sysdeps/pthread/aio_notify.c

   1 /* Notify initiator of AIO request.
   2    Copyright (C) 1997-2001, 2003, 2004, 2006 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25 #include <aio_misc.h>
  26
  27 #ifndef aio_start_notify_thread
  28 # define aio_start_notify_thread() do { } while (0)
  29 #endif
  30
  31 struct notify_func
  32   {
  33     void (*func) (sigval_t);
  34     sigval_t value;
  35   };
  36
  37 static void *
  38 notify_func_wrapper (void *arg)
  39 {
  40   aio_start_notify_thread ();
  41   struct notify_func *const n = arg;
  42   void (*func) (sigval_t) = n->func;
  43   sigval_t value = n->value;
  44   free (n);
  45   (*func) (value);
  46   return NULL;
  47 }
  48
  49
  50 int
  51 internal_function
  52 #ifdef BROKEN_THREAD_SIGNALS
  53 __aio_notify_only (struct sigevent *sigev, pid_t caller_pid)
  54 #else
  55 __aio_notify_only (struct sigevent *sigev)
  56 #endif
  57 {
  58   int result = 0;
  59
  60   /* Send the signal to notify about finished processing of the request.  */
  61   if (__builtin_expect (sigev->sigev_notify == SIGEV_THREAD, 0))
  62     {
  63       /* We have to start a thread.  */
  64       pthread_t tid;
  65       pthread_attr_t attr, *pattr;
  66
  67       pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
  68       if (pattr == NULL)
  69         {
  70           pthread_attr_init (&attr);
  71           pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
  72           pattr = &attr;
  73         }
  74
  75       /* SIGEV may be freed as soon as we return, so we cannot let the
  76          notification thread use that pointer.  Even though a sigval_t is
  77          only one word and the same size as a void *, we cannot just pass
  78          the value through pthread_create as the argument and have the new
  79          thread run the user's function directly, because on some machines
  80          the calling convention for a union like sigval_t is different from
  81          that for a pointer type like void *.  */
  82       struct notify_func *nf = malloc (sizeof *nf);
  83       if (nf == NULL)
  84         result = -1;
  85       else
  86         {
  87           nf->func = sigev->sigev_notify_function;
  88           nf->value = sigev->sigev_value;
  89           if (pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
  90             {
  91               free (nf);
  92               result = -1;
  93             }
  94         }
  95     }
  96   else if (sigev->sigev_notify == SIGEV_SIGNAL)
  97     {
  98       /* We have to send a signal.  */
  99 #if _POSIX_REALTIME_SIGNALS
 100       /* Note that the standard gives us the option of using a plain
 101          non-queuing signal here when SA_SIGINFO is not set for the signal.  */
 102 # ifdef BROKEN_THREAD_SIGNALS
 103       if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, caller_pid)
 104           < 0)
 105         result = -1;
 106 # else
 107       if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, getpid ())
 108           < 0)
 109         result = -1;
 110 # endif
 111 #else
 112       /* There are no queued signals on this system at all.  */
 113       result = raise (sigev->sigev_signo);
 114 #endif
 115     }
 116
 117   return result;
 118 }
 119
 120
 121 void
 122 internal_function
 123 __aio_notify (struct requestlist *req)
 124 {
 125   struct waitlist *waitlist;
 126   struct aiocb *aiocbp = &req->aiocbp->aiocb;
 127
 128 #ifdef BROKEN_THREAD_SIGNALS
 129   if (__aio_notify_only (&aiocbp->aio_sigevent, req->caller_pid) != 0)
 130 #else
 131   if (__aio_notify_only (&aiocbp->aio_sigevent) != 0)
 132 #endif
 133     {
 134       /* XXX What shall we do if already an error is set by
 135          read/write/fsync?  */
 136       aiocbp->__error_code = errno;
 137       aiocbp->__return_value = -1;
 138     }
 139
 140   /* Now also notify possibly waiting threads.  */
 141   waitlist = req->waiting;
 142   while (waitlist != NULL)
 143     {
 144       struct waitlist *next = waitlist->next;
 145
 146       if (waitlist->sigevp == NULL)
 147         {
 148           if (waitlist->result != NULL && aiocbp->__return_value == -1)
 149             *waitlist->result = -1;
 150
 151 #ifdef DONT_NEED_AIO_MISC_COND
 152           AIO_MISC_NOTIFY (waitlist);
 153 #else
 154           /* Decrement the counter.  */
 155           --*waitlist->counterp;
 156
 157           pthread_cond_signal (waitlist->cond);
 158 #endif
 159         }
 160       else
 161         /* This is part of a asynchronous `lio_listio' operation.  If
 162            this request is the last one, send the signal.  */
 163         if (--*waitlist->counterp == 0)
 164           {
 165 #ifdef BROKEN_THREAD_SIGNALS
 166             __aio_notify_only (waitlist->sigevp, waitlist->caller_pid);
 167 #else
 168             __aio_notify_only (waitlist->sigevp);
 169 #endif
 170             /* This is tricky.  See lio_listio.c for the reason why
 171                this works.  */
 172             free ((void *) waitlist->counterp);
 173           }
 174
 175       waitlist = next;
 176     }
 177 }