nptl/pthread_mutex_unlock.c

   1 /* Copyright (C) 2002, 2003, 2005-2007, 2008 Free Software Foundation, Inc.
   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
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include "pthreadP.h"
  23 #include <lowlevellock.h>
  24
  25
  26 int
  27 internal_function attribute_hidden
  28 __pthread_mutex_unlock_usercnt (mutex, decr)
  29      pthread_mutex_t *mutex;
  30      int decr;
  31 {
  32   int newowner = 0;
  33
  34   switch (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex),
  35                             PTHREAD_MUTEX_TIMED_NP))
  36     {
  37     case PTHREAD_MUTEX_RECURSIVE_NP:
  38       /* Recursive mutex.  */
  39       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
  40         return EPERM;
  41
  42       if (--mutex->__data.__count != 0)
  43         /* We still hold the mutex.  */
  44         return 0;
  45       goto normal;
  46
  47     case PTHREAD_MUTEX_ERRORCHECK_NP:
  48       /* Error checking mutex.  */
  49       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)
  50           || ! lll_islocked (mutex->__data.__lock))
  51         return EPERM;
  52       /* FALLTHROUGH */
  53
  54     case PTHREAD_MUTEX_TIMED_NP:
  55     case PTHREAD_MUTEX_ADAPTIVE_NP:
  56       /* Always reset the owner field.  */
  57     normal:
  58       mutex->__data.__owner = 0;
  59       if (decr)
  60         /* One less user.  */
  61         --mutex->__data.__nusers;
  62
  63       /* Unlock.  */
  64       lll_unlock (mutex->__data.__lock, PTHREAD_MUTEX_PSHARED (mutex));
  65       break;
  66
  67     case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
  68       /* Recursive mutex.  */
  69       if ((mutex->__data.__lock & FUTEX_TID_MASK)
  70           == THREAD_GETMEM (THREAD_SELF, tid)
  71           && __builtin_expect (mutex->__data.__owner
  72                                == PTHREAD_MUTEX_INCONSISTENT, 0))
  73         {
  74           if (--mutex->__data.__count != 0)
  75             /* We still hold the mutex.  */
  76             return ENOTRECOVERABLE;
  77
  78           goto notrecoverable;
  79         }
  80
  81       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
  82         return EPERM;
  83
  84       if (--mutex->__data.__count != 0)
  85         /* We still hold the mutex.  */
  86         return 0;
  87
  88       goto robust;
  89
  90     case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
  91     case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
  92     case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
  93       if ((mutex->__data.__lock & FUTEX_TID_MASK)
  94           != THREAD_GETMEM (THREAD_SELF, tid)
  95           || ! lll_islocked (mutex->__data.__lock))
  96         return EPERM;
  97
  98       /* If the previous owner died and the caller did not succeed in
  99          making the state consistent, mark the mutex as unrecoverable
 100          and make all waiters.  */
 101       if (__builtin_expect (mutex->__data.__owner
 102                             == PTHREAD_MUTEX_INCONSISTENT, 0))
 103       notrecoverable:
 104         newowner = PTHREAD_MUTEX_NOTRECOVERABLE;
 105
 106     robust:
 107       /* Remove mutex from the list.  */
 108       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 109                      &mutex->__data.__list.__next);
 110       DEQUEUE_MUTEX (mutex);
 111
 112       mutex->__data.__owner = newowner;
 113       if (decr)
 114         /* One less user.  */
 115         --mutex->__data.__nusers;
 116
 117       /* Unlock.  */
 118       lll_robust_unlock (mutex->__data.__lock,
 119                          PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 120
 121       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 122       break;
 123
 124     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 125       /* Recursive mutex.  */
 126       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 127         return EPERM;
 128
 129       if (--mutex->__data.__count != 0)
 130         /* We still hold the mutex.  */
 131         return 0;
 132       goto continue_pi;
 133
 134     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 135       /* Recursive mutex.  */
 136       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 137           == THREAD_GETMEM (THREAD_SELF, tid)
 138           && __builtin_expect (mutex->__data.__owner
 139                                == PTHREAD_MUTEX_INCONSISTENT, 0))
 140         {
 141           if (--mutex->__data.__count != 0)
 142             /* We still hold the mutex.  */
 143             return ENOTRECOVERABLE;
 144
 145           goto pi_notrecoverable;
 146         }
 147
 148       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 149         return EPERM;
 150
 151       if (--mutex->__data.__count != 0)
 152         /* We still hold the mutex.  */
 153         return 0;
 154
 155       goto continue_pi;
 156
 157     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 158     case PTHREAD_MUTEX_PI_NORMAL_NP:
 159     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 160     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 161     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 162     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 163       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 164           != THREAD_GETMEM (THREAD_SELF, tid)
 165           || ! lll_islocked (mutex->__data.__lock))
 166         return EPERM;
 167
 168       /* If the previous owner died and the caller did not succeed in
 169          making the state consistent, mark the mutex as unrecoverable
 170          and make all waiters.  */
 171       if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0
 172           && __builtin_expect (mutex->__data.__owner
 173                                == PTHREAD_MUTEX_INCONSISTENT, 0))
 174       pi_notrecoverable:
 175        newowner = PTHREAD_MUTEX_NOTRECOVERABLE;
 176
 177     continue_pi:
 178       if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0)
 179         {
 180           /* Remove mutex from the list.
