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authorIngo Molnar <mingo@elte.hu>2006-07-03 03:24:31 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-03 18:27:01 -0400
commitfb7e42413a098cc45b3adf858da290033af62bae (patch)
treeca8e9d46d0c16f7b3623caf42229c1c61b5a0026
parent36596243daf7e1d795c647de04af95e835b8c5b4 (diff)
[PATCH] lockdep: remove mutex deadlock checking code
With the lock validator we detect mutex deadlocks (and more), the mutex deadlock checking code is both redundant and slower. So remove it. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat
-rw-r--r--kernel/mutex-debug.c316
-rw-r--r--lib/Kconfig.debug8
2 files changed, 0 insertions, 324 deletions
diff --git a/kernel/mutex-debug.c b/kernel/mutex-debug.c
index fe0e9f2714d3..a92de145ed0d 100644
--- a/kernel/mutex-debug.c
+++ b/kernel/mutex-debug.c
@@ -51,321 +51,6 @@ LIST_HEAD(debug_mutex_held_locks);
51 */ 51 */
52int debug_mutex_on = 1; 52int debug_mutex_on = 1;
53 53
54static void printk_task(struct task_struct *p)
55{
56 if (p)
57 printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
58 else
59 printk("<none>");
60}
61
62static void printk_ti(struct thread_info *ti)
63{
64 if (ti)
65 printk_task(ti->task);
66 else
67 printk("<none>");
68}
69
70static void printk_task_short(struct task_struct *p)
71{
72 if (p)
73 printk("%s/%d [%p, %3d]", p->comm, p->pid, p, p->prio);
74 else
75 printk("<none>");
76}
77
78static void printk_lock(struct mutex *lock, int print_owner)
79{
80 printk(" [%p] {%s}\n", lock, lock->name);
81
82 if (print_owner && lock->owner) {
83 printk(".. held by: ");
84 printk_ti(lock->owner);
85 printk("\n");
86 }
87 if (lock->owner) {
88 printk("... acquired at: ");
89 print_symbol("%s\n", lock->acquire_ip);
90 }
91}
92
93/*
94 * printk locks held by a task:
95 */
96static void show_task_locks(struct task_struct *p)
97{
98 switch (p->state) {
99 case TASK_RUNNING: printk("R"); break;
100 case TASK_INTERRUPTIBLE: printk("S"); break;
101 case TASK_UNINTERRUPTIBLE: printk("D"); break;
102 case TASK_STOPPED: printk("T"); break;
103 case EXIT_ZOMBIE: printk("Z"); break;
104 case EXIT_DEAD: printk("X"); break;
105 default: printk("?"); break;
106 }
107 printk_task(p);
108 if (p->blocked_on) {
109 struct mutex *lock = p->blocked_on->lock;
110
111 printk(" blocked on mutex:");
112 printk_lock(lock, 1);
113 } else
114 printk(" (not blocked on mutex)\n");
115}
116
117/*
118 * printk all locks held in the system (if filter == NULL),
119 * or all locks belonging to a single task (if filter != NULL):
120 */
121void show_held_locks(struct task_struct *filter)
122{
123 struct list_head *curr, *cursor = NULL;
124 struct mutex *lock;
125 struct thread_info *t;
126 unsigned long flags;
127 int count = 0;
128
129 if (filter) {
130 printk("------------------------------\n");
131 printk("| showing all locks held by: | (");
132 printk_task_short(filter);
133 printk("):\n");
134 printk("------------------------------\n");
135 } else {
136 printk("---------------------------\n");
137 printk("| showing all locks held: |\n");
138 printk("---------------------------\n");
139 }
140
141 /*
142 * Play safe and acquire the global trace lock. We
143 * cannot printk with that lock held so we iterate
144 * very carefully:
145 */
146next:
147 debug_spin_lock_save(&debug_mutex_lock, flags);
148 list_for_each(curr, &debug_mutex_held_locks) {
149 if (cursor && curr != cursor)
150 continue;
151 lock = list_entry(curr, struct mutex, held_list);
152 t = lock->owner;
153 if (filter && (t != filter->thread_info))
154 continue;
155 count++;
156 cursor = curr->next;
157 debug_spin_unlock_restore(&debug_mutex_lock, flags);
158
159 printk("\n#%03d: ", count);
160 printk_lock(lock, filter ? 0 : 1);
161 goto next;
162 }
163 debug_spin_unlock_restore(&debug_mutex_lock, flags);
164 printk("\n");
165}
166
167void mutex_debug_show_all_locks(void)
168{
169 struct task_struct *g, *p;
170 int count = 10;
171 int unlock = 1;
172
173 printk("\nShowing all blocking locks in the system:\n");
174
175 /*
176 * Here we try to get the tasklist_lock as hard as possible,
177 * if not successful after 2 seconds we ignore it (but keep
178 * trying). This is to enable a debug printout even if a
179 * tasklist_lock-holding task deadlocks or crashes.
