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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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