about summary refs log tree commit diff
path: root/nptl/pthread_mutex_lock.c
blob: 7858abd5282db55f96e4d38c4af72278f1ee2a22 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
/* Copyright (C) 2002-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/param.h>
#include <not-cancel.h>
#include "pthreadP.h"
#include <atomic.h>
#include <futex-internal.h>
#include <stap-probe.h>

#ifndef lll_lock_elision
#define lll_lock_elision(lock, try_lock, private)	({ \
      lll_lock (lock, private); 0; })
#endif

#ifndef lll_trylock_elision
#define lll_trylock_elision(a,t) lll_trylock(a)
#endif

/* Some of the following definitions differ when pthread_mutex_cond_lock.c
   includes this file.  */
#ifndef LLL_MUTEX_LOCK
# define LLL_MUTEX_LOCK(mutex) \
  lll_lock ((mutex)->__data.__lock, PTHREAD_MUTEX_PSHARED (mutex))
# define LLL_MUTEX_TRYLOCK(mutex) \
  lll_trylock ((mutex)->__data.__lock)
# define LLL_ROBUST_MUTEX_LOCK_MODIFIER 0
# define LLL_MUTEX_LOCK_ELISION(mutex) \
  lll_lock_elision ((mutex)->__data.__lock, (mutex)->__data.__elision, \
		   PTHREAD_MUTEX_PSHARED (mutex))
# define LLL_MUTEX_TRYLOCK_ELISION(mutex) \
  lll_trylock_elision((mutex)->__data.__lock, (mutex)->__data.__elision, \
		   PTHREAD_MUTEX_PSHARED (mutex))
#endif

#ifndef FORCE_ELISION
#define FORCE_ELISION(m, s)
#endif

static int __pthread_mutex_lock_full (pthread_mutex_t *mutex)
     __attribute_noinline__;

int
__pthread_mutex_lock (pthread_mutex_t *mutex)
{
  /* See concurrency notes regarding mutex type which is loaded from __kind
     in struct __pthread_mutex_s in sysdeps/nptl/bits/thread-shared-types.h.  */
  unsigned int type = PTHREAD_MUTEX_TYPE_ELISION (mutex);

  LIBC_PROBE (mutex_entry, 1, mutex);

  if (__builtin_expect (type & ~(PTHREAD_MUTEX_KIND_MASK_NP
				 | PTHREAD_MUTEX_ELISION_FLAGS_NP), 0))
    return __pthread_mutex_lock_full (mutex);

  if (__glibc_likely (type == PTHREAD_MUTEX_TIMED_NP))
    {
      FORCE_ELISION (mutex, goto elision);
    simple:
      /* Normal mutex.  */
      LLL_MUTEX_LOCK (mutex);
      assert (mutex->__data.__owner == 0);
    }
#ifdef HAVE_ELISION
  else if (__glibc_likely (type == PTHREAD_MUTEX_TIMED_ELISION_NP))
    {
  elision: __attribute__((unused))
      /* This case can never happen on a system without elision,
         as the mutex type initialization functions will not
	 allow to set the elision flags.  */
      /* Don't record owner or users for elision case.  This is a
         tail call.  */
      return LLL_MUTEX_LOCK_ELISION (mutex);
    }
#endif
  else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex)
			     == PTHREAD_MUTEX_RECURSIVE_NP, 1))
    {
      /* Recursive mutex.  */
      pid_t id = THREAD_GETMEM (THREAD_SELF, tid);

      /* Check whether we already hold the mutex.  */
      if (mutex->__data.__owner == id)
	{
	  /* Just bump the counter.  */
	  if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
	    /* Overflow of the counter.  */
	    return EAGAIN;

	  ++mutex->__data.__count;

	  return 0;
	}

      /* We have to get the mutex.  */
      LLL_MUTEX_LOCK (mutex);

      assert (mutex->__data.__owner == 0);
      mutex->__data.__count = 1;
    }
  else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex)
			  == PTHREAD_MUTEX_ADAPTIVE_NP, 1))
    {
      if (! __is_smp)
	goto simple;

      if (LLL_MUTEX_TRYLOCK (mutex) != 0)
	{
	  int cnt = 0;
	  int max_cnt = MIN (max_adaptive_count (),
			     mutex->__data.__spins * 2 + 10);
	  do
	    {
	      if (cnt++ >= max_cnt)
		{
		  LLL_MUTEX_LOCK (mutex);
		  break;
		}
	      atomic_spin_nop ();
	    }
	  while (LLL_MUTEX_TRYLOCK (mutex) != 0);

	  mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
	}
      assert (mutex->__data.__owner == 0);
    }
  else
    {
      pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
      assert (PTHREAD_MUTEX_TYPE (mutex) == PTHREAD_MUTEX_ERRORCHECK_NP);
      /* Check whether we already hold the mutex.  */
      if (__glibc_unlikely (mutex->__data.__owner == id))
	return EDEADLK;
      goto simple;
    }

  pid_t id = THREAD_GETMEM (THREAD_SELF, tid);

