[thirdparty/glibc.git] / nptl / pthread_mutex_lock.c

/* Copyright (C) 2002, 2003, 2004, 2005, 2006 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include "pthreadP.h"
#include <lowlevellock.h>


#ifndef LLL_MUTEX_LOCK
# define LLL_MUTEX_LOCK(mutex) lll_mutex_lock (mutex)
# define LLL_MUTEX_TRYLOCK(mutex) lll_mutex_trylock (mutex)
# define LLL_ROBUST_MUTEX_LOCK(mutex, id) lll_robust_mutex_lock (mutex, id)
#endif


int
__pthread_mutex_lock (mutex)
     pthread_mutex_t *mutex;
{
  assert (sizeof (mutex->__size) >= sizeof (mutex->__data));

  int oldval;
  pid_t id = THREAD_GETMEM (THREAD_SELF, tid);

  int retval = 0;
  switch (__builtin_expect (mutex->__data.__kind, PTHREAD_MUTEX_TIMED_NP))
    {
      /* Recursive mutex.  */
    case PTHREAD_MUTEX_RECURSIVE_NP:
      /* Check whether we already hold the mutex.  */
      if (mutex->__data.__owner == id)
	{
	  /* Just bump the counter.  */
	  if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
	    /* Overflow of the counter.  */
	    return EAGAIN;

	  ++mutex->__data.__count;

	  return 0;
	}

      /* We have to get the mutex.  */
      LLL_MUTEX_LOCK (mutex->__data.__lock);

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

      /* Error checking mutex.  */
    case PTHREAD_MUTEX_ERRORCHECK_NP:
      /* Check whether we already hold the mutex.  */
      if (__builtin_expect (mutex->__data.__owner == id, 0))
	return EDEADLK;

      /* FALLTHROUGH */

    case PTHREAD_MUTEX_TIMED_NP:
    simple:
      /* Normal mutex.  */
      LLL_MUTEX_LOCK (mutex->__data.__lock);
      assert (mutex->__data.__owner == 0);
      break;

    case PTHREAD_MUTEX_ADAPTIVE_NP:
      if (! __is_smp)
	goto simple;

      if (LLL_MUTEX_TRYLOCK (mutex->__data.__lock) != 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->__data.__lock);
		  break;
		}

#ifdef BUSY_WAIT_NOP
	      BUSY_WAIT_NOP;
#endif
	    }
	  while (LLL_MUTEX_TRYLOCK (mutex->__data.__lock) != 0);

	  mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
	}
      assert (mutex->__data.__owner == 0);
      break;

    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);

      oldval = mutex->__data.__lock;
      do
	{
	again:
	  if ((oldval & FUTEX_OWNER_DIED) != 0)
	    {
	      /* The previous owner died.  Try locking the mutex.  */
	      int newval = id;
#ifdef NO_INCR
	      newval |= FUTEX_WAITERS;
#endif

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

	      if (newval != oldval)
		{
		  oldval = newval;
		  goto again;
		}

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

	      ENQUEUE_MUTEX (mutex);
	      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 (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
	    {
	      if (mutex->__data.__kind
		  == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
		{
		  THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
				 NULL);
		  return EDEADLK;
		}

	      if (mutex->__data.__kind
		  == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
		{
		  THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
				 NULL);

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

		  ++mutex->__data.__count;

		  return 0;
		}
	    }

	  oldval = LLL_ROBUST_MUTEX_LOCK (mutex->__data.__lock, id);

	  if (__builtin_expect (mutex->__data.__owner
				== PTHREAD_MUTEX_NOTRECOVERABLE, 0))
	    {
	      /* This mutex is now not recoverable.  */
	      mutex->__data.__count = 0;
	      lll_mutex_unlock (mutex->__data.__lock);
	      THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
	      return ENOTRECOVERABLE;
	    }
	}
      while ((oldval & FUTEX_OWNER_DIED) != 0);

      mutex->__data.__count = 1;
      ENQUEUE_MUTEX (mutex);
      THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
      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

