[igt-dev] [PATCH i-g-t] lib/igt_kmod: Allow some leeway in igt_kmod_unload_r

[Jonathan Cavitt]

kmod_module_remove_module occasionally returns EAGAIN for mei_gsc
in the setup of some gem_lmem_swapping subtests.  Just because
EAGAIN is returned doesn't mean the module is lost and unable to
be unloaded.  Try again some number of times (currently 10) before
giving up.

Retries will occur for -EBUSY and -EAGAIN, as these imply the
system is waiting for the target module can simply be waited for.
All other errors exit immediately, but as the context for each
error informs their relative severity, no warnings will be issued.

References: VLK-30287, VLK-39629

Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
CC: Stuart Summers <stuart.summers at intel.com>
CC: Sandeep Kumar Parupalli <sandeep.kumar.parupalli at intel.com>
CC: Chris Wilson <chris.p.wilson at linux.intel.com>
Reviewed-by: Chris Wilson <chris.p.wilson at linux.intel.com>
---
 lib/igt_kmod.c | 41 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 38 insertions(+), 3 deletions(-)

diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
index 17090110c..c840f9a17 100644
--- a/lib/igt_kmod.c
+++ b/lib/igt_kmod.c
@@ -253,8 +253,11 @@ out:
 
 static int igt_kmod_unload_r(struct kmod_module *kmod, unsigned int flags)
 {
+#define MAX_TRIES	20
+#define SLEEP_DURATION	500000
 	struct kmod_list *holders, *pos;
-	int err = 0;
+	int err, tries;
+	const char *mod_name = kmod_module_get_name(kmod);
 
 	holders = kmod_module_get_holders(kmod);
 	kmod_list_foreach(pos, holders) {
@@ -269,7 +272,6 @@ static int igt_kmod_unload_r(struct kmod_module *kmod, unsigned int flags)
 		return err;
 
 	if (igt_kmod_is_loading(kmod)) {
-		const char *mod_name = kmod_module_get_name(kmod);
 		igt_debug("%s still initializing\n", mod_name);
 		err = igt_wait(!igt_kmod_is_loading(kmod), 10000, 100);
 		if (err < 0) {
@@ -279,7 +281,40 @@ static int igt_kmod_unload_r(struct kmod_module *kmod, unsigned int flags)
 		}
 	}
 
-	return kmod_module_remove_module(kmod, flags);
+	for (tries = 0; tries < MAX_TRIES; tries++) {
+		bool loop = false;
+
+		err = kmod_module_remove_module(kmod, flags);
+
+		/* Only loop in the following cases */
+		switch (err) {
+		case -EBUSY:
+		case -EAGAIN:
+			/* Waiting for module to be available */
+			loop = true;
+			break;
+		default:
+			break;
+                }
+		if (!loop)
+			break;
+
+		igt_debug("Module %s failed to unload with err: %d on attempt: %i\n",
+			  mod_name, err, tries + 1);
+
+		usleep(SLEEP_DURATION);
+	}
+
+	if (err == -ENOENT)
+		igt_debug("Module %s could not be found.  Skipping.\n", mod_name);
+	else if (err)
+		igt_info("Module %s failed to unload with err: %d after ~%.1fms\n",
+			 mod_name, err, SLEEP_DURATION*tries/1000.);
+	else if (tries)
+		igt_info("Module %s unload took ~%.1fms over %i attempts\n",
+			 mod_name, SLEEP_DURATION*tries/1000., tries + 1);
+
+	return err;
 }
 
 /**
-- 
2.25.1