Author: sewardj
Date: 2007-10-25 17:59:14 +0100 (Thu, 25 Oct 2007)
New Revision: 7033
Log:
Test semaphore handling, by using them to build a barrier.
Added:
branches/THRCHECK/thrcheck/tests/tc17_sembar.c
branches/THRCHECK/thrcheck/tests/tc17_sembar.stderr.exp
branches/THRCHECK/thrcheck/tests/tc17_sembar.stdout.exp
branches/THRCHECK/thrcheck/tests/tc17_sembar.vgtest
Modified:
branches/THRCHECK/thrcheck/tests/Makefile.am
Modified: branches/THRCHECK/thrcheck/tests/Makefile.am
===================================================================
--- branches/THRCHECK/thrcheck/tests/Makefile.am 2007-10-25 16:09:46 UTC
(rev 7032)
+++ branches/THRCHECK/thrcheck/tests/Makefile.am 2007-10-25 16:59:14 UTC
(rev 7033)
@@ -1,6 +1,4 @@
-# FIXME: this is completely bogus (a copy of Helgrind's one)
-
# For AM_FLAG_M3264_PRI
include $(top_srcdir)/Makefile.flags.am
@@ -42,7 +40,9 @@
tc15_laog_lockdel.vgtest tc15_laog_lockdel.stderr.exp \
tc15_laog_lockdel.stdout.exp \
tc16_byterace.vgtest tc16_byterace.stderr.exp \
- tc16_byterace.stdout.exp
+ tc16_byterace.stdout.exp \
+ tc17_sembar.vgtest tc17_sembar.stderr.exp \
+ tc17_sembar.stdout.exp
check_PROGRAMS = \
hg01_all_ok \
@@ -66,7 +66,8 @@
tc13_laog1 \
tc14_laog_dinphils \
tc15_laog_lockdel \
- tc16_byterace
+ tc16_byterace \
+ tc17_sembar
# is this necessary?
AM_CFLAGS = $(WERROR) -Winline -Wall -Wshadow -g $(AM_FLAG_M3264_PRI)
Added: branches/THRCHECK/thrcheck/tests/tc17_sembar.c
===================================================================
--- branches/THRCHECK/thrcheck/tests/tc17_sembar.c
(rev 0)
+++ branches/THRCHECK/thrcheck/tests/tc17_sembar.c 2007-10-25 16:59:14 UTC
(rev 7033)
@@ -0,0 +1,178 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <pthread.h>
+#include <semaphore.h>
+
+/* This is really a test of semaphore handling
+ (sem_{init,destroy,post,wait}). Using semaphores a barrier
+ function is created. Thrcheck does understand the barrier
+ semantics implied by the barrier, as pieced together from
+ happens-before relationships obtained from the component
+ semaphores. However, it does falsely report one race. Ah well. */
+
+/* This code is derived from
+ gcc-4.3-20071012/libgomp/config/posix/bar.c, which is
+
+ Copyright (C) 2005 Free Software Foundation, Inc.
+ Contributed by Richard Henderson <[EMAIL PROTECTED]>.
+
+ and available under version 2.1 or later of the GNU Lesser General
+ Public License.
+
+ Relative to the libgomp sources, the gomp_barrier_t type here has
+ an extra semaphore field, xxx. This is not functionally useful,
+ but it is used to create enough extra inter-thread dependencies
+ that the barrier-like behaviour of gomp_barrier_t is evident to
+ Thrcheck. There is no other purpose for the .xxx field. */
+
+typedef struct
+{
+ pthread_mutex_t mutex1;
+ pthread_mutex_t mutex2;
+ sem_t sem1;
+ sem_t sem2;
+ unsigned total;
+ unsigned arrived;
+ sem_t xxx;
+} gomp_barrier_t;
+
+typedef long bool;
+
+void
+gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
+{
+ pthread_mutex_init (&bar->mutex1, NULL);
+ pthread_mutex_init (&bar->mutex2, NULL);
+ sem_init (&bar->sem1, 0, 0);
+ sem_init (&bar->sem2, 0, 0);
+ sem_init (&bar->xxx, 0, 0);
+ bar->total = count;
+ bar->arrived = 0;
+}
+
+void
+gomp_barrier_destroy (gomp_barrier_t *bar)
+{
+ /* Before destroying, make sure all threads have left the barrier. */
+ pthread_mutex_lock (&bar->mutex1);
+ pthread_mutex_unlock (&bar->mutex1);
+
+ pthread_mutex_destroy (&bar->mutex1);
+ pthread_mutex_destroy (&bar->mutex2);
+ sem_destroy (&bar->sem1);
+ sem_destroy (&bar->sem2);
+ sem_destroy(&bar->xxx);
+}
+
+void
+gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)
+{
+ pthread_mutex_lock (&bar->mutex1);
+ bar->total = count;
+ pthread_mutex_unlock (&bar->mutex1);
+}
+
+void
+gomp_barrier_wait (gomp_barrier_t *bar)
+{
+ unsigned int n;
+ pthread_mutex_lock (&bar->mutex1);
+
+ ++bar->arrived;
+
+ if (bar->arrived == bar->total)
+ {
+ bar->arrived--;
+ n = bar->arrived;
+ if (n > 0)
+ {
+ { unsigned int i;
+ for (i = 0; i < n; i++)
+ sem_wait(&bar->xxx); // acquire an obvious dependency from
+ // all other threads arriving at the barrier
+ }
+ // 1 up n times, 2 down once
+ // now let all the other threads past the barrier, giving them
+ // an obvious dependency with this thread.
