kernel/locking/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/sched/rt.h>
  21 #include <linux/delay.h>
  22 #include <linux/export.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/kallsyms.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/rbtree.h>
  28 #include <linux/fs.h>
  29 #include <linux/debug_locks.h>
  30
  31 #include "rtmutex_common.h"
  32
  33 static void printk_task(struct task_struct *p)
  34 {
  35         if (p)
  36                 printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
  37         else
  38                 printk("<none>");
  39 }
  40
  41 static void printk_lock(struct rt_mutex *lock, int print_owner)
  42 {
  43         if (lock->name)
  44                 printk(" [%p] {%s}\n",
  45                         lock, lock->name);
  46         else
  47                 printk(" [%p] {%s:%d}\n",
  48                         lock, lock->file, lock->line);
  49
  50         if (print_owner && rt_mutex_owner(lock)) {
  51                 printk(".. ->owner: %p\n", lock->owner);
  52                 printk(".. held by:  ");
  53                 printk_task(rt_mutex_owner(lock));
  54                 printk("\n");
  55         }
  56 }
  57
  58 void rt_mutex_debug_task_free(struct task_struct *task)
  59 {
  60         DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters));
  61         DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
  62 }
  63
  64 /*
  65  * We fill out the fields in the waiter to store the information about
  66  * the deadlock. We print when we return. act_waiter can be NULL in
  67  * case of a remove waiter operation.
  68  */
  69 void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
  70                              struct rt_mutex_waiter *act_waiter,
  71                              struct rt_mutex *lock)
  72 {
  73         struct task_struct *task;
  74
  75         if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)
  76                 return;
  77
  78         task = rt_mutex_owner(act_waiter->lock);
  79         if (task && task != current) {
  80                 act_waiter->deadlock_task_pid = get_pid(task_pid(task));
  81                 act_waiter->deadlock_lock = lock;
  82         }
  83 }
  84
  85 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
  86 {
  87         struct task_struct *task;
  88
  89         if (!waiter->deadlock_lock || !debug_locks)
  90                 return;
  91
  92         rcu_read_lock();
  93         task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
  94         if (!task) {
  95                 rcu_read_unlock();
  96                 return;
  97         }
  98
  99         if (!debug_locks_off()) {
 100                 rcu_read_unlock();
 101                 return;
 102         }
 103
 104         printk("\n============================================\n");
 105         printk(  "[ BUG: circular locking deadlock detected! ]\n");
 106         printk("%s\n", print_tainted());
 107         printk(  "--------------------------------------------\n");
 108         printk("%s/%d is deadlocking current task %s/%d\n\n",
 109                task->comm, task_pid_nr(task),
 110                current->comm, task_pid_nr(current));
 111
 112         printk("\n1) %s/%d is trying to acquire this lock:\n",
 113                current->comm, task_pid_nr(current));
 114         printk_lock(waiter->lock, 1);
 115
 116         printk("\n2) %s/%d is blocked on this lock:\n",
 117                 task->comm, task_pid_nr(task));
 118         printk_lock(waiter->deadlock_lock, 1);
 119
 120         debug_show_held_locks(current);
 121         debug_show_held_locks(task);
 122
 123         printk("\n%s/%d's [blocked] stackdump:\n\n",
 124                 task->comm, task_pid_nr(task));
 125         show_stack(task, NULL);
 126         printk("\n%s/%d's [current] stackdump:\n\n",
 127                 current->comm, task_pid_nr(current));
 128         dump_stack();
 129         debug_show_all_locks();
 130         rcu_read_unlock();
 131
 132         printk("[ turning off deadlock detection."
 133                "Please report this trace. ]\n\n");
 134 }
 135
 136 void debug_rt_mutex_lock(struct rt_mutex *lock)
 137 {
 138 }
 139
 140 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 141 {
 142         DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
 143 }
 144
 145 void
 146 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 147 {
 148 }
 149
 150 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 151 {
 152         DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
 153 }
 154
 155 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
 156 {
 157         memset(waiter, 0x11, sizeof(*waiter));
 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         memset(waiter, 0x22, sizeof(*waiter));
 165 }
 166
 167 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
 168 {
 169         /*
 170          * Make sure we are not reinitializing a held lock:
 171          */
 172         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 173         lock->name = name;
 174 }
 175
 176 void
 177 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
 178 {
 179 }
 180
 181 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
 182 {
 183 }
 184