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