libpthread/nptl/pthread_mutex_unlock.c

   1 /* Copyright (C) 2002, 2003, 2005-2008, 2009 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include "pthreadP.h"
  23 #include <lowlevellock.h>
  24
  25 static int
  26 internal_function
  27 __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr)
  28      __attribute_noinline__;
  29
  30 int
  31 internal_function attribute_hidden
  32 __pthread_mutex_unlock_usercnt (
  33      pthread_mutex_t *mutex,
  34      int decr)
  35 {
  36   int type = PTHREAD_MUTEX_TYPE (mutex);
  37   if (__builtin_expect (type & ~PTHREAD_MUTEX_KIND_MASK_NP, 0))
  38     return __pthread_mutex_unlock_full (mutex, decr);
  39
  40   if (__builtin_expect (type, PTHREAD_MUTEX_TIMED_NP)
  41       == PTHREAD_MUTEX_TIMED_NP)
  42     {
  43       /* Always reset the owner field.  */
  44     normal:
  45       mutex->__data.__owner = 0;
  46       if (decr)
  47         /* One less user.  */
  48         --mutex->__data.__nusers;
  49
  50       /* Unlock.  */
  51       lll_unlock (mutex->__data.__lock, PTHREAD_MUTEX_PSHARED (mutex));
  52       return 0;
  53     }
  54   else if (__builtin_expect (type == PTHREAD_MUTEX_RECURSIVE_NP, 1))
  55     {
  56       /* Recursive mutex.  */
  57       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
  58         return EPERM;
  59
  60       if (--mutex->__data.__count != 0)
  61         /* We still hold the mutex.  */
  62         return 0;
  63       goto normal;
  64     }
  65   else if (__builtin_expect (type == PTHREAD_MUTEX_ADAPTIVE_NP, 1))
  66     goto normal;
  67   else
  68     {
  69       /* Error checking mutex.  */
  70       assert (type == PTHREAD_MUTEX_ERRORCHECK_NP);
  71       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)
  72           || ! lll_islocked (mutex->__data.__lock))
  73         return EPERM;
  74       goto normal;
  75     }
  76 }
  77
  78
  79 static int
  80 internal_function
  81 __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr)
  82 {
  83   int newowner = 0;
  84
  85   switch (PTHREAD_MUTEX_TYPE (mutex))
  86     {
  87     case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
  88       /* Recursive mutex.  */
  89       if ((mutex->__data.__lock & FUTEX_TID_MASK)
  90           == THREAD_GETMEM (THREAD_SELF, tid)
  91           && __builtin_expect (mutex->__data.__owner
  92                                == PTHREAD_MUTEX_INCONSISTENT, 0))
  93         {
  94           if (--mutex->__data.__count != 0)
  95             /* We still hold the mutex.  */
  96             return ENOTRECOVERABLE;
  97
  98           goto notrecoverable;
  99         }
 100
 101       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 102         return EPERM;
 103
 104       if (--mutex->__data.__count != 0)
 105         /* We still hold the mutex.  */
 106         return 0;
 107
 108       goto robust;
 109
 110     case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
 111     case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
 112     case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
 113       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 114           != THREAD_GETMEM (THREAD_SELF, tid)
 115           || ! lll_islocked (mutex->__data.__lock))
 116         return EPERM;
 117
 118       /* If the previous owner died and the caller did not succeed in
 119          making the state consistent, mark the mutex as unrecoverable
 120          and make all waiters.  */
 121       if (__builtin_expect (mutex->__data.__owner
 122                             == PTHREAD_MUTEX_INCONSISTENT, 0))
 123       notrecoverable:
 124         newowner = PTHREAD_MUTEX_NOTRECOVERABLE;
 125
 126     robust:
 127       /* Remove mutex from the list.  */
 128       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 129                      &mutex->__data.__list.__next);
 130       DEQUEUE_MUTEX (mutex);
 131
 132       mutex->__data.__owner = newowner;
 133       if (decr)
 134         /* One less user.  */
 135         --mutex->__data.__nusers;
 136
 137       /* Unlock.  */
 138       lll_robust_unlock (mutex->__data.__lock,
 139                          PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 140
 141       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 142       break;
 143
 144     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 145       /* Recursive mutex.  */
 146       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 147         return EPERM;
 148
 149       if (--mutex->__data.__count != 0)
 150         /* We still hold the mutex.  */
 151         return 0;
 152       goto continue_pi_non_robust;
 153
 154     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 155       /* Recursive mutex.  */
 156       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 157           == THREAD_GETMEM (THREAD_SELF, tid)
 158           && __builtin_expect (mutex->__data.__owner
 159                                == PTHREAD_MUTEX_INCONSISTENT, 0))
 160         {
 161           if (--mutex->__data.__count != 0)
 162             /* We still hold the mutex.  */
