[igt-dev] [PATCH i-g-t 2/2] i915/i915_module_load: Raise a fatal-error on failing to unload a module

[Zbigniew Kempczyński]

From: Chris Wilson <chris.p.wilson at linux.intel.com>

If we fail to unload the module after the fault-injection test, we leave
behind a dangerous modparam that will affect all subsequent tests.
Better to declare the run void rather than have to triage all the bizarre
bugs.

Somes the fault injection module load test timeouts out, causing
igt_runner to cancel the test with a SIGQUIT. This unfortunately causes
us to abort in the middle of the test leaving the module in a broken
state. That broken module is then used for subsequent tests, casuing a
cascade of failures.

Signed-off-by: Chris Wilson <chris.p.wilson at linux.intel.com>
Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Cc: Petri Latvala <petri.latvala at intel.com>
Cc: Jonathan Cavitt <jonathan.cavitt at intel.com>
---
 tests/i915/i915_module_load.c | 37 ++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/tests/i915/i915_module_load.c b/tests/i915/i915_module_load.c
index a922af0064..170900b1ab 100644
--- a/tests/i915/i915_module_load.c
+++ b/tests/i915/i915_module_load.c
@@ -163,6 +163,33 @@ static int open_parameters(const char *module_name)
 	return open(path, O_RDONLY);
 }
 
+static void unload_or_die(const char *module_name)
+{
+	int err, loop;
+
+	/* should be unloaded, so expect a no-op */
+	for (loop = 0;; loop++) {
+		err = igt_kmod_unload(module_name, 0);
+		if (err && err == -ENOENT) /* -ENOENT == unloaded already */
+			err = 0;
+		if (!err || loop >= 10)
+			break;
+
+		sleep(1); /* wait for external clients to drop */
+		if (!strcmp(module_name, "i915"))
+			igt_i915_driver_unload();
+	}
+
+	igt_abort_on_f(err,
+		       "Failed to unload '%s' err:%d after %ds, leaving dangerous modparams intact!\n",
+		       module_name, err, loop);
+}
+
+static void must_unload(int sig)
+{
+	unload_or_die("i915");
+}
+
 static int
 inject_fault(const char *module_name, const char *opt, int fault)
 {
@@ -306,6 +333,14 @@ igt_main
 
 		igt_i915_driver_unload();
 
+		/*
+		 * inject_fault() leaves the module unloaded, but if that fails
+		 * we must abort the run. Otherwise, we leave a dangerous
+		 * modparam affecting all subsequent tests causing bizarre
+		 * failures.
+		 */
+		igt_install_exit_handler(must_unload);
+
 		i = 0;
 		param = getenv("IGT_SRANDOM");
 		if (param)
@@ -324,7 +359,7 @@ igt_main
 		while (inject_fault("i915", param, i += 1 + random() % 17) == 0)
 			;
 
-		/* inject_fault() leaves the module unloaded */
+		unload_or_die("i915");
 	}
 
 	/* Subtests should unload the module themselves if they use modparams */
-- 
2.34.1