ia64/linux-2.6.18-xen.hg

view kernel/rtmutex-debug.c @ 562:66faefe721eb

pvSCSI backend driver

Signed-off-by: Tomonari Horikoshi <t.horikoshi@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Jun 02 09:58:27 2008 +0100 (2008-06-02)
parents 831230e53067
children
line source
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/config.h>
20 #include <linux/sched.h>
21 #include <linux/delay.h>
22 #include <linux/module.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>
31 #include "rtmutex_common.h"
33 #ifdef CONFIG_DEBUG_RT_MUTEXES
34 # include "rtmutex-debug.h"
35 #else
36 # include "rtmutex.h"
37 #endif
39 # define TRACE_WARN_ON(x) WARN_ON(x)
40 # define TRACE_BUG_ON(x) BUG_ON(x)
42 # define TRACE_OFF() \
43 do { \
44 if (rt_trace_on) { \
45 rt_trace_on = 0; \
46 console_verbose(); \
47 if (spin_is_locked(&current->pi_lock)) \
48 spin_unlock(&current->pi_lock); \
49 } \
50 } while (0)
52 # define TRACE_OFF_NOLOCK() \
53 do { \
54 if (rt_trace_on) { \
55 rt_trace_on = 0; \
56 console_verbose(); \
57 } \
58 } while (0)
60 # define TRACE_BUG_LOCKED() \
61 do { \
62 TRACE_OFF(); \
63 BUG(); \
64 } while (0)
66 # define TRACE_WARN_ON_LOCKED(c) \
67 do { \
68 if (unlikely(c)) { \
69 TRACE_OFF(); \
70 WARN_ON(1); \
71 } \
72 } while (0)
74 # define TRACE_BUG_ON_LOCKED(c) \
75 do { \
76 if (unlikely(c)) \
77 TRACE_BUG_LOCKED(); \
78 } while (0)
80 #ifdef CONFIG_SMP
81 # define SMP_TRACE_BUG_ON_LOCKED(c) TRACE_BUG_ON_LOCKED(c)
82 #else
83 # define SMP_TRACE_BUG_ON_LOCKED(c) do { } while (0)
84 #endif
86 /*
87 * deadlock detection flag. We turn it off when we detect
88 * the first problem because we dont want to recurse back
89 * into the tracing code when doing error printk or
90 * executing a BUG():
91 */
92 int rt_trace_on = 1;
94 void deadlock_trace_off(void)
95 {
96 rt_trace_on = 0;
97 }
99 static void printk_task(struct task_struct *p)
100 {
101 if (p)
102 printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
103 else
104 printk("<none>");
105 }
107 static void printk_lock(struct rt_mutex *lock, int print_owner)
108 {
109 if (lock->name)
110 printk(" [%p] {%s}\n",
111 lock, lock->name);
112 else
113 printk(" [%p] {%s:%d}\n",
114 lock, lock->file, lock->line);
116 if (print_owner && rt_mutex_owner(lock)) {
117 printk(".. ->owner: %p\n", lock->owner);
118 printk(".. held by: ");
119 printk_task(rt_mutex_owner(lock));
120 printk("\n");
121 }
122 }
124 void rt_mutex_debug_task_free(struct task_struct *task)
125 {
126 WARN_ON(!plist_head_empty(&task->pi_waiters));
127 WARN_ON(task->pi_blocked_on);
128 }
130 /*
131 * We fill out the fields in the waiter to store the information about
132 * the deadlock. We print when we return. act_waiter can be NULL in
133 * case of a remove waiter operation.
134 */
135 void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
136 struct rt_mutex *lock)
137 {
138 struct task_struct *task;
140 if (!rt_trace_on || detect || !act_waiter)
141 return;
143 task = rt_mutex_owner(act_waiter->lock);
144 if (task && task != current) {
145 act_waiter->deadlock_task_pid = task->pid;
146 act_waiter->deadlock_lock = lock;
147 }
148 }
150 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
151 {
152 struct task_struct *task;
154 if (!waiter->deadlock_lock || !rt_trace_on)
155 return;
157 task = find_task_by_pid(waiter->deadlock_task_pid);
158 if (!task)
159 return;
161 TRACE_OFF_NOLOCK();
163 printk("\n============================================\n");
164 printk( "[ BUG: circular locking deadlock detected! ]\n");
165 printk( "--------------------------------------------\n");
166 printk("%s/%d is deadlocking current task %s/%d\n\n",
167 task->comm, task->pid, current->comm, current->pid);
169 printk("\n1) %s/%d is trying to acquire this lock:\n",
170 current->comm, current->pid);
171 printk_lock(waiter->lock, 1);
173 printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
174 printk_lock(waiter->deadlock_lock, 1);
176 debug_show_held_locks(current);
177 debug_show_held_locks(task);
179 printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
180 show_stack(task, NULL);
181 printk("\n%s/%d's [current] stackdump:\n\n",
182 current->comm, current->pid);
183 dump_stack();
184 debug_show_all_locks();
186 printk("[ turning off deadlock detection."
187 "Please report this trace. ]\n\n");
188 local_irq_disable();
189 }
191 void debug_rt_mutex_lock(struct rt_mutex *lock)
192 {
193 }
195 void debug_rt_mutex_unlock(struct rt_mutex *lock)
196 {
197 TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
198 }
200 void
201 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
202 {
203 }
205 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
206 {
207 TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
208 }
210 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
211 {
212 memset(waiter, 0x11, sizeof(*waiter));
213 plist_node_init(&waiter->list_entry, MAX_PRIO);
214 plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
215 }
217 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
218 {
219 TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
220 TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
221 TRACE_WARN_ON(waiter->task);
222 memset(waiter, 0x22, sizeof(*waiter));
223 }
225 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
226 {
227 /*
228 * Make sure we are not reinitializing a held lock:
229 */
230 debug_check_no_locks_freed((void *)lock, sizeof(*lock));
231 lock->name = name;
232 }
234 void
235 rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
236 {
237 }
239 void rt_mutex_deadlock_account_unlock(struct task_struct *task)
240 {
241 }