180 */
181retry:
182 if (!read_trylock(&tasklist_lock)) {
183 if (count == 10)
184 printk("hm, tasklist_lock locked, retrying... ");
185 if (count) {
186 count--;
187 printk(" #%d", 10-count);
188 mdelay(200);
189 goto retry;
190 }
191 printk(" ignoring it.\n");
192 unlock = 0;
193 }
194 if (count != 10)
195 printk(" locked it.\n");
196
197 do_each_thread(g, p) {
198 show_task_locks(p);
199 if (!unlock)
200 if (read_trylock(&tasklist_lock))
201 unlock = 1;
202 } while_each_thread(g, p);
203
204 printk("\n");
205 show_held_locks(NULL);
206 printk("=============================================\n\n");
207
208 if (unlock)
209 read_unlock(&tasklist_lock);
210}
211
212static void report_deadlock(struct task_struct *task, struct mutex *lock,
213 struct mutex *lockblk, unsigned long ip)
214{
215 printk("\n%s/%d is trying to acquire this lock:\n",
216 current->comm, current->pid);
217 printk_lock(lock, 1);
218 printk("... trying at: ");
219 print_symbol("%s\n", ip);
220 show_held_locks(current);
221
222 if (lockblk) {
223 printk("but %s/%d is deadlocking current task %s/%d!\n\n",
224 task->comm, task->pid, current->comm, current->pid);
225 printk("\n%s/%d is blocked on this lock:\n",
226 task->comm, task->pid);
227 printk_lock(lockblk, 1);
228
229 show_held_locks(task);
230
231 printk("\n%s/%d's [blocked] stackdump:\n\n",
232 task->comm, task->pid);
233 show_stack(task, NULL);
234 }
235
236 printk("\n%s/%d's [current] stackdump:\n\n",
237 current->comm, current->pid);
238 dump_stack();
239 mutex_debug_show_all_locks();
240 printk("[ turning off deadlock detection. Please report this. ]\n\n");
241 local_irq_disable();
242}
243
244/*
245 * Recursively check for mutex deadlocks:
246 */
247static int check_deadlock(struct mutex *lock, int depth,
248 struct thread_info *ti, unsigned long ip)
249{
250 struct mutex *lockblk;
251 struct task_struct *task;
252
253 if (!debug_mutex_on)
254 return 0;
255
256 ti = lock->owner;
257 if (!ti)
258 return 0;
259
260 task = ti->task;
261 lockblk = NULL;
262 if (task->blocked_on)
263 lockblk = task->blocked_on->lock;
264
265 /* Self-deadlock: */
266 if (current == task) {
267 DEBUG_OFF();
268 if (depth)
269 return 1;
270 printk("\n==========================================\n");
271 printk( "[ BUG: lock recursion deadlock detected! |\n");
272 printk( "------------------------------------------\n");
273 report_deadlock(task, lock, NULL, ip);
274 return 0;
275 }
276
277 /* Ugh, something corrupted the lock data structure? */
278 if (depth > 20) {
279 DEBUG_OFF();
280 printk("\n===========================================\n");
281 printk( "[ BUG: infinite lock dependency detected!? |\n");
282 printk( "-------------------------------------------\n");
283 report_deadlock(task, lock, lockblk, ip);
284 return 0;
285 }
286
287 /* Recursively check for dependencies: */
288 if (lockblk && check_deadlock(lockblk, depth+1, ti, ip)) {
289 printk("\n============================================\n");
290 printk( "[ BUG: circular locking deadlock detected! ]\n");
291 printk( "--------------------------------------------\n");
292 report_deadlock(task, lock, lockblk, ip);
293 return 0;
294 }
295 return 0;
296}
297
298/*
299 * Called when a task exits, this function checks whether the
300 * task is holding any locks, and reports the first one if so:
301 */
302void mutex_debug_check_no_locks_held(struct task_struct *task)
303{
304 struct list_head *curr, *next;
305 struct thread_info *t;
306 unsigned long flags;
