kernel/rtmutex-debug.c: cleanups
[linux-3.10.git] / 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 static int rt_trace_on = 1;
86
87 static void printk_task(struct task_struct *p)
88 {
89         if (p)
90                 printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
91         else
92                 printk("<none>");
93 }
94
95 static void printk_lock(struct rt_mutex *lock, int print_owner)
96 {
97         if (lock->name)
98                 printk(" [%p] {%s}\n",
99                         lock, lock->name);
100         else
101                 printk(" [%p] {%s:%d}\n",
102                         lock, lock->file, lock->line);
103
104         if (print_owner && rt_mutex_owner(lock)) {
105                 printk(".. ->owner: %p\n", lock->owner);
106                 printk(".. held by:  ");
107                 printk_task(rt_mutex_owner(lock));
108                 printk("\n");
109         }
110 }
111
112 void rt_mutex_debug_task_free(struct task_struct *task)
113 {
114         WARN_ON(!plist_head_empty(&task->pi_waiters));
115         WARN_ON(task->pi_blocked_on);
116 }
117
118 /*
119  * We fill out the fields in the waiter to store the information about
120  * the deadlock. We print when we return. act_waiter can be NULL in
121  * case of a remove waiter operation.
122  */
123 void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
124                              struct rt_mutex *lock)
125 {
126         struct task_struct *task;
127
128         if (!rt_trace_on || detect || !act_waiter)
129                 return;
130
131         task = rt_mutex_owner(act_waiter->lock);
132         if (task && task != current) {
133                 act_waiter->deadlock_task_pid = task->pid;
134                 act_waiter->deadlock_lock = lock;
135         }
136 }
137
138 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
139 {
140         struct task_struct *task;
141
142         if (!waiter->deadlock_lock || !rt_trace_on)
143                 return;
144
145         task = find_task_by_pid(waiter->deadlock_task_pid);
146         if (!task)
147                 return;
148
149         TRACE_OFF_NOLOCK();
150
151         printk("\n============================================\n");
152         printk(  "[ BUG: circular locking deadlock detected! ]\n");
153         printk(  "--------------------------------------------\n");
154         printk("%s/%d is deadlocking current task %s/%d\n\n",
155                task->comm, task->pid, current->comm, current->pid);
156
157         printk("\n1) %s/%d is trying to acquire this lock:\n",
158                current->comm, current->pid);
159         printk_lock(waiter->lock, 1);
160
161         printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
162         printk_lock(waiter->deadlock_lock, 1);
163
164         debug_show_held_locks(current);
165         debug_show_held_locks(task);
166
167         printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
168         show_stack(task, NULL);
169         printk("\n%s/%d's [current] stackdump:\n\n",
170                current->comm, current->pid);
171         dump_stack();
172         debug_show_all_locks();
173
174         printk("[ turning off deadlock detection."
175                "Please report this trace. ]\n\n");
176         local_irq_disable();
177 }
178
179 void debug_rt_mutex_lock(struct rt_mutex *lock)
180 {
181 }
182
183 void debug_rt_mutex_unlock(struct rt_mutex *lock)
184 {
185         TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
186 }
187
188 void
189 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
190 {
191 }
192
193 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
194 {
195         TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
196 }
197
198 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
199 {
200         memset(waiter, 0x11, sizeof(*waiter));
201         plist_node_init(&waiter->list_entry, MAX_PRIO);
202         plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
203 }
204
205 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
206 {
207         TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
208         TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
209         TRACE_WARN_ON(waiter->task);
210         memset(waiter, 0x22, sizeof(*waiter));
211 }
212
213 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
214 {
215         /*
216          * Make sure we are not reinitializing a held lock:
217          */
218         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
219         lock->name = name;
220 }
221
222 void
223 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
224 {
225 }
226
227 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
228 {
229 }
230