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/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()                                            \
  42 do {                                                            \
  43         if (rt_trace_on) {                                      \
  44                 rt_trace_on = 0;                                \
  45                 console_verbose();                              \
  46                 if (spin_is_locked(&current->pi_lock))          \
  47                         spin_unlock(&current->pi_lock);         \
  48         }                                                       \
  49 } while (0)
  50
  51 # define TRACE_OFF_NOLOCK()                                     \
  52 do {                                                            \
  53         if (rt_trace_on) {                                      \
  54                 rt_trace_on = 0;                                \
  55                 console_verbose();                              \
  56         }                                                       \
  57 } while (0)
  58
  59 # define TRACE_BUG_LOCKED()                     \
  60 do {                                            \
  61         TRACE_OFF();                            \
  62         BUG();                                  \
  63 } while (0)
  64
  65 # define TRACE_WARN_ON_LOCKED(c)                \
  66 do {                                            \
  67         if (unlikely(c)) {                      \
  68                 TRACE_OFF();                    \
  69                 WARN_ON(1);                     \
  70         }                                       \
  71 } while (0)
  72
  73 # define TRACE_BUG_ON_LOCKED(c)                 \
  74 do {                                            \
  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  */
  91 int rt_trace_on = 1;
  92
  93 void deadlock_trace_off(void)
  94 {
  95         rt_trace_on = 0;
  96 }
  97
  98 static 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
 106 static 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
 123 void 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  */
 134 void 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
 149 void 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
 190 void debug_rt_mutex_lock(struct rt_mutex *lock)
 191 {
 192 }
 193
 194 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 195 {
 196         TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
 197 }
 198
 199 void
 200 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 201 {
 202 }
 203
 204 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 205 {
 206         TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
 207 }
 208
 209 void 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
 216 void 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
 224 void 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
 233 void
 234 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
 235 {
 236 }
 237
 238 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
 239 {
 240 }
 241