  return retval;
}
#ifndef __pthread_mutex_lock
strong_alias (__pthread_mutex_lock, pthread_mutex_lock)
strong_alias (__pthread_mutex_lock, __pthread_mutex_lock_internal)
#endif
Commit	Line	Data
683040c3	1	/* Copyright (C) 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
76a50749 UD	2	This file is part of the GNU C Library.
	3	Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
	9
	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	Lesser General Public License for more details.
	14
	15	You should have received a copy of the GNU Lesser General Public
	16	License along with the GNU C Library; if not, write to the Free
	17	Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
	18	02111-1307 USA. */
	19
3892d906	20	#include <assert.h>
76a50749	21	#include <errno.h>
1bcfb5a5	22	#include <stdlib.h>
76a50749 UD	23	#include "pthreadP.h"
	24	#include <lowlevellock.h>
	25
	26
69431c9a UD	27	#ifndef LLL_MUTEX_LOCK
69431c9a UD	28	# define LLL_MUTEX_LOCK(mutex) lll_mutex_lock (mutex)
2c0b891a	29	# define LLL_MUTEX_TRYLOCK(mutex) lll_mutex_trylock (mutex)
683040c3	30	# define LLL_ROBUST_MUTEX_LOCK(mutex, id) lll_robust_mutex_lock (mutex, id)
69431c9a UD	31	#endif
	32
	33
76a50749 UD	34	int
	35	__pthread_mutex_lock (mutex)
	36	pthread_mutex_t *mutex;
	37	{
2c0b891a UD	38	assert (sizeof (mutex->__size) >= sizeof (mutex->__data));
2c0b891a UD	39
683040c3	40	int oldval;
61623643	41	pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
76a50749	42
1bcfb5a5	43	int retval = 0;
76a50749 UD	44	switch (__builtin_expect (mutex->__data.__kind, PTHREAD_MUTEX_TIMED_NP))
	45	{
	46	/* Recursive mutex. */
	47	case PTHREAD_MUTEX_RECURSIVE_NP:
	48	/* Check whether we already hold the mutex. */
9a7178d6	49	if (mutex->__data.__owner == id)
76a50749 UD	50	{
	51	/* Just bump the counter. */
	52	if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
	53	/* Overflow of the counter. */
	54	return EAGAIN;
	55
	56	++mutex->__data.__count;
76a50749	57
3892d906	58	return 0;
76a50749	59	}
3892d906 UD	60
	61	/* We have to get the mutex. */
	62	LLL_MUTEX_LOCK (mutex->__data.__lock);
	63
1bcfb5a5	64	assert (mutex->__data.__owner == 0);
3892d906	65	mutex->__data.__count = 1;
76a50749 UD	66	break;
	67
	68	/* Error checking mutex. */
	69	case PTHREAD_MUTEX_ERRORCHECK_NP:
	70	/* Check whether we already hold the mutex. */
1bcfb5a5	71	if (__builtin_expect (mutex->__data.__owner == id, 0))
76a50749 UD	72	return EDEADLK;
	73
	74	/* FALLTHROUGH */
	75
76a50749	76	case PTHREAD_MUTEX_TIMED_NP:
2c0b891a	77	simple:
76a50749	78	/* Normal mutex. */
69431c9a	79	LLL_MUTEX_LOCK (mutex->__data.__lock);
1bcfb5a5	80	assert (mutex->__data.__owner == 0);
76a50749	81	break;
2c0b891a UD	82
	83	case PTHREAD_MUTEX_ADAPTIVE_NP:
	84	if (! __is_smp)
	85	goto simple;
	86
	87	if (LLL_MUTEX_TRYLOCK (mutex->__data.__lock) != 0)
	88	{
	89	int cnt = 0;
	90	int max_cnt = MIN (MAX_ADAPTIVE_COUNT,
	91	mutex->__data.__spins * 2 + 10);
	92	do
	93	{
	94	if (cnt++ >= max_cnt)
	95	{
	96	LLL_MUTEX_LOCK (mutex->__data.__lock);
	97	break;
	98	}
	99
	100	#ifdef BUSY_WAIT_NOP
	101	BUSY_WAIT_NOP;
	102	#endif
	103	}
	104	while (LLL_MUTEX_TRYLOCK (mutex->__data.__lock) != 0);
	105
	106	mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
	107	}
1bcfb5a5 UD	108	assert (mutex->__data.__owner == 0);
	109	break;
	110
0f6699ea UD	111	case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
	112	case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
	113	case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
	114	case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
