kernel/rtmutex-debug.c

   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/config.h>
  20 #include <linux/sched.h>
  21 #include <linux/delay.h>
  22 #include <linux/module.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/kallsyms.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/plist.h>
  28 #include <linux/fs.h>
  29 #include <linux/debug_locks.h>
  30
  31 #include "rtmutex_common.h"
  32
  33 #ifdef CONFIG_DEBUG_RT_MUTEXES
  34 # include "rtmutex-debug.h"
  35 #else
  36 # include "rtmutex.h"
  37 #endif
  38
  39 # define TRACE_WARN_ON(x)                       WARN_ON(x)
  40 # define TRACE_BUG_ON(x)                        BUG_ON(x)
  41
  42 # define TRACE_OFF()                                            \
  43 do {                                                            \
  44         if (rt_trace_on) {                                      \
  45                 rt_trace_on = 0;                                \
  46                 console_verbose();                              \
  47                 if (spin_is_locked(&current->pi_lock))          \
  48                         spin_unlock(&current->pi_lock);         \
  49         }                                                       \
  50 } while (0)
  51
  52 # define TRACE_OFF_NOLOCK()                                     \
  53 do {                                                            \
  54         if (rt_trace_on) {                                      \
  55                 rt_trace_on = 0;                                \
  56                 console_verbose();                              \
  57         }                                                       \
  58 } while (0)
  59
  60 # define TRACE_BUG_LOCKED()                     \
  61 do {                                            \
  62         TRACE_OFF();                            \
  63         BUG();                                  \
  64 } while (0)
  65
  66 # define TRACE_WARN_ON_LOCKED(c)                \
  67 do {                                            \
  68         if (unlikely(c)) {                      \
  69                 TRACE_OFF();                    \
  70                 WARN_ON(1);                     \
  71         }                                       \
  72 } while (0)
  73
  74 # define TRACE_BUG_ON_LOCKED(c)                 \
  75 do {                                            \
  76         if (unlikely(c))                        \
  77                 TRACE_BUG_LOCKED();             \
  78 } while (0)
  79
  80 #ifdef CONFIG_SMP
  81 # define SMP_TRACE_BUG_ON_LOCKED(c)     TRACE_BUG_ON_LOCKED(c)
  82 #else
  83 # define SMP_TRACE_BUG_ON_LOCKED(c)     do { } while (0)
  84 #endif
  85
  86 /*
  87  * deadlock detection flag. We turn it off when we detect
  88  * the first problem because we dont want to recurse back
  89  * into the tracing code when doing error printk or
  90  * executing a BUG():
  91  */
  92 int rt_trace_on = 1;
  93
  94 void deadlock_trace_off(void)
  95 {
  96         rt_trace_on = 0;
  97 }
  98
  99 static void printk_task(struct task_struct *p)
 100 {
 101         if (p)
 102                 printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
 103         else
 104                 printk("<none>");
 105 }
 106
 107 static void printk_lock(struct rt_mutex *lock, int print_owner)
 108 {
 109         if (lock->name)
 110                 printk(" [%p] {%s}\n",
 111                         lock, lock->name);
 112         else
 113                 printk(" [%p] {%s:%d}\n",
 114                         lock, lock->file, lock->line);
 115
 116         if (print_owner && rt_mutex_owner(lock)) {
 117                 printk(".. ->owner: %p\n", lock->owner);
 118                 printk(".. held by:  ");
 119                 printk_task(rt_mutex_owner(lock));
 120                 printk("\n");
 121         }
 122 }
 123
 124 void rt_mutex_debug_task_free(struct task_struct *task)
 125 {
 126         WARN_ON(!plist_head_empty(&task->pi_waiters));
 127         WARN_ON(task->pi_blocked_on);
 128 }
 129
 130 /*
 131  * We fill out the fields in the waiter to store the information about
 132  * the deadlock. We print when we return. act_waiter can be NULL in
 133  * case of a remove waiter operation.
 134  */
 135 void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
 136                              struct rt_mutex *lock)
 137 {
 138         struct task_struct *task;
 139
 140         if (!rt_trace_on || detect || !act_waiter)
 141                 return;
 142
 143         task = rt_mutex_owner(act_waiter->lock);
 144         if (task && task != current) {
 145                 act_waiter->deadlock_task_pid = task->pid;
 146                 act_waiter->deadlock_lock = lock;
 147         }
 148 }
 149
 150 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
 151 {
 152         struct task_struct *task;
 153
 154         if (!waiter->deadlock_lock || !rt_trace_on)
 155                 return;
 156
 157         task = find_task_by_pid(waiter->deadlock_task_pid);
 158         if (!task)
 159                 return;
 160
 161         TRACE_OFF_NOLOCK();
 162
 163         printk("\n============================================\n");
 164         printk(  "[ BUG: circular locking deadlock detected! ]\n");
 165         printk(  "--------------------------------------------\n");
 166         printk("%s/%d is deadlocking current task %s/%d\n\n",
 167                task->comm, task->pid, current->comm, current->pid);
 168
 169         printk("\n1) %s/%d is trying to acquire this lock:\n",
 170                current->comm, current->pid);
 171         printk_lock(waiter->lock, 1);
 172
 173         printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
 174         printk_lock(waiter->deadlock_lock, 1);
 175
 176         debug_show_held_locks(current);
 177         debug_show_held_locks(task);
 178
 179         printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
 180         show_stack(task, NULL);
 181         printk("\n%s/%d's [current] stackdump:\n\n",
 182                current->comm, current->pid);
 183         dump_stack();
 184         debug_show_all_locks();
 185
 186         printk("[ turning off deadlock detection."
 187                "Please report this trace. ]\n\n");
 188         local_irq_disable();
 189 }
 190
 191 void debug_rt_mutex_lock(struct rt_mutex *lock)
 192 {
 193 }
 194
 195 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 196 {
 197         TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
 198 }
 199
 200 void
 201 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 202 {
 203 }
 204
 205 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 206 {
 207         TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
 208 }
 209
 210 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
 211 {
 212         memset(waiter, 0x11, sizeof(*waiter));
 213         plist_node_init(&waiter->list_entry, MAX_PRIO);
 214         plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
 215 }
 216
 217 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
 218 {
 219         TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
 220         TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
 221         TRACE_WARN_ON(waiter->task);
 222         memset(waiter, 0x22, sizeof(*waiter));
 223 }
 224
 225 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
 226 {
 227         /*
 228          * Make sure we are not reinitializing a held lock:
 229          */
 230         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 231         lock->name = name;
 232 }
 233
 234 void
 235 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
 236 {
 237 }
 238
 239 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
 240 {
 241 }
 242