gdb/testsuite/gdb.trace/ftrace-lock.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2015-2023 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include <pthread.h>
  19 #include <unistd.h>
  20 #include "trace-common.h"
  21
  22 /* Called if the testcase failed.  */
  23 static void
  24 fail (void)
  25 {
  26 }
  27
  28 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  29
  30 /* This function overrides gdb_collect in the in-process agent library.
  31    See gdbserver/tracepoint.c (gdb_collect).  We want this function to
  32    be ran instead of the one from the library to easily check that only
  33    one thread is tracing at a time.
  34
  35    This works as expected because GDBserver will ask GDB about symbols
  36    present in the inferior with the 'qSymbol' packet.  And GDB will
  37    reply with the address of this function instead of the one from the
  38    in-process agent library.  */
  39
  40 void
  41 gdb_agent_gdb_collect (void *tpoint, unsigned char *regs)
  42 {
  43   /* If we cannot acquire a lock, then this means another thread is
  44      tracing and the lock implemented by the jump pad is not working!  */
  45   if (pthread_mutex_trylock (&mutex) != 0)
  46     {
  47       fail ();
  48       return;
  49     }
  50
  51   sleep (1);
  52
  53   if (pthread_mutex_unlock (&mutex) != 0)
  54     {
  55       fail ();
  56       return;
  57     }
  58 }
  59
  60 static void *
  61 thread_function (void *arg)
  62 {
  63   FAST_TRACEPOINT_LABEL(set_point);
  64 }
  65
  66 static void
  67 end (void)
  68 {
  69 }
  70
  71 int
  72 main (int argc, char *argv[], char *envp[])
  73 {
  74   pthread_t threads[NUM_THREADS];
  75   int i;
  76
  77   for (i = 0; i < NUM_THREADS; i++)
  78     pthread_create (&threads[i], NULL, thread_function, NULL);
  79
  80   for (i = 0; i < NUM_THREADS; i++)
  81     pthread_join (threads[i], NULL);
  82
  83   end ();
  84
  85   return 0;
  86 }