sysdeps/pthread/aio_notify.c

   1 /* Notify initiator of AIO request.
   2    Copyright (C) 1997-2014 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <pthread.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <aio_misc.h>
  25
  26 #ifndef aio_start_notify_thread
  27 # define aio_start_notify_thread() do { } while (0)
  28 #endif
  29
  30 struct notify_func
  31   {
  32     void (*func) (sigval_t);
  33     sigval_t value;
  34   };
  35
  36 static void *
  37 notify_func_wrapper (void *arg)
  38 {
  39   aio_start_notify_thread ();
  40   struct notify_func *const n = arg;
  41   void (*func) (sigval_t) = n->func;
  42   sigval_t value = n->value;
  43   free (n);
  44   (*func) (value);
  45   return NULL;
  46 }
  47
  48
  49 int
  50 internal_function
  51 #ifdef BROKEN_THREAD_SIGNALS
  52 __aio_notify_only (struct sigevent *sigev, pid_t caller_pid)
  53 #else
  54 __aio_notify_only (struct sigevent *sigev)
  55 #endif
  56 {
  57   int result = 0;
  58
  59   /* Send the signal to notify about finished processing of the request.  */
  60   if (__builtin_expect (sigev->sigev_notify == SIGEV_THREAD, 0))
  61     {
  62       /* We have to start a thread.  */
  63       pthread_t tid;
  64       pthread_attr_t attr, *pattr;
  65
  66       pattr = (pthread_attr_t *) sigev->sigev_notify_attributes;
  67       if (pattr == NULL)
  68         {
  69           pthread_attr_init (&attr);
  70           pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
  71           pattr = &attr;
  72         }
  73
  74       /* SIGEV may be freed as soon as we return, so we cannot let the
  75          notification thread use that pointer.  Even though a sigval_t is
  76          only one word and the same size as a void *, we cannot just pass
  77          the value through pthread_create as the argument and have the new
  78          thread run the user's function directly, because on some machines
  79          the calling convention for a union like sigval_t is different from
  80          that for a pointer type like void *.  */
  81       struct notify_func *nf = malloc (sizeof *nf);
  82       if (nf == NULL)
  83         result = -1;
  84       else
  85         {
  86           nf->func = sigev->sigev_notify_function;
  87           nf->value = sigev->sigev_value;
  88           if (pthread_create (&tid, pattr, notify_func_wrapper, nf) < 0)
  89             {
  90               free (nf);
  91               result = -1;
  92             }
  93         }
  94     }
  95   else if (sigev->sigev_notify == SIGEV_SIGNAL)
  96     {
  97       /* We have to send a signal.  */
  98 #if _POSIX_REALTIME_SIGNALS > 0
  99       /* Note that the standard gives us the option of using a plain
 100          non-queuing signal here when SA_SIGINFO is not set for the signal.  */
 101 # ifdef BROKEN_THREAD_SIGNALS
 102       if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, caller_pid)
 103           < 0)
 104         result = -1;
 105 # else
 106       if (__aio_sigqueue (sigev->sigev_signo, sigev->sigev_value, getpid ())
 107           < 0)
 108         result = -1;
 109 # endif
 110 #else
 111       /* There are no queued signals on this system at all.  */
 112       result = raise (sigev->sigev_signo);
 113 #endif
 114     }
 115
 116   return result;
 117 }
 118
 119
 120 void
 121 internal_function
 122 __aio_notify (struct requestlist *req)
 123 {
 124   struct waitlist *waitlist;
 125   struct aiocb *aiocbp = &req->aiocbp->aiocb;
 126
 127 #ifdef BROKEN_THREAD_SIGNALS
 128   if (__aio_notify_only (&aiocbp->aio_sigevent, req->caller_pid) != 0)
 129 #else
 130   if (__aio_notify_only (&aiocbp->aio_sigevent) != 0)
 131 #endif
 132     {
 133       /* XXX What shall we do if already an error is set by
 134          read/write/fsync?  */
 135       aiocbp->__error_code = errno;
 136       aiocbp->__return_value = -1;
 137     }
 138
 139   /* Now also notify possibly waiting threads.  */
 140   waitlist = req->waiting;
 141   while (waitlist != NULL)
 142     {
 143       struct waitlist *next = waitlist->next;
 144
 145       if (waitlist->sigevp == NULL)
 146         {
 147           if (waitlist->result != NULL && aiocbp->__return_value == -1)
 148             *waitlist->result = -1;
 149
 150 #ifdef DONT_NEED_AIO_MISC_COND
 151           AIO_MISC_NOTIFY (waitlist);
 152 #else
 153           /* Decrement the counter.  */
 154           --*waitlist->counterp;
 155
 156           pthread_cond_signal (waitlist->cond);
 157 #endif
 158         }
 159       else
 160         /* This is part of an asynchronous `lio_listio' operation.  If
 161            this request is the last one, send the signal.  */
 162         if (--*waitlist->counterp == 0)
 163           {
 164 #ifdef BROKEN_THREAD_SIGNALS
 165             __aio_notify_only (waitlist->sigevp, waitlist->caller_pid);
 166 #else
 167             __aio_notify_only (waitlist->sigevp);
 168 #endif
 169             /* This is tricky.  See lio_listio.c for the reason why
 170                this works.  */
 171             free ((void *) waitlist->counterp);
 172           }
 173
 174       waitlist = next;
 175     }
 176 }