[PATCH 4.19 289/422] s390/zcrypt: enable AP bus scan without a valid default domain

[Greg Kroah-Hartman]

From: Halil Pasic <pasic@xxxxxxxxxxxxx>

[ Upstream commit 1c472d46283263497adccd7a0bec64ee2f9c09e5 ]

The AP bus scan is aborted before doing anything worth mentioning if
ap_select_domain() fails, e.g. if the ap_rights.aqm mask is all zeros.
As the result of this the ap bus fails to manage (e.g. create and
register) devices like it is supposed to.

Let us make ap_scan_bus() work even if ap_select_domain() can't select a
default domain. Let's also make ap_select_domain() return void, as there
are no more callers interested in its return value.

Signed-off-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Reported-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
Fixes: 7e0bdbe5c21c "s390/zcrypt: AP bus support for alternate driver(s)"
[freude@xxxxxxxxxxxxx: title and patch header slightly modified]
Signed-off-by: Harald Freudenberger <freude@xxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/s390/crypto/ap_bus.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 3be54651698a3..027a53eec42a5 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -1223,11 +1223,10 @@ static struct bus_attribute *const ap_bus_attrs[] = {
 };
 
 /**
- * ap_select_domain(): Select an AP domain.
- *
- * Pick one of the 16 AP domains.
+ * ap_select_domain(): Select an AP domain if possible and we haven't
+ * already done so before.
  */
-static int ap_select_domain(void)
+static void ap_select_domain(void)
 {
 	int count, max_count, best_domain;
 	struct ap_queue_status status;
@@ -1242,7 +1241,7 @@ static int ap_select_domain(void)
 	if (ap_domain_index >= 0) {
 		/* Domain has already been selected. */
 		spin_unlock_bh(&ap_domain_lock);
-		return 0;
+		return;
 	}
 	best_domain = -1;
 	max_count = 0;
@@ -1269,11 +1268,8 @@ static int ap_select_domain(void)
 	if (best_domain >= 0) {
 		ap_domain_index = best_domain;
 		AP_DBF(DBF_DEBUG, "new ap_domain_index=%d\n", ap_domain_index);
-		spin_unlock_bh(&ap_domain_lock);
-		return 0;
 	}
 	spin_unlock_bh(&ap_domain_lock);
-	return -ENODEV;
 }
 
 /*
@@ -1351,8 +1347,7 @@ static void ap_scan_bus(struct work_struct *unused)
 	AP_DBF(DBF_DEBUG, "%s running\n", __func__);
 
 	ap_query_configuration(ap_configuration);
-	if (ap_select_domain() != 0)
-		goto out;
+	ap_select_domain();
 
 	for (id = 0; id < AP_DEVICES; id++) {
 		/* check if device is registered */
@@ -1468,12 +1463,11 @@ static void ap_scan_bus(struct work_struct *unused)
 		}
 	} /* end device loop */
 
-	if (defdomdevs < 1)
+	if (ap_domain_index >= 0 && defdomdevs < 1)
 		AP_DBF(DBF_INFO,
 		       "no queue device with default domain %d available\n",
 		       ap_domain_index);
 
-out:
 	mod_timer(&ap_config_timer, jiffies + ap_config_time * HZ);
 }
 
-- 
2.20.1