 181              Note: robust PI futexes are signaled by setting bit 0.  */
 182           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 183                          (void *) (((uintptr_t) &mutex->__data.__list.__next)
 184                                    | 1));
 185           DEQUEUE_MUTEX (mutex);
 186         }
 187
 188       mutex->__data.__owner = newowner;
 189       if (decr)
 190         /* One less user.  */
 191         --mutex->__data.__nusers;
 192
 193       /* Unlock.  */
 194       if ((mutex->__data.__lock & FUTEX_WAITERS) != 0
 195           || atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock, 0,
 196                                                    THREAD_GETMEM (THREAD_SELF,
 197                                                                   tid)))
 198         {
 199           int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 200           int private = (robust
 201                          ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
 202                          : PTHREAD_MUTEX_PSHARED (mutex));
 203           INTERNAL_SYSCALL_DECL (__err);
 204           INTERNAL_SYSCALL (futex, __err, 2, &mutex->__data.__lock,
 205                             __lll_private_flag (FUTEX_UNLOCK_PI, private));
 206         }
 207
 208       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 209       break;
 210
 211     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 212       /* Recursive mutex.  */
 213       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 214         return EPERM;
 215
 216       if (--mutex->__data.__count != 0)
 217         /* We still hold the mutex.  */
 218         return 0;
 219       goto pp;
 220
 221     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 222       /* Error checking mutex.  */
 223       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)
 224           || (mutex->__data.__lock & ~ PTHREAD_MUTEX_PRIO_CEILING_MASK) == 0)
 225         return EPERM;
 226       /* FALLTHROUGH */
 227
 228     case PTHREAD_MUTEX_PP_NORMAL_NP:
 229     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 230       /* Always reset the owner field.  */
 231     pp:
 232       mutex->__data.__owner = 0;
 233
 234       if (decr)
 235         /* One less user.  */
 236         --mutex->__data.__nusers;
 237
 238       /* Unlock.  */
 239       int newval, oldval;
 240       do
 241         {
 242           oldval = mutex->__data.__lock;
 243           newval = oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK;
 244         }
 245       while (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
 246                                                    newval, oldval));
 247
 248       if ((oldval & ~PTHREAD_MUTEX_PRIO_CEILING_MASK) > 1)
 249         lll_futex_wake (&mutex->__data.__lock, 1,
 250                         PTHREAD_MUTEX_PSHARED (mutex));
 251
 252       int oldprio = newval >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 253       return __pthread_tpp_change_priority (oldprio, -1);
 254
 255     default:
 256       /* Correct code cannot set any other type.  */
 257       return EINVAL;
 258     }
 259
 260   return 0;
 261 }
 262
 263
 264 int
 265 __pthread_mutex_unlock (mutex)
 266      pthread_mutex_t *mutex;
 267 {
 268   return __pthread_mutex_unlock_usercnt (mutex, 1);
 269 }
 270 strong_alias (__pthread_mutex_unlock, pthread_mutex_unlock)
 271 strong_alias (__pthread_mutex_unlock, __pthread_mutex_unlock_internal)