1: /* Copyright (C) 2003, 2004, 2007 Free Software Foundation, Inc.
    2:    This file is part of the GNU C Library.
    3:    Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
    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 <endian.h>
   21: #include <errno.h>
   22: #include <sysdep.h>
   23: #include <lowlevellock.h>
   24: #include <pthread.h>
   25: #include <pthreadP.h>
   26: #include <kernel-features.h>
   27: 
   28: #include <shlib-compat.h>
   29: 
   30: 
   31: /* Cleanup handler, defined in pthread_cond_wait.c.  */
   32: extern void __condvar_cleanup (void *arg)
   33:      __attribute__ ((visibility ("hidden")));
   34: 
   35: struct _condvar_cleanup_buffer
   36: {
   37:   int oldtype;
   38:   pthread_cond_t *cond;
   39:   pthread_mutex_t *mutex;
   40:   unsigned int bc_seq;
   41: };
   42: 
   43: int
   44: __pthread_cond_timedwait (cond, mutex, abstime)
   45:      pthread_cond_t *cond;
   46:      pthread_mutex_t *mutex;
   47:      const struct timespec *abstime;
   48: {
   49:   struct _pthread_cleanup_buffer buffer;
   50:   struct _condvar_cleanup_buffer cbuffer;
   51:   int result = 0;
   52: 
   53:   /* Catch invalid parameters.  */
   54:   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
   55:     return EINVAL;
   56: 
   57:   int pshared = (cond->__data.__mutex == (void *) ~0l)
   58:                 ? LLL_SHARED : LLL_PRIVATE;
   59: 
   60:   /* Make sure we are along.  */
   61:   lll_lock (cond->__data.__lock, pshared);
   62: 
   63:   /* Now we can release the mutex.  */
   64:   int err = __pthread_mutex_unlock_usercnt (mutex, 0);
   65:   if (err)
   66:     {
   67:       lll_unlock (cond->__data.__lock, pshared);
   68:       return err;
   69:     }
   70: 
   71:   /* We have one new user of the condvar.  */
   72:   ++cond->__data.__total_seq;
   73:   ++cond->__data.__futex;
   74:   cond->__data.__nwaiters += 1 << COND_NWAITERS_SHIFT;
   75: 
   76:   /* Remember the mutex we are using here.  If there is already a
   77:      different address store this is a bad user bug.  Do not store
   78:      anything for pshared condvars.  */
   79:   if (cond->__data.__mutex != (void *) ~0l)
   80:     cond->__data.__mutex = mutex;
   81: 
   82:   /* Prepare structure passed to cancellation handler.  */
   83:   cbuffer.cond = cond;
   84:   cbuffer.mutex = mutex;
   85: 
   86:   /* Before we block we enable cancellation.  Therefore we have to
   87:      install a cancellation handler.  */
   88:   __pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer);
   89: 
   90:   /* The current values of the wakeup counter.  The "woken" counter
   91:      must exceed this value.  */
   92:   unsigned long long int val;
   93:   unsigned long long int seq;
   94:   val = seq = cond->__data.__wakeup_seq;
   95:   /* Remember the broadcast counter.  */
   96:   cbuffer.bc_seq = cond->__data.__broadcast_seq;
   97: 
   98:   while (1)
   99:     {
  100:       struct timespec rt;
  101:       {
  102: #ifdef __NR_clock_gettime
  103:         INTERNAL_SYSCALL_DECL (err);
  104:         int ret;
  105:         ret = INTERNAL_SYSCALL (clock_gettime, err, 2,
  106:                                 (cond->__data.__nwaiters
  107:                                  & ((1 << COND_NWAITERS_SHIFT) - 1)),
  108:                                 &rt);
  109: # ifndef __ASSUME_POSIX_TIMERS
  110:         if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (ret, err), 0))
  111:           {
  112:             struct timeval tv;
  113:             (void) gettimeofday (&tv, NULL);
  114: 
  115:             /* Convert the absolute timeout value to a relative timeout.  */
  116:             rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  117:             rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  118:           }
