1/* 2 * RT-Mutexes: blocking mutual exclusion locks with PI support 3 * 4 * started by Ingo Molnar and Thomas Gleixner: 5 * 6 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> 7 * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com> 8 * 9 * This code is based on the rt.c implementation in the preempt-rt tree. 10 * Portions of said code are 11 * 12 * Copyright (C) 2004 LynuxWorks, Inc., Igor Manyilov, Bill Huey 13 * Copyright (C) 2006 Esben Nielsen 14 * Copyright (C) 2006 Kihon Technologies Inc., 15 * Steven Rostedt <rostedt@goodmis.org> 16 * 17 * See rt.c in preempt-rt for proper credits and further information 18 */ 19#include <linux/sched.h> 20#include <linux/delay.h> 21#include <linux/module.h> 22#include <linux/spinlock.h> 23#include <linux/kallsyms.h> 24#include <linux/syscalls.h> 25#include <linux/interrupt.h> 26#include <linux/plist.h> 27#include <linux/fs.h> 28#include <linux/debug_locks.h> 29 30#include "rtmutex_common.h" 31 32#ifdef CONFIG_DEBUG_RT_MUTEXES 33# include "rtmutex-debug.h" 34#else 35# include "rtmutex.h" 36#endif 37 38# define TRACE_WARN_ON(x) WARN_ON(x) 39# define TRACE_BUG_ON(x) BUG_ON(x) 40 41# define TRACE_OFF() \ 42do { \ 43 if (rt_trace_on) { \ 44 rt_trace_on = 0; \ 45 console_verbose(); \ 46 if (spin_is_locked(¤t->pi_lock)) \ 47 spin_unlock(¤t->pi_lock); \ 48 } \ 49} while (0) 50 51# define TRACE_OFF_NOLOCK() \ 52do { \ 53 if (rt_trace_on) { \ 54 rt_trace_on = 0; \ 55 console_verbose(); \ 56 } \ 57} while (0) 58 59# define TRACE_BUG_LOCKED() \ 60do { \ 61 TRACE_OFF(); \ 62 BUG(); \ 63} while (0) 64 65# define TRACE_WARN_ON_LOCKED(c) \ 66do { \ 67 if (unlikely(c)) { \ 68 TRACE_OFF(); \ 69 WARN_ON(1); \ 70 } \ 71} while (0) 72 73# define TRACE_BUG_ON_LOCKED(c) \ 74do { \ 75 if (unlikely(c)) \ 76 TRACE_BUG_LOCKED(); \ 77} while (0) 78 79#ifdef CONFIG_SMP 80# define SMP_TRACE_BUG_ON_LOCKED(c) TRACE_BUG_ON_LOCKED(c) 81#else 82# define SMP_TRACE_BUG_ON_LOCKED(c) do { } while (0) 83#endif 84 85/* 86 * deadlock detection flag. We turn it off when we detect 87 * the first problem because we dont want to recurse back 88 * into the tracing code when doing error printk or 89 * executing a BUG(): 90 */ 91int rt_trace_on = 1; 92 93void deadlock_trace_off(void) 94{ 95 rt_trace_on = 0; 96} 97 98static void printk_task(struct task_struct *p) 99{ 100 if (p) 101 printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio); 102 else 103 printk("<none>"); 104} 105 106static void printk_lock(struct rt_mutex *lock, int print_owner) 107{ 108 if (lock->name) 109 printk(" [%p] {%s}\n", 110 lock, lock->name); 111 else 112 printk(" [%p] {%s:%d}\n", 113 lock, lock->file, lock->line); 114 115 if (print_owner && rt_mutex_owner(lock)) { 116 printk(".. ->owner: %p\n", lock->owner); 117 printk(".. held by: "); 118 printk_task(rt_mutex_owner(lock)); 119 printk("\n"); 120 } 121} 122 123void rt_mutex_debug_task_free(struct task_struct *task) 124{ 125 WARN_ON(!plist_head_empty(&task->pi_waiters)); 126 WARN_ON(task->pi_blocked_on); 127} 128 129/* 130 * We fill out the fields in the waiter to store the information about 131 * the deadlock. We print when we return. act_waiter can be NULL in 132 * case of a remove waiter operation. 133 */ 134void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter, 135 struct rt_mutex *lock) 136{ 137 struct task_struct *task; 138 139 if (!rt_trace_on || detect || !act_waiter) 140 return; 141 142 task = rt_mutex_owner(act_waiter->lock); 143 if (task && task != current) { 144 act_waiter->deadlock_task_pid = task->pid; 145 act_waiter->deadlock_lock = lock; 146 } 147} 148 149void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter) 150{ 151 struct task_struct *task; 152 153 if (!waiter->deadlock_lock || !rt_trace_on) 154 return; 155 156 task = find_task_by_pid(waiter->deadlock_task_pid); 157 if (!task) 158 return; 159 160 TRACE_OFF_NOLOCK(); 161 162 printk("\n============================================\n"); 163 printk( "[ BUG: circular locking deadlock detected! ]\n"); 164 printk( "--------------------------------------------\n"); 165 printk("%s/%d is deadlocking current task %s/%d\n\n", 166 task->comm, task->pid, current->comm, current->pid); 167 168 printk("\n1) %s/%d is trying to acquire this lock:\n", 169 current->comm, current->pid); 170 printk_lock(waiter->lock, 1); 171 172 printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid); 173 printk_lock(waiter->deadlock_lock, 1); 174 175 debug_show_held_locks(current); 176 debug_show_held_locks(task); 177 178 printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid); 179 show_stack(task, NULL); 180 printk("\n%s/%d's [current] stackdump:\n\n", 181 current->comm, current->pid); 182 dump_stack(); 183 debug_show_all_locks(); 184 185 printk("[ turning off deadlock detection." 186 "Please report this trace. ]\n\n"); 187 local_irq_disable(); 188} 189 190void debug_rt_mutex_lock(struct rt_mutex *lock) 191{ 192} 193 194void debug_rt_mutex_unlock(struct rt_mutex *lock) 195{ 196 TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current); 197} 198 199void 200debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner) 201{ 202} 203 204void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock) 205{ 206 TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock)); 207} 208 209void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) 210{ 211 memset(waiter, 0x11, sizeof(*waiter)); 212 plist_node_init(&waiter->list_entry, MAX_PRIO); 213 plist_node_init(&waiter->pi_list_entry, MAX_PRIO); 214} 215 216void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter) 217{ 218 TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry)); 219 TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); 220 TRACE_WARN_ON(waiter->task); 221 memset(waiter, 0x22, sizeof(*waiter)); 222} 223 224void debug_rt_mutex_init(struct rt_mutex *lock, const char *name) 225{ 226 /* 227 * Make sure we are not reinitializing a held lock: 228 */ 229 debug_check_no_locks_freed((void *)lock, sizeof(*lock)); 230 lock->name = name; 231} 232 233void 234rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task) 235{ 236} 237 238void rt_mutex_deadlock_account_unlock(struct task_struct *task) 239{ 240} 241