2 * RT-Mutexes: blocking mutual exclusion locks with PI support
4 * started by Ingo Molnar and Thomas Gleixner:
6 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
7 * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
9 * This code is based on the rt.c implementation in the preempt-rt tree.
10 * Portions of said code are
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>
17 * See rt.c in preempt-rt for proper credits and further information
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>
28 #include <linux/debug_locks.h>
30 #include "rtmutex_common.h"
32 # define TRACE_WARN_ON(x) WARN_ON(x)
33 # define TRACE_BUG_ON(x) BUG_ON(x)
35 # define TRACE_OFF() \
40 if (spin_is_locked(¤t->pi_lock)) \
41 spin_unlock(¤t->pi_lock); \
45 # define TRACE_OFF_NOLOCK() \
53 # define TRACE_BUG_LOCKED() \
59 # define TRACE_WARN_ON_LOCKED(c) \
67 # define TRACE_BUG_ON_LOCKED(c) \
74 # define SMP_TRACE_BUG_ON_LOCKED(c) TRACE_BUG_ON_LOCKED(c)
76 # define SMP_TRACE_BUG_ON_LOCKED(c) do { } while (0)
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
87 void deadlock_trace_off(void)
92 static void printk_task(struct task_struct
*p
)
95 printk("%16s:%5d [%p, %3d]", p
->comm
, p
->pid
, p
, p
->prio
);
100 static void printk_lock(struct rt_mutex
*lock
, int print_owner
)
103 printk(" [%p] {%s}\n",
106 printk(" [%p] {%s:%d}\n",
107 lock
, lock
->file
, lock
->line
);
109 if (print_owner
&& rt_mutex_owner(lock
)) {
110 printk(".. ->owner: %p\n", lock
->owner
);
111 printk(".. held by: ");
112 printk_task(rt_mutex_owner(lock
));
117 void rt_mutex_debug_task_free(struct task_struct
*task
)
119 WARN_ON(!plist_head_empty(&task
->pi_waiters
));
120 WARN_ON(task
->pi_blocked_on
);
124 * We fill out the fields in the waiter to store the information about
125 * the deadlock. We print when we return. act_waiter can be NULL in
126 * case of a remove waiter operation.
128 void debug_rt_mutex_deadlock(int detect
, struct rt_mutex_waiter
*act_waiter
,
129 struct rt_mutex
*lock
)
131 struct task_struct
*task
;
133 if (!rt_trace_on
|| detect
|| !act_waiter
)
136 task
= rt_mutex_owner(act_waiter
->lock
);
137 if (task
&& task
!= current
) {
138 act_waiter
->deadlock_task_pid
= task
->pid
;
139 act_waiter
->deadlock_lock
= lock
;
143 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter
*waiter
)
145 struct task_struct
*task
;
147 if (!waiter
->deadlock_lock
|| !rt_trace_on
)
150 task
= find_task_by_pid(waiter
->deadlock_task_pid
);
156 printk("\n============================================\n");
157 printk( "[ BUG: circular locking deadlock detected! ]\n");
158 printk( "--------------------------------------------\n");
159 printk("%s/%d is deadlocking current task %s/%d\n\n",
160 task
->comm
, task
->pid
, current
->comm
, current
->pid
);
162 printk("\n1) %s/%d is trying to acquire this lock:\n",
163 current
->comm
, current
->pid
);
164 printk_lock(waiter
->lock
, 1);
166 printk("\n2) %s/%d is blocked on this lock:\n", task
->comm
, task
->pid
);
167 printk_lock(waiter
->deadlock_lock
, 1);
169 debug_show_held_locks(current
);
170 debug_show_held_locks(task
);
172 printk("\n%s/%d's [blocked] stackdump:\n\n", task
->comm
, task
->pid
);
173 show_stack(task
, NULL
);
174 printk("\n%s/%d's [current] stackdump:\n\n",
175 current
->comm
, current
->pid
);
177 debug_show_all_locks();
179 printk("[ turning off deadlock detection."
180 "Please report this trace. ]\n\n");
184 void debug_rt_mutex_lock(struct rt_mutex
*lock
)
188 void debug_rt_mutex_unlock(struct rt_mutex
*lock
)
190 TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock
) != current
);
194 debug_rt_mutex_proxy_lock(struct rt_mutex
*lock
, struct task_struct
*powner
)
198 void debug_rt_mutex_proxy_unlock(struct rt_mutex
*lock
)
200 TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock
));
203 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter
*waiter
)
205 memset(waiter
, 0x11, sizeof(*waiter
));
206 plist_node_init(&waiter
->list_entry
, MAX_PRIO
);
207 plist_node_init(&waiter
->pi_list_entry
, MAX_PRIO
);
210 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter
*waiter
)
212 TRACE_WARN_ON(!plist_node_empty(&waiter
->list_entry
));
213 TRACE_WARN_ON(!plist_node_empty(&waiter
->pi_list_entry
));
214 TRACE_WARN_ON(waiter
->task
);
215 memset(waiter
, 0x22, sizeof(*waiter
));
218 void debug_rt_mutex_init(struct rt_mutex
*lock
, const char *name
)
221 * Make sure we are not reinitializing a held lock:
223 debug_check_no_locks_freed((void *)lock
, sizeof(*lock
));
228 rt_mutex_deadlock_account_lock(struct rt_mutex
*lock
, struct task_struct
*task
)
232 void rt_mutex_deadlock_account_unlock(struct task_struct
*task
)