");	pr_warn("%s\n", print_tainted());	pr_warn("--------------------------------------------\n");	printk("%s/%d is deadlocking current task %s/%d\n\n",	       task->comm, task_pid_nr(task),	       current->comm, task_pid_nr(current)); 	printk("\n1) %s/%d is trying to acquire this lock:\n",	       current->comm, task_pid_nr(current));	printk_lock(waiter->lock, 1); 	printk("\n2) %s/%d is blocked on this lock:\n",		task->comm, task_pid_nr(task));	printk_lock(waiter->deadlock_lock, 1); 	debug_show_held_locks(current);	debug_show_held_locks(task); 	printk("\n%s/%d's [blocked] stackdump:\n\n",		task->comm, task_pid_nr(task));	show_stack(task, NULL);	printk("\n%s/%d's [current] stackdump:\n\n",		current->comm, task_pid_nr(current));	dump_stack();	debug_show_all_locks();	rcu_read_unlock(); 	printk("[ turning off deadlock detection."	       "Please report this trace. ]\n\n");} void debug_rt_mutex_lock(struct rt_mutex *lock){} void debug_rt_mutex_unlock(struct rt_mutex *lock){	DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);} voiddebug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner){} void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock){	DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));} void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter){	memset(waiter, 0x11, sizeof(*waiter));	waiter->deadlock_task_pid = NULL;} void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter){	put_pid(waiter->deadlock_task_pid);	memset(waiter, 0x22, sizeof(*waiter));} void debug_rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key){	/*	 * Make sure we are not reinitializing a held lock:	 */	debug_check_no_locks_freed((void *)lock, sizeof(*lock));	lock->name = name; #ifdef CONFIG_DEBUG_LOCK_ALLOC	lockdep_init_map(&lock->dep_map, name, key, 0);#endif}