Re: [PATCH 8/8] add non-stop test that stresses thread starvation issues

[Yao Qi <qiyaoltc at gmail dot com>]

Pedro Alves <palves@redhat.com> writes:

> Yes, the test runs forever otherwise.  See:
>
>   https://sourceware.org/gdb/wiki/GDBTestcaseCookbook#Don.27t_write_tests_that_run_forever
>
> How about fixing this like attach-many-short-lived-threads.exp was
> fixed here:
>
>   https://sourceware.org/ml/gdb-patches/2015-02/msg00152.html
>
> ?
>

OK, how about the patch below?

>> It causes some fails on
>> arm-linux, that is, the board is slow, and alarm is triggered.
>> Then thread is disappeared and current_thread is set to NULL.
>> GDB/GDBserver doesn't know about that.  When the inferior memory is
>> accessed, current_thread is dereferenced, and GDBserver is crashed.
>
> Sounds like we should have a test that explicitly covers that.
> GDBserver shouldn't crash.

Yes, let me think about a test case to cover that.

-- 
Yao (éå)

From: Yao Qi <yao.qi@linaro.org>
Subject: [PATCH] Properly set alarm value in gdb.threads/non-stop-fair-events.exp

Nowadays, the alarm value is 60, and alarm is generated on some slow
boards.  This patch is to pass DejaGNU timeout value to the program,
and move the alarm call before going to infinite loop.  If any thread
has activities, the alarm is reset.

gdb/testsuite:

2015-04-07  Yao Qi  <yao.qi@linaro.org>

	* gdb.threads/non-stop-fair-events.c (SECONDS): New macro.
	(child_function): Call alarm.
	(main): Move call to alarm into the loop.
	* gdb.threads/non-stop-fair-events.exp: Build program with
	-DTIMEOUT=$timeout.

diff --git a/gdb/testsuite/gdb.threads/non-stop-fair-events.c b/gdb/testsuite/gdb.threads/non-stop-fair-events.c
index 6a9d31d..f82c366 100644
--- a/gdb/testsuite/gdb.threads/non-stop-fair-events.c
+++ b/gdb/testsuite/gdb.threads/non-stop-fair-events.c
@@ -22,6 +22,9 @@
 
 #define NUM_THREADS 10
 const int num_threads = NUM_THREADS;
+/* Allow for as much timeout as DejaGnu wants, plus a bit of
+   slack.  */
+#define SECONDS (TIMEOUT + 20)
 
 pthread_t child_thread[NUM_THREADS];
 volatile pthread_t signal_thread;
@@ -53,6 +56,8 @@ child_function (void *arg)
 
   while (1)
     {
+      /* Reset the timer before going to INF_LOOP.  */
+      alarm (SECONDS);
       INF_LOOP; /* set thread breakpoint here */
       loop_broke ();
     }
@@ -64,8 +69,6 @@ main (void)
   int res;
   int i;
 
-  alarm (60);
-
   signal (SIGUSR1, handler);
 
   for (i = 0; i < NUM_THREADS; i++)
@@ -76,6 +79,8 @@ main (void)
   while (1)
     {
       pthread_kill (signal_thread, SIGUSR1); /* set kill breakpoint here */
+      /* Reset the timer before going to INF_LOOP.  */
+      alarm (SECONDS);
       INF_LOOP;
       loop_broke ();
     }
diff --git a/gdb/testsuite/gdb.threads/non-stop-fair-events.exp b/gdb/testsuite/gdb.threads/non-stop-fair-events.exp
index 9b7b9ca..e2d3f7d 100644
--- a/gdb/testsuite/gdb.threads/non-stop-fair-events.exp
+++ b/gdb/testsuite/gdb.threads/non-stop-fair-events.exp
@@ -24,7 +24,8 @@ if [target_info exists gdb,nosignals] {
     return -1
 }
 
-if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug pthreads}] == -1} {
+set options { "additional_flags=-DTIMEOUT=$timeout" debug pthreads }
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile $options] == -1} {
     return -1
 }