--- /dev/null
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2015 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <limits.h>
+
+/* How many threads fit in the target's thread number space. */
+long tid_max = -1;
+
+/* Number of threads spawned. */
+unsigned long thread_counter;
+
+/* How long it takes to spawn as many threads as fits in the thread
+ number space. On systems where thread IDs are just monotonically
+ incremented, this is enough for the tid numbers to wrap around. On
+ targets that randomize thread IDs, this is enough time to give each
+ number in the thread number space some chance of reuse. It'll be
+ capped to a lower value if we can't compute it. */
+unsigned int reuse_time = -1;
+
+void *
+do_nothing_thread_func (void *arg)
+{
+ usleep (1);
+ return NULL;
+}
+
+void *
+spawner_thread_func (void *arg)
+{
+ while (1)
+ {
+ pthread_t child;
+ int rc;
+
+ thread_counter++;
+
+ rc = pthread_create (&child, NULL, do_nothing_thread_func, NULL);
+ assert (rc == 0);
+
+ rc = pthread_join (child, NULL);
+ assert (rc == 0);
+ }
+
+ return NULL;
+}
+
+/* Called after the program is done counting number of spawned threads
+ for a period, to compute REUSE_TIME. */
+
+void
+after_count (void)
+{
+}
+
+/* Called after enough time has passed for TID reuse to occur. */
+
+void
+after_reuse_time (void)
+{
+}
+
+#ifdef __linux__
+
+/* Get the running system's configured pid_max. */
+
+static int
+linux_proc_get_pid_max (void)
+{
+ static const char filename[] ="/proc/sys/kernel/pid_max";
+ FILE *file;
+ char buf[100];
+ int retval = -1;
+
+ file = fopen (filename, "r");
+ if (file == NULL)
+ {
+ fprintf (stderr, "unable to open %s\n", filename);
+ return -1;
+ }
+
+ if (fgets (buf, sizeof (buf), file) != NULL)
+ retval = strtol (buf, NULL, 10);
+
+ fclose (file);
+ return retval;
+}
+
+#endif
+
+int
+main (int argc, char *argv[])
+{
+ pthread_t child;
+ int rc;
+ unsigned int reuse_time_raw = 0;
+
+ rc = pthread_create (&child, NULL, spawner_thread_func, NULL);
+ assert (rc == 0);
+
+#define COUNT_TIME 2
+ sleep (COUNT_TIME);
+
+#ifdef __linux__
+ tid_max = linux_proc_get_pid_max ();
+#endif
+ /* If we don't know how many threads it would take to use the whole
+ number space on this system, just run the test for a bit. */
+ if (tid_max > 0)
+ {
+ reuse_time_raw = tid_max / ((float) thread_counter / COUNT_TIME) + 0.5;
+
+ /* Give it a bit more, just in case. */
+ reuse_time = reuse_time_raw + 3;
+ }
+
+ /* 4 seconds were sufficient on the machine this was first observed,
+ an Intel i7-2620M @ 2.70GHz running Linux 3.18.7, with
+ pid_max=32768. Going forward, as machines get faster, this will
+ need less time, unless pid_max is set to a very high number. To
+ avoid unreasonably long test time, cap to an upper bound. */
+ if (reuse_time > 60)
+ reuse_time = 60;
+ printf ("thread_counter=%lu, tid_max = %ld, reuse_time_raw=%u, reuse_time=%u\n",
+ thread_counter, tid_max, reuse_time_raw, reuse_time);
+ after_count ();
+
+ sleep (reuse_time);
+
+ after_reuse_time ();
+ return 0;
+}
--- /dev/null
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Test running a program that spawns enough threads that the tid of an
+# exited thread is reused. GDB should not crash when this happens.
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile { debug pthreads }] == -1} {
+ return -1
+}
+
+clean_restart ${binfile}
+
+if ![runto main] {
+ fail "Can't run to main"
+ return -1
+}
+
+delete_breakpoints
+
+# Avoid dumping a ton of thread create/exit info in the logs.
+gdb_test_no_output "set print thread-events off"
+
+gdb_breakpoint "after_count"
+gdb_continue_to_breakpoint "after_count"
+
+# Get value of VARIABLE in the inferior.
+
+proc getvar {variable} {
+ global decimal
+ global gdb_prompt
+
+ set value 0
+
+ set msg "get $variable"
+ gdb_test_multiple "print $variable" $msg {
+ -re " = ($decimal)\r\n$gdb_prompt $" {
+ set value $expect_out(1,string)
+ pass $msg
+ }
+ }
+ return $value
+}
+
+set reuse_time [getvar "reuse_time"]
+
+# Now the real test. Run to a breakpoint in a thread that exits
+# immediately once resumed. The thread ends up left on the thread
+# list, marked exited (exactly because it's the selected thread).
+gdb_breakpoint "do_nothing_thread_func"
+gdb_continue_to_breakpoint "do_nothing_thread_func"
+
+delete_breakpoints
+
+# Let the program continue, constantly spawning short-lived threads
+# (one at a time). On some targets, after a bit, a new thread reuses
+# the tid of the old exited thread that we still have selected. GDB
+# should not crash in this situation. Of course, if the tid number
+# space is shared between all processes in the system (such as on
+# Linux), there's a chance that some other process grabs the TID, but
+# that can never cause a spurious test fail.
+gdb_breakpoint "after_reuse_time"
+
+# Higher than what the test program sleeps before exiting.
+set timeout [expr $reuse_time * 2]
+
+gdb_continue_to_breakpoint "after_reuse_time"
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