  /* Record the ownership.  */
  mutex->__data.__owner = id;
#ifndef NO_INCR
  ++mutex->__data.__nusers;
#endif

  LIBC_PROBE (mutex_acquired, 1, mutex);

  return 0;
}

static int
__pthread_mutex_lock_full (pthread_mutex_t *mutex)
{
  int oldval;
  pid_t id = THREAD_GETMEM (THREAD_SELF, tid);

  switch (PTHREAD_MUTEX_TYPE (mutex))
    {
    case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
    case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
    case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
    case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
      THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
		     &mutex->__data.__list.__next);
      /* We need to set op_pending before starting the operation.  Also
	 see comments at ENQUEUE_MUTEX.  */
      __asm ("" ::: "memory");

      oldval = mutex->__data.__lock;
      /* This is set to FUTEX_WAITERS iff we might have shared the
	 FUTEX_WAITERS flag with other threads, and therefore need to keep it
	 set to avoid lost wake-ups.  We have the same requirement in the
	 simple mutex algorithm.
	 We start with value zero for a normal mutex, and FUTEX_WAITERS if we
	 are building the special case mutexes for use from within condition
	 variables.  */
      unsigned int assume_other_futex_waiters = LLL_ROBUST_MUTEX_LOCK_MODIFIER;
      while (1)
	{
	  /* Try to acquire the lock through a CAS from 0 (not acquired) to
	     our TID | assume_other_futex_waiters.  */
	  if (__glibc_likely (oldval == 0))
	    {
	      oldval
	        = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
	            id | assume_other_futex_waiters, 0);
	      if (__glibc_likely (oldval == 0))
		break;
	    }

	  if ((oldval & FUTEX_OWNER_DIED) != 0)
	    {
	      /* The previous owner died.  Try locking the mutex.  */
	      int newval = id;
#ifdef NO_INCR
	      /* We are not taking assume_other_futex_waiters into accoount
		 here simply because we'll set FUTEX_WAITERS anyway.  */
	      newval |= FUTEX_WAITERS;
#else
	      newval |= (oldval & FUTEX_WAITERS) | assume_other_futex_waiters;
#endif

	      newval
		= atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
						       newval, oldval);

	      if (newval != oldval)
		{
		  oldval = newval;
		  continue;
		}

	      /* We got the mutex.  */
	      mutex->__data.__count = 1;
	      /* But it is inconsistent unless marked otherwise.  */
	      mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;

	      /* We must not enqueue the mutex before we have acquired it.
		 Also see comments at ENQUEUE_MUTEX.  */
	      __asm ("" ::: "memory");
	      ENQUEUE_MUTEX (mutex);
	      /* We need to clear op_pending after we enqueue the mutex.  */
	      __asm ("" ::: "memory");
	      THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);

	      /* Note that we deliberately exit here.  If we fall
		 through to the end of the function __nusers would be
		 incremented which is not correct because the old
		 owner has to be discounted.  If we are not supposed
		 to increment __nusers we actually have to decrement
		 it here.  */
#ifdef NO_INCR
	      --mutex->__data.__nusers;
#endif

	      return EOWNERDEAD;
	    }

	  /* Check whether we already hold the mutex.  */
	  if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
	    {
	      int kind = PTHREAD_MUTEX_TYPE (mutex);
	      if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
		{
		  /* We do not need to ensure ordering wrt another memory
		     access.  Also see comments at ENQUEUE_MUTEX. */
		  THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
				 NULL);
		  return EDEADLK;
		}

	      if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
		{
		  /* We do not need to ensure ordering wrt another memory
		     access.  */
		  THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
				 NULL);

		  /* Just bump the counter.  */
		  if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
		    /* Overflow of the counter.  */
		    return EAGAIN;

		  ++mutex->__data.__count;

		  return 0;
		}
	    }

	  /* We cannot acquire the mutex nor has its owner died.  Thus, try
	     to block using futexes.  Set FUTEX_WAITERS if necessary so that
	     other threads are aware that there are potentially threads
	     blocked on the futex.  Restart if oldval changed in the
	     meantime.  */
	  if ((oldval & FUTEX_WAITERS) == 0)
	    {
	      if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
							oldval | FUTEX_WAITERS,
							oldval)
		  != 0)
		{
		  oldval = mutex->__data.__lock;
		  continue;
		}
	      oldval |= FUTEX_WAITERS;
	    }