 163             return ENOTRECOVERABLE;
 164
 165           goto pi_notrecoverable;
 166         }
 167
 168       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 169         return EPERM;
 170
 171       if (--mutex->__data.__count != 0)
 172         /* We still hold the mutex.  */
 173         return 0;
 174
 175       goto continue_pi_robust;
 176
 177     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 178     case PTHREAD_MUTEX_PI_NORMAL_NP:
 179     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 180     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 181     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 182     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 183       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 184           != THREAD_GETMEM (THREAD_SELF, tid)
 185           || ! lll_islocked (mutex->__data.__lock))
 186         return EPERM;
 187
 188       /* If the previous owner died and the caller did not succeed in
 189          making the state consistent, mark the mutex as unrecoverable
 190          and make all waiters.  */
 191       if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0
 192           && __builtin_expect (mutex->__data.__owner
 193                                == PTHREAD_MUTEX_INCONSISTENT, 0))
 194       pi_notrecoverable:
 195        newowner = PTHREAD_MUTEX_NOTRECOVERABLE;
 196
 197       if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0)
 198         {
 199         continue_pi_robust:
 200           /* Remove mutex from the list.
 201              Note: robust PI futexes are signaled by setting bit 0.  */
 202           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 203                          (void *) (((uintptr_t) &mutex->__data.__list.__next)
 204                                    | 1));
 205           DEQUEUE_MUTEX (mutex);
 206         }
 207
 208     continue_pi_non_robust:
 209       mutex->__data.__owner = newowner;
 210       if (decr)
 211         /* One less user.  */
 212         --mutex->__data.__nusers;
 213
 214       /* Unlock.  */
 215       if ((mutex->__data.__lock & FUTEX_WAITERS) != 0
 216           || atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock, 0,
 217                                                    THREAD_GETMEM (THREAD_SELF,
 218                                                                   tid)))
 219         {
 220           int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 221           int private = (robust
 222                          ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
 223                          : PTHREAD_MUTEX_PSHARED (mutex));
 224           INTERNAL_SYSCALL_DECL (__err);
 225           INTERNAL_SYSCALL (futex, __err, 2, &mutex->__data.__lock,
 226                             __lll_private_flag (FUTEX_UNLOCK_PI, private));
 227         }
 228
 229       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 230       break;
 231
 232     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 233       /* Recursive mutex.  */
 234       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 235         return EPERM;
 236
 237       if (--mutex->__data.__count != 0)
 238         /* We still hold the mutex.  */
 239         return 0;
 240       goto pp;
 241
 242     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 243       /* Error checking mutex.  */
 244       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)
 245           || (mutex->__data.__lock & ~ PTHREAD_MUTEX_PRIO_CEILING_MASK) == 0)
 246         return EPERM;
 247       /* FALLTHROUGH */
 248
 249     case PTHREAD_MUTEX_PP_NORMAL_NP:
 250     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 251       /* Always reset the owner field.  */
 252     pp:
 253       mutex->__data.__owner = 0;
 254
 255       if (decr)
 256         /* One less user.  */
 257         --mutex->__data.__nusers;
 258
 259       /* Unlock.  */
 260       int newval, oldval;
 261       do
 262         {
 263           oldval = mutex->__data.__lock;
 264           newval = oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK;
 265         }
 266       while (atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock,
 267                                                    newval, oldval));
 268
 269       if ((oldval & ~PTHREAD_MUTEX_PRIO_CEILING_MASK) > 1)
 270         lll_futex_wake (&mutex->__data.__lock, 1,
 271                         PTHREAD_MUTEX_PSHARED (mutex));
 272
 273       int oldprio = newval >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 274       return __pthread_tpp_change_priority (oldprio, -1);
 275
 276     default:
 277       /* Correct code cannot set any other type.  */
 278       return EINVAL;
 279     }
 280
 281   return 0;
 282 }
 283
 284
 285 int
 286 attribute_protected
 287 __pthread_mutex_unlock (
 288      pthread_mutex_t *mutex)
 289 {
 290   return __pthread_mutex_unlock_usercnt (mutex, 1);
 291 }
 292 strong_alias (__pthread_mutex_unlock, pthread_mutex_unlock)
 293 strong_alias (__pthread_mutex_unlock, __pthread_mutex_unlock_internal)