/* * 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/delay.h>#include <linux/module.h>#include <linux/spinlock.h>#include <linux/kallsyms.h>#include <linux/syscalls.h>#include <linux/interrupt.h>#include <linux/plist.h>#include <linux/fs.h>#include <linux/debug_locks.h> #include "rtmutex_common.h" # define TRACE_WARN_ON(x)			WARN_ON(x)# define TRACE_BUG_ON(x)			BUG_ON(x) # define TRACE_OFF()						\do {								\	if (rt_trace_on) {					\		rt_trace_on = 0;				\		console_verbose();				\		if (spin_is_locked(&current->pi_lock))		\			spin_unlock(&current->pi_lock);		\	}							\} while (0) # define TRACE_OFF_NOLOCK()					\do {								\	if (rt_trace_on) {					\		rt_trace_on = 0;				\		console_verbose();				\	}							\} while (0) # define TRACE_BUG_LOCKED()			\do {						\	TRACE_OFF();				\	BUG();					\} while (0) # define TRACE_WARN_ON_LOCKED(c)		\do {						\	if (unlikely(c)) {			\		TRACE_OFF();			\		WARN_ON(1);			\	}					\} while (0) # define TRACE_BUG_ON_LOCKED(c)			\do {						\	if (unlikely(c))			\		TRACE_BUG_LOCKED();		\} while (0) #ifdef CONFIG_SMP# define SMP_TRACE_BUG_ON_LOCKED(c)	TRACE_BUG_ON_LOCKED(c)#else# define SMP_TRACE_BUG_ON_LOCKED(c)	do { } while (0)#endif /* * deadlock detection flag. We turn it off when we detect * the first problem because we dont want to recurse back * into the tracing code when doing error printk or * executing a BUG(): */int rt_trace_on = 1; void deadlock_trace_off(void){	rt_trace_on = 0;} 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_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){	WARN_ON(!plist_head_empty(&task->pi_waiters));	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(int detect, struct rt_mutex_waiter *act_waiter,			     struct rt_mutex *lock){	struct task_struct *task; 	if (!rt_trace_on || detect || !act_waiter)		return; 	task = rt_mutex_owner(act_waiter->lock);	if (task && task != current) {		act_waiter->deadlock_task_pid = task->pid;		act_waiter->deadlock_lock = lock;	}} void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter){	struct task_struct *task; 	if (!waiter->deadlock_lock || !rt_trace_on)		return; 	task = find_task_by_pid(waiter->deadlock_task_pid);	if (!task)		return; 	TRACE_OFF_NOLOCK(); 	printk("\n============================================\n");	printk(  "[ BUG: circular locking deadlock detected! ]\n");	printk(  "--------------------------------------------\n");	printk("%s/%d is deadlocking current task %s/%d\n\n",	       task->comm, task->pid, current->comm, current->pid); 	printk("\n1) %s/%d is trying to acquire this lock:\n",	       current->comm, current->pid);	printk_lock(waiter->lock, 1); 	printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);	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);	show_stack(task, NULL);	printk("\n%s/%d's [current] stackdump:\n\n",	       current->comm, current->pid);	dump_stack();	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){} void debug_rt_mutex_unlock(struct rt_mutex *lock){	TRACE_WARN_ON_LOCKED(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){	TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));} void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter){	memset(waiter, 0x11, sizeof(*waiter));	plist_node_init(&waiter->list_entry, MAX_PRIO);	plist_node_init(&waiter->pi_list_entry, MAX_PRIO);} void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter){	TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));	TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));	TRACE_WARN_ON(waiter->task);	memset(waiter, 0x22, sizeof(*waiter));} void debug_rt_mutex_init(struct rt_mutex *lock, const char *name){	/*	 * Make sure we are not reinitializing a held lock:	 */	debug_check_no_locks_freed((void *)lock, sizeof(*lock));	lock->name = name;} voidrt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task){} void rt_mutex_deadlock_account_unlock(struct task_struct *task){}