+ do
+ sem_post (&bar->sem1); // 1 up
+ while (--n != 0);
+ // and wait till the last thread has left
+ sem_wait (&bar->sem2); // 2 down
+ }
+ pthread_mutex_unlock (&bar->mutex1);
+ /* Resultat professionnel! First we made this thread have an
+ obvious (Thrcheck-visible) dependency on all other threads
+ calling gomp_barrier_wait. Then, we released them all again,
+ so they all have a (visible) dependency on this thread.
+ Transitively, the result is that all threads leaving the
+ barrier have a a Thrcheck-visible dependency on all threads
+ arriving at the barrier. As required. */
+ }
+ else
+ {
+ pthread_mutex_unlock (&bar->mutex1);
+ sem_post(&bar->xxx);
+ // first N-1 threads wind up waiting here
+ sem_wait (&bar->sem1); // 1 down
+
+ pthread_mutex_lock (&bar->mutex2);
+ n = --bar->arrived; /* XXX see below */
+ pthread_mutex_unlock (&bar->mutex2);
+
+ if (n == 0)
+ sem_post (&bar->sem2); // 2 up
+ }
+}
+
+
+/* re XXX, thrcheck reports a race at this point. It doesn't
+ understand that bar->arrived is protected by mutex1 whilst threads
+ are arriving at the barrier and by mutex2 whilst they are leaving,
+ but not consistently by either of them. Oh well. */
+
+gomp_barrier_t bar;
+
+void* child ( void* argV )
+{
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ gomp_barrier_wait( &bar );
+ return NULL;
+}
+
+#define NNN 4
+
+int main (int argc, char *argv[])
+{
+ int j;
+ long i; int res;
+ pthread_t thr[NNN];
+ fprintf(stderr, "starting\n");
+
+ for (j = 0; j < 1; j++) {
+ gomp_barrier_init( &bar, NNN );
+
+ for (i = 0; i < NNN; i++) {
+ res = pthread_create( &thr[i], NULL, child, (void*)i );
+ assert(!res);
+ }
+
+ for (i = 0; i < NNN; i++) {
+ res = pthread_join( thr[i], NULL );
+ assert(!res);
+ }
+
+ gomp_barrier_destroy( &bar );
+ }
+ fprintf(stderr, "done\n");
+
+ return 0;
+}
Added: branches/THRCHECK/thrcheck/tests/tc17_sembar.stderr.exp
===================================================================
--- branches/THRCHECK/thrcheck/tests/tc17_sembar.stderr.exp
(rev 0)
+++ branches/THRCHECK/thrcheck/tests/tc17_sembar.stderr.exp 2007-10-25
16:59:14 UTC (rev 7033)
@@ -0,0 +1,46 @@
+
+starting
+Thread #2 was created
+ at 0x........: clone (in /...libc...)
+ by 0x........: ...
+ by 0x........: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread...)
+ by 0x........: [EMAIL PROTECTED] (tc_intercepts.c:...)
+ by 0x........: main (tc17_sembar.c:164)
+
+Thread #3 was created
+ at 0x........: clone (in /...libc...)
+ by 0x........: ...
+ by 0x........: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread...)
+ by 0x........: [EMAIL PROTECTED] (tc_intercepts.c:...)
+ by 0x........: main (tc17_sembar.c:164)
+
+Thread #4 was created
+ at 0x........: clone (in /...libc...)
+ by 0x........: ...
+ by 0x........: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread...)
+ by 0x........: [EMAIL PROTECTED] (tc_intercepts.c:...)
+ by 0x........: main (tc17_sembar.c:164)
+
+Thread #5 was created
+ at 0x........: clone (in /...libc...)
+ by 0x........: ...
+ by 0x........: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread...)
+ by 0x........: [EMAIL PROTECTED] (tc_intercepts.c:...)
+ by 0x........: main (tc17_sembar.c:164)
+
+Possible data race during read of size 4 at 0x........
+ at 0x........: gomp_barrier_wait (tc17_sembar.c:122)
+ by 0x........: child (tc17_sembar.c:140)
+ by 0x........: mythread_wrapper (tc_intercepts.c:...)
+ by 0x........: ...
+ by 0x........: ...
+ Old state: shared-modified by threads #2, #3, #4, #5
+ New state: shared-modified by threads #2, #3, #4, #5
+ Reason: this thread, #2, holds no consistent locks
+ Last consistently used lock for 0x........ was first observed
+ at 0x........: pthread_mutex_init (tc_intercepts.c:...)
+ by 0x........: gomp_barrier_init (tc17_sembar.c:46)
+ by 0x........: main (tc17_sembar.c:161)
+done
+
+ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Added: branches/THRCHECK/thrcheck/tests/tc17_sembar.stdout.exp
===================================================================
Added: branches/THRCHECK/thrcheck/tests/tc17_sembar.vgtest
===================================================================
--- branches/THRCHECK/thrcheck/tests/tc17_sembar.vgtest
(rev 0)
+++ branches/THRCHECK/thrcheck/tests/tc17_sembar.vgtest 2007-10-25 16:59:14 UTC
(rev 7033)
@@ -0,0 +1 @@
+prog: tc17_sembar
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