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 # 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 (spin_is_locked(&current->pi_lock))          \
  41                         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 int rt_trace_on = 1;
  86
  87 void deadlock_trace_off(void)
  88 {
  89         rt_trace_on = 0;
  90 }
  91
  92 static void printk_task(struct task_struct *p)
  93 {
  94         if (p)
  95                 printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
  96         else
  97                 printk("<none>");
  98 }
  99
 100 static void printk_lock(struct rt_mutex *lock, int print_owner)
 101 {
 102         if (lock->name)
 103                 printk(" [%p] {%s}\n",
 104                         lock, lock->name);
 105         else
 106                 printk(" [%p] {%s:%d}\n",
 107                         lock, lock->file, lock->line);
 108
 109         if (print_owner && rt_mutex_owner(lock)) {
 110                 printk(".. ->owner: %p\n", lock->owner);
 111                 printk(".. held by:  ");
 112                 printk_task(rt_mutex_owner(lock));
 113                 printk("\n");
 114         }
 115 }
 116
 117 void rt_mutex_debug_task_free(struct task_struct *task)
 118 {
 119         WARN_ON(!plist_head_empty(&task->pi_waiters));
 120         WARN_ON(task->pi_blocked_on);
 121 }
 122
 123 /*
 124  * We fill out the fields in the waiter to store the information about
 125  * the deadlock. We print when we return. act_waiter can be NULL in
 126  * case of a remove waiter operation.
 127  */
 128 void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
 129                              struct rt_mutex *lock)
 130 {
 131         struct task_struct *task;
 132
 133         if (!rt_trace_on || detect || !act_waiter)
 134                 return;
 135
 136         task = rt_mutex_owner(act_waiter->lock);
 137         if (task && task != current) {
 138                 act_waiter->deadlock_task_pid = task->pid;
 139                 act_waiter->deadlock_lock = lock;
 140         }
 141 }
 142
 143 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
 144 {
 145         struct task_struct *task;
 146
 147         if (!waiter->deadlock_lock || !rt_trace_on)
 148                 return;
 149
 150         task = find_task_by_pid(waiter->deadlock_task_pid);
 151         if (!task)
 152                 return;
 153
 154         TRACE_OFF_NOLOCK();
 155
 156         printk("\n============================================\n");
 157         printk(  "[ BUG: circular locking deadlock detected! ]\n");
 158         printk(  "--------------------------------------------\n");
 159         printk("%s/%d is deadlocking current task %s/%d\n\n",
 160                task->comm, task->pid, current->comm, current->pid);
 161
 162         printk("\n1) %s/%d is trying to acquire this lock:\n",
 163                current->comm, current->pid);
 164         printk_lock(waiter->lock, 1);
 165
 166         printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
 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", task->comm, task->pid);
 173         show_stack(task, NULL);
 174         printk("\n%s/%d's [current] stackdump:\n\n",
 175                current->comm, current->pid);
 176         dump_stack();
 177         debug_show_all_locks();
 178
 179         printk("[ turning off deadlock detection."
 180                "Please report this trace. ]\n\n");
 181         local_irq_disable();
 182 }
 183
 184 void debug_rt_mutex_lock(struct rt_mutex *lock)
 185 {
 186 }
 187
 188 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 189 {
 190         TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
 191 }
 192
 193 void
 194 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 195 {
 196 }
 197
 198 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 199 {
 200         TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
 201 }
 202
 203 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
 204 {
 205         memset(waiter, 0x11, sizeof(*waiter));
 206         plist_node_init(&waiter->list_entry, MAX_PRIO);
 207         plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
 208 }
 209
 210 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
 211 {
 212         TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
 213         TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
 214         TRACE_WARN_ON(waiter->task);
 215         memset(waiter, 0x22, sizeof(*waiter));
 216 }
 217
 218 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
 219 {
 220         /*
 221          * Make sure we are not reinitializing a held lock:
 222          */
 223         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 224         lock->name = name;
 225 }
 226
 227 void
 228 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
 229 {
 230 }
 231
 232 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
 233 {
 234 }
 235