	115	THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
	116	&mutex->__data.__list.__next);
	117
683040c3 UD	118	oldval = mutex->__data.__lock;
683040c3 UD	119	do
1bcfb5a5	120	{
0f6699ea	121	again:
683040c3 UD	122	if ((oldval & FUTEX_OWNER_DIED) != 0)
	123	{
	124	/* The previous owner died. Try locking the mutex. */
0f6699ea UD	125	int newval = id;
	126	#ifdef NO_INCR
	127	newval \|= FUTEX_WAITERS;
	128	#endif
	129
	130	newval
	131	= atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
	132	newval, oldval);
	133
	134	if (newval != oldval)
683040c3	135	{
683040c3	136	oldval = newval;
0f6699ea	137	goto again;
683040c3	138	}
1bcfb5a5	139
683040c3 UD	140	/* We got the mutex. */
	141	mutex->__data.__count = 1;
	142	/* But it is inconsistent unless marked otherwise. */
	143	mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
	144
	145	ENQUEUE_MUTEX (mutex);
0f6699ea	146	THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
683040c3 UD	147
	148	/* Note that we deliberately exit here. If we fall
	149	through to the end of the function __nusers would be
	150	incremented which is not correct because the old
	151	owner has to be discounted. If we are not supposed
	152	to increment __nusers we actually have to decrement
	153	it here. */
	154	#ifdef NO_INCR
	155	--mutex->__data.__nusers;
	156	#endif
1bcfb5a5	157
683040c3 UD	158	return EOWNERDEAD;
683040c3 UD	159	}
1bcfb5a5	160
683040c3	161	/* Check whether we already hold the mutex. */
0f6699ea	162	if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
683040c3 UD	163	{
683040c3 UD	164	if (mutex->__data.__kind
0f6699ea UD	165	== PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
	166	{
	167	THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
	168	NULL);
	169	return EDEADLK;
	170	}
1bcfb5a5	171
683040c3	172	if (mutex->__data.__kind
0f6699ea	173	== PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
683040c3	174	{
0f6699ea UD	175	THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
	176	NULL);
	177
683040c3 UD	178	/* Just bump the counter. */
	179	if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
	180	/* Overflow of the counter. */
	181	return EAGAIN;
1bcfb5a5	182
683040c3	183	++mutex->__data.__count;
1bcfb5a5	184
683040c3 UD	185	return 0;
	186	}
	187	}
1bcfb5a5	188
683040c3	189	oldval = LLL_ROBUST_MUTEX_LOCK (mutex->__data.__lock, id);
1bcfb5a5	190
683040c3 UD	191	if (__builtin_expect (mutex->__data.__owner
	192	== PTHREAD_MUTEX_NOTRECOVERABLE, 0))
	193	{
	194	/* This mutex is now not recoverable. */
	195	mutex->__data.__count = 0;
	196	lll_mutex_unlock (mutex->__data.__lock);
0f6699ea	197	THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
683040c3 UD	198	return ENOTRECOVERABLE;
683040c3 UD	199	}
1bcfb5a5	200	}
683040c3	201	while ((oldval & FUTEX_OWNER_DIED) != 0);
1bcfb5a5	202
683040c3	203	mutex->__data.__count = 1;
1bcfb5a5	204	ENQUEUE_MUTEX (mutex);
0f6699ea	205	THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
2c0b891a	206	break;
dcc73a8d UD	207
	208	default:
	209	/* Correct code cannot set any other type. */
	210	return EINVAL;
76a50749 UD	211	}
76a50749 UD	212
3892d906	213	/* Record the ownership. */
3892d906 UD	214	mutex->__data.__owner = id;
	215	#ifndef NO_INCR
	216	++mutex->__data.__nusers;
	217	#endif
	218
1bcfb5a5	219	return retval;
76a50749	220	}
69431c9a	221	#ifndef __pthread_mutex_lock
76a50749	222	strong_alias (__pthread_mutex_lock, pthread_mutex_lock)
db0a052c	223	strong_alias (__pthread_mutex_lock, __pthread_mutex_lock_internal)
69431c9a	224	#endif