[PATCH i-g-t] lib/igt_kmod: Rewrite xe unload logic

[Lucas De Marchi]

Stop trying to unload possibly-dependent modules. Loading a module and
probing a module are 2 different things, although the Linux kernel will
by default probe devices when a module is loaded (for pci, configurable
in /sys/bus/pci/drivers_autoprobe).

For the unloading part we can simplify: instead of trying to unload
the modules directly (which may complain that module is already in use)
we just unplug the HW first.  For each possible device bound.

This will be come part of libkmod in future, but we don't need to wait:
we can implement it in igt too as it's straightforward.

For now this only switches the unload path for xe, but if it works well,
we can switch others in future too.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2362
Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
---

This works for me for the test above that was failing, but not thouroughly
tested with the rest of the tests that may trigger module load/unload.
Tested on BMG and DG2. YMMV :)

 lib/igt_kmod.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_kmod.h |  5 +----
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
index 464c0dcf4..1868fdbf7 100644
--- a/lib/igt_kmod.c
+++ b/lib/igt_kmod.c
@@ -697,6 +697,53 @@ igt_intel_driver_unload(const char *driver)
 	return 0;
 }
 
+static int unbind_xe(void)
+{
+	struct dirent *de;
+	DIR *dir;
+
+	dir = opendir("/sys/module/xe/drivers/pci:xe/");
+
+	/* Module may be loaded, but without any device bound */
+	if (!dir)
+		return 0;
+
+	while ((de = readdir(dir))) {
+		int devfd;
+		bool ret;
+
+		if (de->d_type != DT_LNK || !isdigit(de->d_name[0]))
+			continue;
+
+		devfd = openat(dirfd(dir), de->d_name, O_RDONLY | O_CLOEXEC);
+		igt_assert(devfd >= 0);
+
+		ret = igt_sysfs_set(devfd, "power/control", "auto");
+		igt_assert(ret);
+
+		ret = igt_sysfs_set(devfd, "driver/unbind", de->d_name);
+		igt_assert(ret);
+
+		close(devfd);
+		errno = 0;
+	}
+
+	igt_assert_eq(errno, 0);
+
+        return 0;
+}
+
+int igt_xe_driver_unload(void)
+{
+	unbind_xe();
+
+	igt_kmod_unload("xe");
+	if (igt_kmod_is_loaded("xe"))
+		return IGT_EXIT_FAILURE;
+
+	return IGT_EXIT_SUCCESS;
+}
+
 /**
  * igt_amdgpu_driver_load:
  * @opts: options to pass to amdgpu driver
diff --git a/lib/igt_kmod.h b/lib/igt_kmod.h
index efb46da12..ee1719a8f 100644
--- a/lib/igt_kmod.h
+++ b/lib/igt_kmod.h
@@ -63,10 +63,7 @@ static inline int igt_xe_driver_load(const char *opts)
 }
 
 
-static inline int igt_xe_driver_unload(void)
-{
-	return igt_intel_driver_unload("xe");
-}
+int igt_xe_driver_unload(void);
 
 int igt_amdgpu_driver_load(const char *opts);
 int igt_amdgpu_driver_unload(void);
-- 
2.43.0