nouveau: make nouveau importing global buffers completely thread-safe, with tests

While I've closed off most races in a previous patch, a small race still existed
where importing then unreffing cound cause an invalid bo. Add a test for this case.

Racing sequence fixed:

- thread 1 releases bo, refcount drops to zero, blocks on acquiring nvdev->lock.
- thread 2 increases refcount to 1.
- thread 2 decreases refcount to zero, blocks on acquiring nvdev->lock.

At this point the 2 threads will clean up the same bo.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@ubuntu.com>
Reviewed-By: Emil Velikov <emil.l.velikov@gmail.com>

3 files changed, 173 insertions, 0 deletions

diff --git a/tests/nouveau/.gitignore b/tests/nouveau/.gitignore
new file mode 100644
index 00000000..837bfb91
--- /dev/null
+++ b/tests/nouveau/.gitignore
@@ -0,0 +1 @@
+threaded
diff --git a/tests/nouveau/Makefile.am b/tests/nouveau/Makefile.am
new file mode 100644
index 00000000..c4f6e299
--- /dev/null
+++ b/tests/nouveau/Makefile.am
@@ -0,0 +1,16 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/include/drm \
+	-I$(top_srcdir)/nouveau \
+	-I$(top_srcdir)
+
+AM_CFLAGS = $(WARN_CFLAGS)
+
+LDADD = \
+	../../nouveau/libdrm_nouveau.la \
+	../../libdrm.la \
+	-ldl -lpthread
+
+TESTS = threaded
+
+check_PROGRAMS = $(TESTS)
+
diff --git a/tests/nouveau/threaded.c b/tests/nouveau/threaded.c
new file mode 100644
index 00000000..281af460
--- /dev/null
+++ b/tests/nouveau/threaded.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright © 2015 Canonical Ltd. (Maarten Lankhorst)
+ *
+ * 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 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include <sys/ioctl.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
+
+#include "xf86drm.h"
+#include "nouveau.h"
+
+static typeof(ioctl) *old_ioctl;
+static int failed;
+
+static int import_fd;
+
+int ioctl(int fd, unsigned long request, ...)
+{
+	va_list va;
+	int ret;
+	void *arg;
+
+	va_start(va, request);
+	arg = va_arg(va, void *);
+	ret = old_ioctl(fd, request, arg);
+	va_end(va);
+
+	if (ret < 0 && request == DRM_IOCTL_GEM_CLOSE && errno == EINVAL)
+		failed = 1;
+
+	return ret;
+}
+
+static void *
+openclose(void *dev)
+{
+	struct nouveau_device *nvdev = dev;
+	struct nouveau_bo *bo = NULL;
+	int i;
+
+	for (i = 0; i < 100000; ++i) {
+		if (!nouveau_bo_prime_handle_ref(nvdev, import_fd, &bo))
+			nouveau_bo_ref(NULL, &bo);
+	}
+	return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+	drmVersionPtr version;
+	const char *device = NULL;
+	int err, fd, fd2;
+	struct nouveau_device *nvdev, *nvdev2;
+	struct nouveau_bo *bo;
+	pthread_t t1, t2;
+
+	old_ioctl = dlsym(RTLD_NEXT, "ioctl");
+
+	if (argc < 2) {
+		fd = drmOpenWithType("nouveau", NULL, DRM_NODE_RENDER);
+		if (fd >= 0)
+			fd2 = drmOpenWithType("nouveau", NULL, DRM_NODE_RENDER);
+	} else {
+		device = argv[1];
+
+		fd = open(device, O_RDWR);
+		if (fd >= 0)
+			fd2 = open(device, O_RDWR);
+		else
+			fd2 = fd = -errno;
+	}
+
+	if (fd < 0) {
+		fprintf(stderr, "Opening nouveau render node failed with %i\n", fd);
+		return device ? -fd : 77;
+	}
+
+	if (fd2 < 0) {
+		fprintf(stderr, "Opening second nouveau render node failed with %i\n", -errno);
+		return errno;
+	}
+
+	version = drmGetVersion(fd);
+	if (version) {
+		printf("Version: %d.%d.%d\n", version->version_major,
+		       version->version_minor, version->version_patchlevel);
+		printf("  Name: %s\n", version->name);
+		printf("  Date: %s\n", version->date);
+		printf("  Description: %s\n", version->desc);
+
+		drmFreeVersion(version);
+	}
+
+	err = nouveau_device_wrap(fd, 0, &nvdev);
+	if (!err)
+		err = nouveau_device_wrap(fd2, 0, &nvdev2);
+	if (err < 0)
+		return 1;
+
+	err = nouveau_bo_new(nvdev2, NOUVEAU_BO_GART, 0, 4096, NULL, &bo);
+	if (!err)
+		err = nouveau_bo_set_prime(bo, &import_fd);
+
+	if (!err) {
+		pthread_create(&t1, NULL, openclose, nvdev);
+		pthread_create(&t2, NULL, openclose, nvdev);
+	}
+
+	pthread_join(t1, NULL);
+	pthread_join(t2, NULL);
+
+	close(import_fd);
+	nouveau_bo_ref(NULL, &bo);
+
+	nouveau_device_del(&nvdev2);
+	nouveau_device_del(&nvdev);
+	if (device) {
+		close(fd2);
+		close(fd);
+	} else {
+		drmClose(fd2);
+		drmClose(fd);
+	}
+
+	if (failed)
+		fprintf(stderr, "DRM_IOCTL_GEM_CLOSE failed with EINVAL,\n"
+				"race in opening/closing bo is likely.\n");
+
+	return failed;
+}