tests: add gem_flink_race

This exercises a race in the flink name descruction of the current drm
gem core. When racing a gem close with a gem open the open can sneak
in and cause the kernel to leak the flink name and its reference.

This results in leaked gem objects that won't get reaped even at drm
file close time. On my 2 core/4 threads snb machine this leaks on the
order of 1k objects per second.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/.gitignore

@@ -30,6 +30,7 @@ gem_exec_nop
 gem_fenced_exec_thrash
 gem_fence_thrash
 gem_flink
+gem_flink_race
 gem_gtt_concurrent_blit
 gem_gtt_cpu_tlb
 gem_gtt_speed

tests/Makefile.am

@@ -61,6 +61,7 @@ TESTS_progs = \
 	gem_exec_faulting_reloc \
 	gem_exec_lut_handle \
 	gem_fenced_exec_thrash \
+	gem_flink_race \
 	gem_gtt_cpu_tlb \
 	gem_gtt_speed \
 	gem_hangcheck_forcewake \
@@ -190,6 +191,7 @@ AM_CFLAGS += $(CAIRO_CFLAGS) $(LIBUDEV_CFLAGS) $(GLIB_CFLAGS)
 
 gem_fence_thrash_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
 gem_fence_thrash_LDADD = $(LDADD) -lpthread
+gem_flink_race_LDADD = $(LDADD) -lpthread
 gem_threaded_access_tiled_LDADD = $(LDADD) -lpthread
 
 gem_wait_render_timeout_LDADD = $(LDADD) -lrt

tests/gem_flink_race.c

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2013 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Daniel Vetter <daniel.vetter@ffwll.ch>
+ */
+
+#include <sys/ioctl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include "drmtest.h"
+#include "i915_drm.h"
+#include "intel_bufmgr.h"
+
+/* Testcase: check for flink/open vs. gem close races
+ *
+ * The gem flink open ioctl had a little race with gem close which could result
+ * in the flink name and corresponding reference getting leaked.
+ */
+
+/* We want lockless and I'm to lazy to dig out an atomic libarary. On x86 this
+ * works, too. */
+volatile int pls_die = 0;
+int fd;
+
+static void *thread_fn(void *p)
+{
+	struct drm_gem_open open_struct;
+	int ret;
+
+	while (!pls_die) {
+		memset(&open_struct, 0, sizeof(open_struct));
+
+		open_struct.name = 1;
+		ret = ioctl(fd, DRM_IOCTL_GEM_OPEN, &open_struct);
+		if (ret == 0)
+			gem_close(fd, open_struct.handle);
+	}
+
+	printf("meh\n");
+
+	return (void *)0;
+}
+
+int main(int argc, char **argv)
+{
+	int num_threads;
+	pthread_t *threads;
+	int r, i;
+	void *status;
+
+	drmtest_skip_on_simulation();
+
+	num_threads = sysconf(_SC_NPROCESSORS_ONLN) - 1;
+	if (!num_threads)
+		num_threads = 1;
+
+	threads = calloc(num_threads, sizeof(pthread_t));
+
+	fd = drm_open_any();
+	assert(fd >= 0);
+
+	for (i = 0; i < num_threads; i++) {
+		r = pthread_create(&threads[i], NULL, thread_fn, NULL);
+		assert(r == 0);
+	}
+
+	for (i = 0; i < 1000000; i++) {
+		uint32_t handle;
+
+		handle = gem_create(fd, 4096);
+
+		gem_flink(fd, handle);
+
+		gem_close(fd, handle);
+	}
+
+	pls_die = 1;
+
+	for (i = 0;  i < num_threads; i++) {
+		pthread_join(threads[i], &status);
+		assert(status == 0);
+	}
+
+	fd = drm_open_any();
+	assert(fd >= 0);
+
+	close(fd);
+
+	return 0;
+}