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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/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/plist.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(!plist_head_empty(&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(int detect, struct rt_mutex_waiter *act_waiter,
 70                              struct rt_mutex *lock)
 71 {
 72         struct task_struct *task;
 73 
 74         if (!debug_locks || detect || !act_waiter)
 75                 return;
 76 
 77         task = rt_mutex_owner(act_waiter->lock);
 78         if (task && task != current) {
 79                 act_waiter->deadlock_task_pid = get_pid(task_pid(task));
 80                 act_waiter->deadlock_lock = lock;
 81         }
 82 }
 83 
 84 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
 85 {
 86         struct task_struct *task;
 87 
 88         if (!waiter->deadlock_lock || !debug_locks)
 89                 return;
 90 
 91         rcu_read_lock();
 92         task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
 93         if (!task) {
 94                 rcu_read_unlock();
 95                 return;
 96         }
 97 
 98         if (!debug_locks_off()) {
 99                 rcu_read_unlock();
100                 return;
101         }
102 
103         printk("\n============================================\n");
104         printk(  "[ BUG: circular locking deadlock detected! ]\n");
105         printk("%s\n", print_tainted());
106         printk(  "--------------------------------------------\n");
107         printk("%s/%d is deadlocking current task %s/%d\n\n",
108                task->comm, task_pid_nr(task),
109                current->comm, task_pid_nr(current));
110 
111         printk("\n1) %s/%d is trying to acquire this lock:\n",
112                current->comm, task_pid_nr(current));
113         printk_lock(waiter->lock, 1);
114 
115         printk("\n2) %s/%d is blocked on this lock:\n",
116                 task->comm, task_pid_nr(task));
117         printk_lock(waiter->deadlock_lock, 1);
118 
119         debug_show_held_locks(current);
120         debug_show_held_locks(task);
121 
122         printk("\n%s/%d's [blocked] stackdump:\n\n",
123                 task->comm, task_pid_nr(task));
124         show_stack(task, NULL);
125         printk("\n%s/%d's [current] stackdump:\n\n",
126                 current->comm, task_pid_nr(current));
127         dump_stack();
128         debug_show_all_locks();
129         rcu_read_unlock();
130 
131         printk("[ turning off deadlock detection."
132                "Please report this trace. ]\n\n");
133 }
134 
135 void debug_rt_mutex_lock(struct rt_mutex *lock)
136 {
137 }
138 
139 void debug_rt_mutex_unlock(struct rt_mutex *lock)
140 {
141         DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
142 }
143 
144 void
145 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
146 {
147 }
148 
149 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
150 {
151         DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
152 }
153 
154 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
155 {
156         memset(waiter, 0x11, sizeof(*waiter));
157         plist_node_init(&waiter->list_entry, MAX_PRIO);
158         plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
159         waiter->deadlock_task_pid = NULL;
160 }
161 
162 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
163 {
164         put_pid(waiter->deadlock_task_pid);
165         DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry));
166         DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
167         memset(waiter, 0x22, sizeof(*waiter));
168 }
169 
170 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
171 {
172         /*
173          * Make sure we are not reinitializing a held lock:
174          */
175         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
176         lock->name = name;
177 }
178 
179 void
180 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
181 {
182 }
183 
184 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
185 {
186 }
187 
188 

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