linux/kernel/rtmutex-debug.c
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   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
  32static 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
  40static 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
  57void 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 */
  68void 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
  83void 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
 134void debug_rt_mutex_lock(struct rt_mutex *lock)
 135{
 136}
 137
 138void debug_rt_mutex_unlock(struct rt_mutex *lock)
 139{
 140        DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
 141}
 142
 143void
 144debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 145{
 146}
 147
 148void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 149{
 150        DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
 151}
 152
 153void 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
 161void 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
 169void 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
 178void
 179rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
 180{
 181}
 182
 183void rt_mutex_deadlock_account_unlock(struct task_struct *task)
 184{
 185}
 186
 187
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