nptl/tst-spin2.c

   1 /* Copyright (C) 2002 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <pthread.h>
  22 #include <stdint.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <sys/mman.h>
  28 #include <sys/wait.h>
  29
  30
  31 int
  32 main (void)
  33 {
  34   size_t ps = sysconf (_SC_PAGESIZE);
  35   char tmpfname[] = "/tmp/tst-spin2.XXXXXX";
  36   char data[ps];
  37   void *mem;
  38   int fd;
  39   pthread_spinlock_t *s;
  40   pid_t pid;
  41   char *p;
  42   int err;
  43
  44   fd = mkstemp (tmpfname);
  45   if (fd == -1)
  46     {
  47       printf ("cannot open temporary file: %m\n");
  48       exit (1);
  49     }
  50
  51   /* Make sure it is always removed.  */
  52   unlink (tmpfname);
  53
  54   /* Create one page of data.  */
  55   memset (data, '\0', ps);
  56
  57   /* Write the data to the file.  */
  58   if (write (fd, data, ps) != ps)
  59     {
  60       puts ("short write");
  61       exit (1);
  62     }
  63
  64   mem = mmap (NULL, ps, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  65   if (mem == MAP_FAILED)
  66     {
  67       printf ("mmap failed: %m\n");
  68       exit (1);
  69     }
  70
  71   s = (pthread_spinlock_t *) (((uintptr_t) mem
  72                                + __alignof (pthread_spinlock_t))
  73                               & ~(__alignof (pthread_spinlock_t) - 1));
  74   p = (char *) (s + 1);
  75
  76   if (pthread_spin_init (s, PTHREAD_PROCESS_SHARED) != 0)
  77     {
  78       puts ("spin_init failed");
  79       exit (1);
  80     }
  81
  82   if (pthread_spin_lock (s) != 0)
  83     {
  84       puts ("spin_lock failed");
  85       exit (1);
  86     }
  87
  88   err = pthread_spin_trylock (s);
  89   if (err == 0)
  90     {
  91       puts ("1st spin_trylock succeeded");
  92       exit (1);
  93     }
  94   else if (err != EBUSY)
  95     {
  96       puts ("1st spin_trylock didn't return EBUSY");
  97       exit (1);
  98     }
  99
 100   err = pthread_spin_unlock (s);
 101   if (err != 0)
 102     {
 103       puts ("parent: spin_unlock failed");
 104       exit (1);
 105     }
 106
 107   err = pthread_spin_trylock (s);
 108   if (err != 0)
 109     {
 110       puts ("2nd spin_trylock failed");
 111       exit (1);
 112     }
 113
 114   *p = 0;
 115
 116   puts ("going to fork now");
 117   pid = fork ();
 118   if (pid == -1)
 119     {
 120       puts ("fork failed");
 121       exit (1);
 122     }
 123   else if (pid == 0)
 124     {
 125       /* Play some lock ping-pong.  It's our turn to unlock first.  */
 126       if ((*p)++ != 0)
 127         {
 128           puts ("child: *p != 0");
 129           exit (1);
 130         }
 131
 132       if (pthread_spin_unlock (s) != 0)
 133         {
 134           puts ("child: 1st spin_unlock failed");
 135           exit (1);
 136         }
 137
 138       puts ("child done");
 139     }
 140   else
 141     {
 142       if (pthread_spin_lock (s) != 0)
 143         {
 144           puts ("parent: 2nd spin_lock failed");
 145           exit (1);
 146         }
 147
 148       puts ("waiting for child");
 149
 150       waitpid (pid, NULL, 0);
 151
 152       puts ("parent done");
 153     }
 154
 155   exit (0);
 156 }