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 static void printk_task(struct task_struct *p)
  33 {
  34         if (p)
  35                 printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
  36         else
  37                 printk("<none>");
  38 }
  39
  40 static void printk_lock(struct rt_mutex *lock, int print_owner)
  41 {
  42         if (lock->name)
  43                 printk(" [%p] {%s}\n",
  44                         lock, lock->name);
  45         else
  46                 printk(" [%p] {%s:%d}\n",
  47                         lock, lock->file, lock->line);
  48
  49         if (print_owner && rt_mutex_owner(lock)) {
  50                 printk(".. ->owner: %p\n", lock->owner);
  51                 printk(".. held by:  ");
  52                 printk_task(rt_mutex_owner(lock));
  53                 printk("\n");
  54         }
  55 }
  56
  57 void rt_mutex_debug_task_free(struct task_struct *task)
  58 {
  59         DEBUG_LOCKS_WARN_ON(!plist_head_empty(&task->pi_waiters));
  60         DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
  61 }
  62
  63 /*
  64  * We fill out the fields in the waiter to store the information about
  65  * the deadlock. We print when we return. act_waiter can be NULL in
  66  * case of a remove waiter operation.
  67  */
  68 void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
  69                              struct rt_mutex *lock)
  70 {
  71         struct task_struct *task;
  72
  73         if (!debug_locks || detect || !act_waiter)
  74                 return;
  75
  76         task = rt_mutex_owner(act_waiter->lock);
  77         if (task && task != current) {
  78                 act_waiter->deadlock_task_pid = get_pid(task_pid(task));
  79                 act_waiter->deadlock_lock = lock;
  80         }
  81 }
  82
  83 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
  84 {
  85         struct task_struct *task;
  86
  87         if (!waiter->deadlock_lock || !debug_locks)
  88                 return;
  89
  90         rcu_read_lock();
  91         task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
  92         if (!task) {
  93                 rcu_read_unlock();
  94                 return;
  95         }
  96
  97         if (!debug_locks_off()) {
  98                 rcu_read_unlock();
  99                 return;
 100         }
 101
 102         printk("\n============================================\n");
 103         printk(  "[ BUG: circular locking deadlock detected! ]\n");
 104         printk("%s\n", print_tainted());
 105         printk(  "--------------------------------------------\n");
 106         printk("%s/%d is deadlocking current task %s/%d\n\n",
 107                task->comm, task_pid_nr(task),
 108                current->comm, task_pid_nr(current));
 109
 110         printk("\n1) %s/%d is trying to acquire this lock:\n",
 111                current->comm, task_pid_nr(current));
 112         printk_lock(waiter->lock, 1);
 113
 114         printk("\n2) %s/%d is blocked on this lock:\n",
 115                 task->comm, task_pid_nr(task));
 116         printk_lock(waiter->deadlock_lock, 1);
 117
 118         debug_show_held_locks(current);
 119         debug_show_held_locks(task);
 120
 121         printk("\n%s/%d's [blocked] stackdump:\n\n",
 122                 task->comm, task_pid_nr(task));
 123         show_stack(task, NULL);
 124         printk("\n%s/%d's [current] stackdump:\n\n",
 125                 current->comm, task_pid_nr(current));
 126         dump_stack();
 127         debug_show_all_locks();
 128         rcu_read_unlock();
 129
 130         printk("[ turning off deadlock detection."
 131                "Please report this trace. ]\n\n");
 132 }
 133
 134 void debug_rt_mutex_lock(struct rt_mutex *lock)
 135 {
 136 }
 137
 138 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 139 {
 140         DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
 141 }
 142
 143 void
 144 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 145 {
 146 }
 147
 148 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 149 {
 150         DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
 151 }
 152
 153 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
 154 {
 155         memset(waiter, 0x11, sizeof(*waiter));
 156         plist_node_init(&waiter->list_entry, MAX_PRIO);
 157         plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
 158         waiter->deadlock_task_pid = NULL;
 159 }
 160
 161 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
 162 {
 163         put_pid(waiter->deadlock_task_pid);
 164         DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry));
 165         DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
 166         memset(waiter, 0x22, sizeof(*waiter));
 167 }
 168
 169 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
 170 {
 171         /*
 172          * Make sure we are not reinitializing a held lock:
 173          */
 174         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 175         lock->name = name;
 176 }
 177
 178 void
 179 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
 180 {
 181 }
 182
 183 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
 184 {
 185 }
 186