nptl/pthread_mutex_unlock.c

   1 /* Copyright (C) 2002-2012 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 #include <stap-probe.h>
  25
  26 static int
  27 internal_function
  28 __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr)
  29      __attribute_noinline__;
  30
  31 int
  32 internal_function attribute_hidden
  33 __pthread_mutex_unlock_usercnt (mutex, decr)
  34      pthread_mutex_t *mutex;
  35      int decr;
  36 {
  37   int type = PTHREAD_MUTEX_TYPE (mutex);
  38   if (__builtin_expect (type & ~PTHREAD_MUTEX_KIND_MASK_NP, 0))
  39     return __pthread_mutex_unlock_full (mutex, decr);
  40
  41   if (__builtin_expect (type, PTHREAD_MUTEX_TIMED_NP)
  42       == PTHREAD_MUTEX_TIMED_NP)
  43     {
  44       /* Always reset the owner field.  */
  45     normal:
  46       mutex->__data.__owner = 0;
  47       if (decr)
  48         /* One less user.  */
  49         --mutex->__data.__nusers;
  50
  51       /* Unlock.  */
  52       lll_unlock (mutex->__data.__lock, PTHREAD_MUTEX_PSHARED (mutex));
  53
  54       LIBC_PROBE (mutex_release, 1, mutex);
  55
  56       return 0;
  57     }
  58   else if (__builtin_expect (type == PTHREAD_MUTEX_RECURSIVE_NP, 1))
  59     {
  60       /* Recursive mutex.  */
  61       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
  62         return EPERM;
  63
  64       if (--mutex->__data.__count != 0)
  65         /* We still hold the mutex.  */
  66         return 0;
  67       goto normal;
  68     }
  69   else if (__builtin_expect (type == PTHREAD_MUTEX_ADAPTIVE_NP, 1))
  70     goto normal;
  71   else
  72     {
  73       /* Error checking mutex.  */
  74       assert (type == PTHREAD_MUTEX_ERRORCHECK_NP);
  75       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)
  76           || ! lll_islocked (mutex->__data.__lock))
  77         return EPERM;
  78       goto normal;
  79     }
  80 }
  81
  82
  83 static int
  84 internal_function
  85 __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr)
  86 {
  87   int newowner = 0;
  88
  89   switch (PTHREAD_MUTEX_TYPE (mutex))
  90     {
  91     case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
  92       /* Recursive mutex.  */
  93       if ((mutex->__data.__lock & FUTEX_TID_MASK)
  94           == THREAD_GETMEM (THREAD_SELF, tid)
  95           && __builtin_expect (mutex->__data.__owner
  96                                == PTHREAD_MUTEX_INCONSISTENT, 0))
  97         {
  98           if (--mutex->__data.__count != 0)
  99             /* We still hold the mutex.  */
 100             return ENOTRECOVERABLE;
 101
 102           goto notrecoverable;
 103         }
 104
 105       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 106         return EPERM;
 107
 108       if (--mutex->__data.__count != 0)
 109         /* We still hold the mutex.  */
 110         return 0;
 111
 112       goto robust;
 113
 114     case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
 115     case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
 116     case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
 117       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 118           != THREAD_GETMEM (THREAD_SELF, tid)
 119           || ! lll_islocked (mutex->__data.__lock))
 120         return EPERM;
 121
 122       /* If the previous owner died and the caller did not succeed in
 123          making the state consistent, mark the mutex as unrecoverable
 124          and make all waiters.  */
 125       if (__builtin_expect (mutex->__data.__owner
 126                             == PTHREAD_MUTEX_INCONSISTENT, 0))
 127       notrecoverable:
 128         newowner = PTHREAD_MUTEX_NOTRECOVERABLE;
 129
 130     robust:
 131       /* Remove mutex from the list.  */
 132       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 133                      &mutex->__data.__list.__next);
 134       DEQUEUE_MUTEX (mutex);
 135
 136       mutex->__data.__owner = newowner;
 137       if (decr)
 138         /* One less user.  */
 139         --mutex->__data.__nusers;
 140
 141       /* Unlock.  */
 142       lll_robust_unlock (mutex->__data.__lock,
 143                          PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 144
 145       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 146       break;
 147
 148     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 149       /* Recursive mutex.  */
 150       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 151         return EPERM;
 152
 153       if (--mutex->__data.__count != 0)
 154         /* We still hold the mutex.  */
 155         return 0;
 156       goto continue_pi_non_robust;
 157
 158     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 159       /* Recursive mutex.  */
 160       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 161           == THREAD_GETMEM (THREAD_SELF, tid)
 162           && __builtin_expect (mutex->__data.__owner
 163                                == PTHREAD_MUTEX_INCONSISTENT, 0))
 164         {
 165           if (--mutex->__data.__count != 0)
 166             /* We still hold the mutex.  */
