blob: 56d73cb8826d86ff75ce0dea818ce658be11cf49 [file] [log] [blame]
Ingo Molnare7eebaf2006-06-27 02:54:55 -07001/*
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 */
Ingo Molnare7eebaf2006-06-27 02:54:55 -070019#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>
Ingo Molnar9a11b49a2006-07-03 00:24:33 -070028#include <linux/debug_locks.h>
Ingo Molnare7eebaf2006-06-27 02:54:55 -070029
30#include "rtmutex_common.h"
31
Ingo Molnare7eebaf2006-06-27 02:54:55 -070032# define TRACE_WARN_ON(x) WARN_ON(x)
33# define TRACE_BUG_ON(x) BUG_ON(x)
34
35# define TRACE_OFF() \
36do { \
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); \
Ingo Molnare7eebaf2006-06-27 02:54:55 -070042 } \
43} while (0)
44
45# define TRACE_OFF_NOLOCK() \
46do { \
47 if (rt_trace_on) { \
48 rt_trace_on = 0; \
49 console_verbose(); \
50 } \
51} while (0)
52
53# define TRACE_BUG_LOCKED() \
54do { \
55 TRACE_OFF(); \
56 BUG(); \
57} while (0)
58
59# define TRACE_WARN_ON_LOCKED(c) \
60do { \
61 if (unlikely(c)) { \
62 TRACE_OFF(); \
63 WARN_ON(1); \
64 } \
65} while (0)
66
67# define TRACE_BUG_ON_LOCKED(c) \
68do { \
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 */
Adrian Bunka4d63e72007-10-16 23:26:40 -070085static int rt_trace_on = 1;
Ingo Molnare7eebaf2006-06-27 02:54:55 -070086
Ingo Molnar36c8b582006-07-03 00:25:41 -070087static void printk_task(struct task_struct *p)
Ingo Molnare7eebaf2006-06-27 02:54:55 -070088{
89 if (p)
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -070090 printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
Ingo Molnare7eebaf2006-06-27 02:54:55 -070091 else
92 printk("<none>");
93}
94
Ingo Molnare7eebaf2006-06-27 02:54:55 -070095static 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 }
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700110}
111
112void 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 */
123void 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
138void 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",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700155 task->comm, task_pid_nr(task),
156 current->comm, task_pid_nr(current));
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700157
158 printk("\n1) %s/%d is trying to acquire this lock:\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700159 current->comm, task_pid_nr(current));
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700160 printk_lock(waiter->lock, 1);
161
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700162 printk("\n2) %s/%d is blocked on this lock:\n",
163 task->comm, task_pid_nr(task));
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700164 printk_lock(waiter->deadlock_lock, 1);
165
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700166 debug_show_held_locks(current);
167 debug_show_held_locks(task);
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700168
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700169 printk("\n%s/%d's [blocked] stackdump:\n\n",
170 task->comm, task_pid_nr(task));
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700171 show_stack(task, NULL);
172 printk("\n%s/%d's [current] stackdump:\n\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -0700173 current->comm, task_pid_nr(current));
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700174 dump_stack();
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700175 debug_show_all_locks();
176
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700177 printk("[ turning off deadlock detection."
178 "Please report this trace. ]\n\n");
179 local_irq_disable();
180}
181
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700182void debug_rt_mutex_lock(struct rt_mutex *lock)
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700183{
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700184}
185
186void debug_rt_mutex_unlock(struct rt_mutex *lock)
187{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700188 TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700189}
190
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700191void
192debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700193{
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700194}
195
196void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
197{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700198 TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700199}
200
201void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
202{
203 memset(waiter, 0x11, sizeof(*waiter));
204 plist_node_init(&waiter->list_entry, MAX_PRIO);
205 plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
206}
207
208void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
209{
210 TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
211 TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
212 TRACE_WARN_ON(waiter->task);
213 memset(waiter, 0x22, sizeof(*waiter));
214}
215
216void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
217{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700218 /*
219 * Make sure we are not reinitializing a held lock:
220 */
221 debug_check_no_locks_freed((void *)lock, sizeof(*lock));
222 lock->name = name;
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700223}
224
Ingo Molnar36c8b582006-07-03 00:25:41 -0700225void
226rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
Ingo Molnare7eebaf2006-06-27 02:54:55 -0700227{
228}
229
230void rt_mutex_deadlock_account_unlock(struct task_struct *task)
231{
232}
233