	  /* It is now possible that we share the FUTEX_WAITERS flag with
	     another thread; therefore, update assume_other_futex_waiters so
	     that we do not forget about this when handling other cases
	     above and thus do not cause lost wake-ups.  */
	  assume_other_futex_waiters |= FUTEX_WAITERS;

	  /* Block using the futex and reload current lock value.  */
	  lll_futex_wait (&mutex->__data.__lock, oldval,
			  PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
	  oldval = mutex->__data.__lock;
	}

      /* We have acquired the mutex; check if it is still consistent.  */
      if (__builtin_expect (mutex->__data.__owner
			    == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
	{
	  /* This mutex is now not recoverable.  */
	  mutex->__data.__count = 0;
	  int private = PTHREAD_ROBUST_MUTEX_PSHARED (mutex);
	  lll_unlock (mutex->__data.__lock, private);
	  /* FIXME This violates the mutex destruction requirements.  See
	     __pthread_mutex_unlock_full.  */
	  THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
	  return ENOTRECOVERABLE;
	}

      mutex->__data.__count = 1;
      /* We must not enqueue the mutex before we have acquired it.
	 Also see comments at ENQUEUE_MUTEX.  */
      __asm ("" ::: "memory");
      ENQUEUE_MUTEX (mutex);
      /* We need to clear op_pending after we enqueue the mutex.  */
      __asm ("" ::: "memory");
      THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
      break;

    /* The PI support requires the Linux futex system call.  If that's not
       available, pthread_mutex_init should never have allowed the type to
       be set.  So it will get the default case for an invalid type.  */
#ifdef __NR_futex
    case PTHREAD_MUTEX_PI_RECURSIVE_NP:
    case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
    case PTHREAD_MUTEX_PI_NORMAL_NP:
    case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
    case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
    case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
    case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
    case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
      {
	int kind, robust;
	{
	  /* See concurrency notes regarding __kind in struct __pthread_mutex_s
	     in sysdeps/nptl/bits/thread-shared-types.h.  */
	  int mutex_kind = atomic_load_relaxed (&(mutex->__data.__kind));
	  kind = mutex_kind & PTHREAD_MUTEX_KIND_MASK_NP;
	  robust = mutex_kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
	}

	if (robust)
	  {
	    /* Note: robust PI futexes are signaled by setting bit 0.  */
	    THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
			   (void *) (((uintptr_t) &mutex->__data.__list.__next)
				     | 1));
	    /* We need to set op_pending before starting the operation.  Also
	       see comments at ENQUEUE_MUTEX.  */
	    __asm ("" ::: "memory");
	  }

	oldval = mutex->__data.__lock;

	/* Check whether we already hold the mutex.  */
	if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
	  {
	    if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
	      {
		/* We do not need to ensure ordering wrt another memory
		   access.  */
		THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
		return EDEADLK;
	      }

	    if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
	      {
		/* We do not need to ensure ordering wrt another memory
		   access.  */
		THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);

		/* Just bump the counter.  */
		if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
		  /* Overflow of the counter.  */
		  return EAGAIN;

		++mutex->__data.__count;

		return 0;
	      }
	  }

	int newval = id;
# ifdef NO_INCR
	newval |= FUTEX_WAITERS;
# endif
	oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
						      newval, 0);

	if (oldval != 0)
	  {
	    /* The mutex is locked.  The kernel will now take care of
	       everything.  */
	    int private = (robust
			   ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
			   : PTHREAD_MUTEX_PSHARED (mutex));
	    int e = futex_lock_pi ((unsigned int *) &mutex->__data.__lock,
				   NULL, private);
	    if (e == ESRCH || e == EDEADLK)
	      {
		assert (e != EDEADLK
			|| (kind != PTHREAD_MUTEX_ERRORCHECK_NP
			    && kind != PTHREAD_MUTEX_RECURSIVE_NP));
		/* ESRCH can happen only for non-robust PI mutexes where
		   the owner of the lock died.  */
		assert (e != ESRCH || !robust);

		/* Delay the thread indefinitely.  */
		while (1)
		  lll_timedwait (&(int){0}, 0, 0 /* ignored */, NULL,
				 private);
	      }

	    oldval = mutex->__data.__lock;

	    assert (robust || (oldval & FUTEX_OWNER_DIED) == 0);
	  }

	if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
	  {
	    atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);

	    /* We got the mutex.  */
	    mutex->__data.__count = 1;
	    /* But it is inconsistent unless marked otherwise.  */
	    mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;

	    /* We must not enqueue the mutex before we have acquired it.
	       Also see comments at ENQUEUE_MUTEX.  */
	    __asm ("" ::: "memory");
	    ENQUEUE_MUTEX_PI (mutex);
	    /* We need to clear op_pending after we enqueue the mutex.  */
	    __asm ("" ::: "memory");
	    THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);