  119:         else
  120: # endif
  121:           {
  122:             /* Convert the absolute timeout value to a relative timeout.  */
  123:             rt.tv_sec = abstime->tv_sec - rt.tv_sec;
  124:             rt.tv_nsec = abstime->tv_nsec - rt.tv_nsec;
  125:           }
  126: #else
  127:         /* Get the current time.  So far we support only one clock.  */
  128:         struct timeval tv;
  129:         (void) gettimeofday (&tv, NULL);
  130: 
  131:         /* Convert the absolute timeout value to a relative timeout.  */
  132:         rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  133:         rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  134: #endif
  135:       }
  136:       if (rt.tv_nsec < 0)
  137:         {
  138:           rt.tv_nsec += 1000000000;
  139:           --rt.tv_sec;
  140:         }
  141:       /* Did we already time out?  */
  142:       if (__builtin_expect (rt.tv_sec < 0, 0))
  143:         {
  144:           if (cbuffer.bc_seq != cond->__data.__broadcast_seq)
  145:             goto bc_out;
  146: 
  147:           goto timeout;
  148:         }
  149: 
  150:       unsigned int futex_val = cond->__data.__futex;
  151: 
  152:       /* Prepare to wait.  Release the condvar futex.  */
  153:       lll_unlock (cond->__data.__lock, pshared);
  154: 
  155:       /* Enable asynchronous cancellation.  Required by the standard.  */
  156:       cbuffer.oldtype = __pthread_enable_asynccancel ();
  157: 
  158:       /* Wait until woken by signal or broadcast.  */
  159:       err = lll_futex_timed_wait (&cond->__data.__futex,
  160:                                   futex_val, &rt, pshared);
  161: 
  162:       /* Disable asynchronous cancellation.  */
  163:       __pthread_disable_asynccancel (cbuffer.oldtype);
  164: 
  165:       /* We are going to look at shared data again, so get the lock.  */
  166:       lll_lock (cond->__data.__lock, pshared);
  167: 
  168:       /* If a broadcast happened, we are done.  */
  169:       if (cbuffer.bc_seq != cond->__data.__broadcast_seq)
  170:         goto bc_out;
  171: 
  172:       /* Check whether we are eligible for wakeup.  */
  173:       val = cond->__data.__wakeup_seq;
  174:       if (val != seq && cond->__data.__woken_seq != val)
  175:         break;
  176: 
  177:       /* Not woken yet.  Maybe the time expired?  */
  178:       if (__builtin_expect (err == -ETIMEDOUT, 0))
  179:         {
  180:         timeout:
  181:           /* Yep.  Adjust the counters.  */
  182:           ++cond->__data.__wakeup_seq;
  183:           ++cond->__data.__futex;
  184: 
  185:           /* The error value.  */
  186:           result = ETIMEDOUT;
  187:           break;
  188:         }
  189:     }
  190: 
  191:   /* Another thread woken up.  */
  192:   ++cond->__data.__woken_seq;
  193: 
  194:  bc_out:
  195: 
  196:   cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT;
  197: 
  198:   /* If pthread_cond_destroy was called on this variable already,
  199:      notify the pthread_cond_destroy caller all waiters have left
  200:      and it can be successfully destroyed.  */
  201:   if (cond->__data.__total_seq == -1ULL
  202:       && cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT))
  203:     lll_futex_wake (&cond->__data.__nwaiters, 1, pshared);
  204: 
  205:   /* We are done with the condvar.  */
  206:   lll_unlock (cond->__data.__lock, pshared);
  207: 
  208:   /* The cancellation handling is back to normal, remove the handler.  */
  209:   __pthread_cleanup_pop (&buffer, 0);
  210: 
  211:   /* Get the mutex before returning.  */
  212:   err = __pthread_mutex_cond_lock (mutex);
  213: 
  214:   return err ?: result;
  215: }
  216: 
  217: versioned_symbol (libpthread, __pthread_cond_timedwait, pthread_cond_timedwait,
  218:                   GLIBC_2_3_2);