[igt-dev] [PATCH i-g-t] i915/perf_pmu: Attempt to unload i915 while the PMU is active

[Chris Wilson]

If the PMU is active, it will be utilising the driver internals for its
sampling. Therefore we must not remove the driver while PMU is still
awake! Hence try to unload the module while the pmu is open.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/perf_pmu.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 94 insertions(+), 2 deletions(-)

diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index b9ca6a493..e08c5635a 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -28,6 +28,7 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <errno.h>
+#include <signal.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/times.h>
@@ -39,6 +40,8 @@
 
 #include "igt.h"
 #include "igt_core.h"
+#include "igt_device.h"
+#include "igt_kmod.h"
 #include "igt_perf.h"
 #include "igt_sysfs.h"
 #include "igt_pm.h"
@@ -930,6 +933,7 @@ event_wait(int gem_fd, const struct intel_execution_engine2 *e)
 	igt_require(has_secure_batches(fd));
 	igt_skip_on(IS_VALLEYVIEW(devid) || IS_CHERRYVIEW(devid));
 
+	igt_device_set_master(gem_fd);
 	kmstest_set_vt_graphics_mode();
 	igt_display_require(&data.display, gem_fd);
 
@@ -1860,6 +1864,85 @@ static void faulting_read(int gem_fd, const struct mmap_offset *t)
 	munmap(ptr, 4096);
 }
 
+static int unload_i915(void)
+{
+	bind_fbcon(false);
+
+	if (igt_kmod_is_loaded("snd_hda_intel")) {
+		igt_terminate_process(SIGTERM, "alsactl");
+		kick_snd_hda_intel();
+		if (igt_kmod_unload("snd_hda_intel", 0))
+			return -EAGAIN;
+	}
+
+	if (igt_kmod_is_loaded("snd_hdmi_lpe_audio")) {
+		igt_terminate_process(SIGTERM, "alsactl");
+		if (igt_kmod_unload("snd_hdmi_lpe_audio", 0))
+			return -EAGAIN;
+	}
+
+	if (igt_kmod_is_loaded("i915")) {
+		if (igt_kmod_unload("i915", 0))
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+static void test_unload(void)
+{
+	igt_fork(child, 1) {
+		const struct intel_execution_engine2 *e;
+		uint64_t *buf;
+		int count;
+		int i915;
+		int fd;
+
+		igt_debug("Unloading and then re-opening i915 device\n");
+		igt_require(unload_i915() == 0);
+		i915 = __drm_open_driver(DRIVER_INTEL);
+
+		igt_debug("Opening perf events\n");
+		fd = open_group(i915, I915_PMU_REQUESTED_FREQUENCY, -1);
+		open_group(fd, I915_PMU_ACTUAL_FREQUENCY, fd);
+		count = 2;
+
+		__for_each_physical_engine(i915, e) {
+			open_group(i915,
+					I915_PMU_ENGINE_BUSY(e->class, e->instance),
+					fd);
+			open_group(i915,
+					I915_PMU_ENGINE_SEMA(e->class, e->instance),
+					fd);
+			open_group(i915,
+					I915_PMU_ENGINE_WAIT(e->class, e->instance),
+					fd);
+			count += 3;
+		}
+
+		close(i915);
+
+		buf = calloc(count + 1, sizeof(uint64_t));
+		igt_assert(buf);
+
+		igt_debug("Read %d events from perf and trial unload\n", count);
+		pmu_read_multi(fd, count, buf);
+		igt_assert_eq(unload_i915(), -EBUSY);
+		pmu_read_multi(fd, count, buf);
+		sleep(2);
+
+		igt_debug("Close perf\n");
+		close(fd);
+
+		free(buf);
+	}
+	igt_waitchildren();
+
+	igt_debug("Final unload\n");
+	sleep(5);
+	igt_assert_eq(unload_i915(), 0);
+}
+
 #define test_each_engine(T, i915, e) \
 	igt_subtest_with_dynamic(T) __for_each_physical_engine(i915, e) \
 		igt_dynamic_f("%s", e->name)
@@ -1878,7 +1961,7 @@ igt_main
 	int fd = -1;
 
 	igt_fixture {
-		fd = drm_open_driver_master(DRIVER_INTEL);
+		fd = __drm_open_driver(DRIVER_INTEL);
 
 		igt_require_gem(fd);
 		igt_require(i915_perf_type_id(fd) > 0);
@@ -2101,7 +2184,7 @@ igt_main
 		int render_fd = -1;
 
 		igt_fixture {
-			render_fd = drm_open_driver_render(DRIVER_INTEL);
+			render_fd = __drm_open_driver_render(DRIVER_INTEL);
 			igt_require_gem(render_fd);
 
 			gem_quiescent_gpu(fd);
@@ -2116,4 +2199,13 @@ igt_main
 			close(render_fd);
 		}
 	}
+
+	igt_fixture {
+		close(fd);
+	}
+
+	igt_subtest("module-unload") {
+		for (int pass = 0; pass < 3; pass++)
+			test_unload();
+	}
 }
-- 
2.26.2