sysdeps/pthread/tst-spin2.c

   1 /* Copyright (C) 2002-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <pthread.h>
  20 #include <stdint.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <sys/mman.h>
  26 #include <sys/wait.h>
  27
  28
  29 static int
  30 do_test (void)
  31 {
  32   size_t ps = sysconf (_SC_PAGESIZE);
  33   char tmpfname[] = "/tmp/tst-spin2.XXXXXX";
  34   char data[ps];
  35   void *mem;
  36   int fd;
  37   pthread_spinlock_t *s;
  38   pid_t pid;
  39   char *p;
  40   int err;
  41
  42   fd = mkstemp (tmpfname);
  43   if (fd == -1)
  44     {
  45       printf ("cannot open temporary file: %m\n");
  46       return 1;
  47     }
  48
  49   /* Make sure it is always removed.  */
  50   unlink (tmpfname);
  51
  52   /* Create one page of data.  */
  53   memset (data, '\0', ps);
  54
  55   /* Write the data to the file.  */
  56   if (write (fd, data, ps) != (ssize_t) ps)
  57     {
  58       puts ("short write");
  59       return 1;
  60     }
  61
  62   mem = mmap (NULL, ps, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  63   if (mem == MAP_FAILED)
  64     {
  65       printf ("mmap failed: %m\n");
  66       return 1;
  67     }
  68
  69   s = (pthread_spinlock_t *) (((uintptr_t) mem
  70                                + __alignof (pthread_spinlock_t))
  71                               & ~(__alignof (pthread_spinlock_t) - 1));
  72   p = (char *) (s + 1);
  73
  74   if (pthread_spin_init (s, PTHREAD_PROCESS_SHARED) != 0)
  75     {
  76       puts ("spin_init failed");
  77       return 1;
  78     }
  79
  80   if (pthread_spin_lock (s) != 0)
  81     {
  82       puts ("spin_lock failed");
  83       return 1;
  84     }
  85
  86   err = pthread_spin_trylock (s);
  87   if (err == 0)
  88     {
  89       puts ("1st spin_trylock succeeded");
  90       return 1;
  91     }
  92   else if (err != EBUSY)
  93     {
  94       puts ("1st spin_trylock didn't return EBUSY");
  95       return 1;
  96     }
  97
  98   err = pthread_spin_unlock (s);
  99   if (err != 0)
 100     {
 101       puts ("parent: spin_unlock failed");
 102       return 1;
 103     }
 104
 105   err = pthread_spin_trylock (s);
 106   if (err != 0)
 107     {
 108       puts ("2nd spin_trylock failed");
 109       return 1;
 110     }
 111
 112   *p = 0;
 113
 114   puts ("going to fork now");
 115   pid = fork ();
 116   if (pid == -1)
 117     {
 118       puts ("fork failed");
 119       return 1;
 120     }
 121   else if (pid == 0)
 122     {
 123       /* Play some lock ping-pong.  It's our turn to unlock first.  */
 124       if ((*p)++ != 0)
 125         {
 126           puts ("child: *p != 0");
 127           return 1;
 128         }
 129
 130       if (pthread_spin_unlock (s) != 0)
 131         {
 132           puts ("child: 1st spin_unlock failed");
 133           return 1;
 134         }
 135
 136       puts ("child done");
 137     }
 138   else
 139     {
 140       if (pthread_spin_lock (s) != 0)
 141         {
 142           puts ("parent: 2nd spin_lock failed");
 143           return 1;
 144         }
 145
 146       puts ("waiting for child");
 147
 148       waitpid (pid, NULL, 0);
 149
 150       puts ("parent done");
 151     }
 152
 153   return 0;
 154 }
 155
 156 #define TEST_FUNCTION do_test ()
 157 #include "../test-skeleton.c"