	    /* Note that we deliberately exit here.  If we fall
	       through to the end of the function __nusers would be
	       incremented which is not correct because the old owner
	       has to be discounted.  If we are not supposed to
	       increment __nusers we actually have to decrement it here.  */
# ifdef NO_INCR
	    --mutex->__data.__nusers;
# endif

	    return EOWNERDEAD;
	  }

	if (robust
	    && __builtin_expect (mutex->__data.__owner
				 == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
	  {
	    /* This mutex is now not recoverable.  */
	    mutex->__data.__count = 0;

	    futex_unlock_pi ((unsigned int *) &mutex->__data.__lock,
			     PTHREAD_ROBUST_MUTEX_PSHARED (mutex));

	    /* To the kernel, this will be visible after the kernel has
	       acquired the mutex in the syscall.  */
	    THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
	    return ENOTRECOVERABLE;
	  }

	mutex->__data.__count = 1;
	if (robust)
	  {
	    /* We must not enqueue the mutex before we have acquired it.
	       Also see comments at ENQUEUE_MUTEX.  */
	    __asm ("" ::: "memory");
	    ENQUEUE_MUTEX_PI (mutex);
	    /* We need to clear op_pending after we enqueue the mutex.  */
	    __asm ("" ::: "memory");
	    THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
	  }
      }
      break;
#endif  /* __NR_futex.  */

    case PTHREAD_MUTEX_PP_RECURSIVE_NP:
    case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
    case PTHREAD_MUTEX_PP_NORMAL_NP:
    case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
      {
	/* See concurrency notes regarding __kind in struct __pthread_mutex_s
	   in sysdeps/nptl/bits/thread-shared-types.h.  */
	int kind = atomic_load_relaxed (&(mutex->__data.__kind))
	  & PTHREAD_MUTEX_KIND_MASK_NP;

	oldval = mutex->__data.__lock;

	/* Check whether we already hold the mutex.  */
	if (mutex->__data.__owner == id)
	  {
	    if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
	      return EDEADLK;

	    if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
	      {
		/* Just bump the counter.  */
		if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
		  /* Overflow of the counter.  */
		  return EAGAIN;

		++mutex->__data.__count;

		return 0;
	      }
	  }

	int oldprio = -1, ceilval;
	do
	  {
	    int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
			  >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;

	    if (__pthread_current_priority () > ceiling)
	      {
		if (oldprio != -1)
		  __pthread_tpp_change_priority (oldprio, -1);
		return EINVAL;
	      }

	    int retval = __pthread_tpp_change_priority (oldprio, ceiling);
	    if (retval)
	      return retval;

	    ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
	    oldprio = ceiling;

	    oldval
	      = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
#ifdef NO_INCR
						     ceilval | 2,
#else
						     ceilval | 1,
#endif
						     ceilval);

	    if (oldval == ceilval)
	      break;

	    do
	      {
		oldval
		  = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
							 ceilval | 2,
							 ceilval | 1);

		if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval)
		  break;

		if (oldval != ceilval)
		  lll_futex_wait (&mutex->__data.__lock, ceilval | 2,
				  PTHREAD_MUTEX_PSHARED (mutex));
	      }
	    while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
							ceilval | 2, ceilval)
		   != ceilval);
	  }
	while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);

	assert (mutex->__data.__owner == 0);
	mutex->__data.__count = 1;
      }
      break;

    default:
      /* Correct code cannot set any other type.  */
      return EINVAL;
    }

  /* Record the ownership.  */
  mutex->__data.__owner = id;
#ifndef NO_INCR
  ++mutex->__data.__nusers;
#endif

  LIBC_PROBE (mutex_acquired, 1, mutex);

  return 0;
}
#ifndef __pthread_mutex_lock
weak_alias (__pthread_mutex_lock, pthread_mutex_lock)
hidden_def (__pthread_mutex_lock)
#endif


#ifdef NO_INCR
void
__pthread_mutex_cond_lock_adjust (pthread_mutex_t *mutex)
{
  /* See concurrency notes regarding __kind in struct __pthread_mutex_s
     in sysdeps/nptl/bits/thread-shared-types.h.  */
  int mutex_kind = atomic_load_relaxed (&(mutex->__data.__kind));
  assert ((mutex_kind & PTHREAD_MUTEX_PRIO_INHERIT_NP) != 0);
  assert ((mutex_kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) == 0);
  assert ((mutex_kind & PTHREAD_MUTEX_PSHARED_BIT) == 0);

  /* Record the ownership.  */
  pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
  mutex->__data.__owner = id;

  if (mutex_kind == PTHREAD_MUTEX_PI_RECURSIVE_NP)
    ++mutex->__data.__count;
}
#endif