igt/vgem: Add a basic test for handling of module unload

We found a bug where a dmabuf did not keep the module alive (and so when
i915 tried to use it later, it exploded).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 80 insertions, 0 deletions

diff --git a/tests/vgem_basic.c b/tests/vgem_basic.c
index 591973d0..263ea5f0 100644
--- a/tests/vgem_basic.c
+++ b/tests/vgem_basic.c
@@ -188,6 +188,7 @@ static void test_dmabuf_fence(int fd)
 	igt_assert(!prime_busy(dmabuf, false));
 	igt_assert(!prime_busy(dmabuf, true));
 
+	close(dmabuf);
 	gem_close(fd, bo.handle);
 }
 
@@ -212,7 +213,9 @@ static void test_dmabuf_fence_before(int fd)
 	igt_assert(!prime_busy(dmabuf, false));
 	igt_assert(!prime_busy(dmabuf, true));
 
+	close(dmabuf);
 	gem_close(fd, bo.handle);
+
 	vgem_create(fd, &bo);
 
 	fence = vgem_fence_attach(fd, &bo, VGEM_FENCE_WRITE);
@@ -224,6 +227,7 @@ static void test_dmabuf_fence_before(int fd)
 	igt_assert(!prime_busy(dmabuf, false));
 	igt_assert(!prime_busy(dmabuf, true));
 
+	close(dmabuf);
 	gem_close(fd, bo.handle);
 }
 
@@ -284,6 +288,79 @@ static void test_debugfs_read(int fd)
 	close(dir);
 }
 
+static int module_unload(void)
+{
+	return system("/sbin/modprobe -s -r vgem");
+}
+
+static void test_unload(void)
+{
+	struct vgem_bo bo;
+	int vgem, dmabuf;
+	uint32_t *ptr;
+
+	igt_require(module_unload() == 0);
+
+	vgem = __drm_open_driver(DRIVER_VGEM);
+	igt_assert(vgem != -1);
+
+	/* The driver should stop the module from unloading */
+	igt_assert_f(module_unload() != 0,
+		     "open(//dev/vgem) should keep the module alive\n");
+
+	bo.width = 1024;
+	bo.height = 1;
+	bo.bpp = 32;
+	vgem_create(vgem, &bo);
+	close(vgem);
+
+	/* Closing the driver should clear all normal references */
+	igt_assert_f(module_unload() == 0,
+		     "No open(/dev/vgem), should be able to unload\n");
+
+	vgem = __drm_open_driver(DRIVER_VGEM);
+	igt_assert(vgem != -1);
+	bo.width = 1024;
+	bo.height = 1;
+	bo.bpp = 32;
+	vgem_create(vgem, &bo);
+	dmabuf = prime_handle_to_fd(vgem, bo.handle);
+	close(vgem);
+
+	/* A dmabuf should prevent module unload. */
+	igt_assert_f(module_unload() != 0,
+		     "A dmabuf should keep the module alive\n");
+
+	close(dmabuf);
+	igt_assert_f(module_unload() == 0,
+		     "No open dmabuf, should be able to unload\n");
+
+	vgem = __drm_open_driver(DRIVER_VGEM);
+	igt_assert(vgem != -1);
+	bo.width = 1024;
+	bo.height = 1;
+	bo.bpp = 32;
+	vgem_create(vgem, &bo);
+	dmabuf = prime_handle_to_fd_for_mmap(vgem, bo.handle);
+	close(vgem);
+
+	ptr = mmap(NULL, bo.size, PROT_WRITE, MAP_SHARED, dmabuf, 0);
+	igt_assert(ptr != MAP_FAILED);
+	close(dmabuf);
+
+	/* Although closed, the mmap should keep the dmabuf/module alive */
+	igt_assert_f(module_unload() != 0,
+		     "A mmap should keep the module alive\n");
+
+	for (int page = 0; page < bo.size >> 12; page++)
+		ptr[1024*page + page%1024] = page;
+
+	/* And finally we should have no more uses on the module. */
+	munmap(ptr, bo.size);
+	igt_assert_f(module_unload() == 0,
+		     "No open mmap, should be able to unload\n");
+}
+
 static bool has_prime_export(int fd)
 {
 	uint64_t value;
@@ -298,6 +375,9 @@ igt_main
 {
 	int fd = -1;
 
+	igt_subtest("unload")
+		test_unload();
+
 	igt_fixture {
 		fd = drm_open_driver(DRIVER_VGEM);
 	}