307 struct mutex *lock;
308
309 if (!debug_mutex_on)
310 return;
311
312 debug_spin_lock_save(&debug_mutex_lock, flags);
313 list_for_each_safe(curr, next, &debug_mutex_held_locks) {
314 lock = list_entry(curr, struct mutex, held_list);
315 t = lock->owner;
316 if (t != task->thread_info)
317 continue;
318 list_del_init(curr);
319 DEBUG_OFF();
320 debug_spin_unlock_restore(&debug_mutex_lock, flags);
321
322 printk("BUG: %s/%d, lock held at task exit time!\n",
323 task->comm, task->pid);
324 printk_lock(lock, 1);
325 if (lock->owner != task->thread_info)
326 printk("exiting task is not even the owner??\n");
327 return;
328 }
329 debug_spin_unlock_restore(&debug_mutex_lock, flags);
330}
331
332/*
333 * Called when kernel memory is freed (or unmapped), or if a mutex
334 * is destroyed or reinitialized - this code checks whether there is
335 * any held lock in the memory range of <from> to <to>:
336 */
337void mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
338{
339 struct list_head *curr, *next;
340 const void *to = from + len;
341 unsigned long flags;
342 struct mutex *lock;
343 void *lock_addr;
344
345 if (!debug_mutex_on)
346 return;
347
348 debug_spin_lock_save(&debug_mutex_lock, flags);
349 list_for_each_safe(curr, next, &debug_mutex_held_locks) {
350 lock = list_entry(curr, struct mutex, held_list);
351 lock_addr = lock;
352 if (lock_addr < from || lock_addr >= to)
353 continue;
354 list_del_init(curr);
355 DEBUG_OFF();
356 debug_spin_unlock_restore(&debug_mutex_lock, flags);
357
358 printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
359 current->comm, current->pid, lock, from, to);
360 dump_stack();
361 printk_lock(lock, 1);
362 if (lock->owner != current_thread_info())
363 printk("freeing task is not even the owner??\n");
364 return;
365 }
366 debug_spin_unlock_restore(&debug_mutex_lock, flags);
367}
368
369/* 54/*
370 * Must be called with lock->wait_lock held. 55 * Must be called with lock->wait_lock held.
371 */ 56 */
@@ -405,7 +90,6 @@ void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
405 struct thread_info *ti __IP_DECL__) 90 struct thread_info *ti __IP_DECL__)
406{ 91{
407 SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock)); 92 SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
408 check_deadlock(lock, 0, ti, ip);
409 /* Mark the current thread as blocked on the lock: */ 93 /* Mark the current thread as blocked on the lock: */
410 ti->task->blocked_on = waiter; 94 ti->task->blocked_on = waiter;
411 waiter->lock = lock; 95 waiter->lock = lock;
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e4fcbd12cf6e..7b3863d4f5e8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -115,14 +115,6 @@ config DEBUG_PREEMPT
115 if kernel code uses it in a preemption-unsafe way. Also, the kernel 115 if kernel code uses it in a preemption-unsafe way. Also, the kernel
116 will detect preemption count underflows. 116 will detect preemption count underflows.
117 117
118config DEBUG_MUTEXES
119 bool "Mutex debugging, deadlock detection"
120 default n
121 depends on DEBUG_KERNEL
122 help
123 This allows mutex semantics violations and mutex related deadlocks
124 (lockups) to be detected and reported automatically.
125
126config DEBUG_RT_MUTEXES 118config DEBUG_RT_MUTEXES
127 bool "RT Mutex debugging, deadlock detection" 119 bool "RT Mutex debugging, deadlock detection"
128 depends on DEBUG_KERNEL && RT_MUTEXES 120 depends on DEBUG_KERNEL && RT_MUTEXES
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