 167             return ENOTRECOVERABLE;
 168
 169           goto pi_notrecoverable;
 170         }
 171
 172       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 173         return EPERM;
 174
 175       if (--mutex->__data.__count != 0)
 176         /* We still hold the mutex.  */
 177         return 0;
 178
 179       goto continue_pi_robust;
 180
 181     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 182     case PTHREAD_MUTEX_PI_NORMAL_NP:
 183     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 184     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 185     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 186     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 187       if ((mutex->__data.__lock & FUTEX_TID_MASK)
 188           != THREAD_GETMEM (THREAD_SELF, tid)
 189           || ! lll_islocked (mutex->__data.__lock))
 190         return EPERM;
 191
 192       /* If the previous owner died and the caller did not succeed in
 193          making the state consistent, mark the mutex as unrecoverable
 194          and make all waiters.  */
 195       if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0
 196           && __builtin_expect (mutex->__data.__owner
 197                                == PTHREAD_MUTEX_INCONSISTENT, 0))
 198       pi_notrecoverable:
 199        newowner = PTHREAD_MUTEX_NOTRECOVERABLE;
 200
 201       if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0)
 202         {
 203         continue_pi_robust:
 204           /* Remove mutex from the list.
 205              Note: robust PI futexes are signaled by setting bit 0.  */
 206           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 207                          (void *) (((uintptr_t) &mutex->__data.__list.__next)
 208                                    | 1));
 209           DEQUEUE_MUTEX (mutex);
 210         }
 211
 212     continue_pi_non_robust:
 213       mutex->__data.__owner = newowner;
 214       if (decr)
 215         /* One less user.  */
 216         --mutex->__data.__nusers;
 217
 218       /* Unlock.  */
 219       if ((mutex->__data.__lock & FUTEX_WAITERS) != 0
 220           || atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock, 0,
 221                                                    THREAD_GETMEM (THREAD_SELF,
 222                                                                   tid)))
 223         {
 224           int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 225           int private = (robust
 226                          ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
 227                          : PTHREAD_MUTEX_PSHARED (mutex));
 228           INTERNAL_SYSCALL_DECL (__err);
 229           INTERNAL_SYSCALL (futex, __err, 2, &mutex->__data.__lock,
 230                             __lll_private_flag (FUTEX_UNLOCK_PI, private));
 231         }
 232
 233       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 234       break;
 235
 236     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 237       /* Recursive mutex.  */
 238       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid))
 239         return EPERM;
 240
 241       if (--mutex->__data.__count != 0)
 242         /* We still hold the mutex.  */
 243         return 0;
 244       goto pp;
 245
 246     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 247       /* Error checking mutex.  */
 248       if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)
 249           || (mutex->__data.__lock & ~ PTHREAD_MUTEX_PRIO_CEILING_MASK) == 0)
 250         return EPERM;
 251       /* FALLTHROUGH */
 252
 253     case PTHREAD_MUTEX_PP_NORMAL_NP:
 254     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 255       /* Always reset the owner field.  */
 256     pp:
 257       mutex->__data.__owner = 0;
 258
 259       if (decr)
 260         /* One less user.  */
 261         --mutex->__data.__nusers;
 262
 263       /* Unlock.  */
 264       int newval, oldval;
 265       do
 266         {
 267           oldval = mutex->__data.__lock;
 268           newval = oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK;
 269         }
 270       while (atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock,
 271                                                    newval, oldval));
 272
 273       if ((oldval & ~PTHREAD_MUTEX_PRIO_CEILING_MASK) > 1)
 274         lll_futex_wake (&mutex->__data.__lock, 1,
 275                         PTHREAD_MUTEX_PSHARED (mutex));
 276
 277       int oldprio = newval >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 278
 279       LIBC_PROBE (mutex_release, 1, mutex);
 280
 281       return __pthread_tpp_change_priority (oldprio, -1);
 282
 283     default:
 284       /* Correct code cannot set any other type.  */
 285       return EINVAL;
 286     }
 287
 288   LIBC_PROBE (mutex_release, 1, mutex);
 289   return 0;
 290 }
 291
 292
 293 int
 294 __pthread_mutex_unlock (mutex)
 295      pthread_mutex_t *mutex;
 296 {
 297   return __pthread_mutex_unlock_usercnt (mutex, 1);
 298 }
 299 strong_alias (__pthread_mutex_unlock, pthread_mutex_unlock)
 300 hidden_def (__pthread_mutex_unlock)