s390/ap: fix state machine hang after failure to enable irq

If for any reason the interrupt enable for an ap queue fails the
state machine run for the queue returned wrong return codes to the
caller. So the caller assumed interrupt support for this queue in
enabled and thus did not re-establish the high resolution timer used
for polling. In the end this let to a hang for the user space process
waiting "forever" for the reply.

This patch reworks these return codes to return correct indications
for the caller to re-establish the timer when a queue runs without
interrupt support.

Please note that this is fixing a wrong behavior after a first
failure (enable interrupt support for the queue) failed. However,
looks like this occasionally happens on KVM systems.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 11 insertions, 9 deletions

diff --git a/drivers/s390/crypto/ap_queue.c b/drivers/s390/crypto/ap_queue.c
index 669f96fddad6..d70c4d3d0907 100644
--- a/drivers/s390/crypto/ap_queue.c
+++ b/drivers/s390/crypto/ap_queue.c
@@ -19,7 +19,7 @@
 static void __ap_flush_queue(struct ap_queue *aq);
 
 /**
- * ap_queue_enable_interruption(): Enable interruption on an AP queue.
+ * ap_queue_enable_irq(): Enable interrupt support on this AP queue.
  * @qid: The AP queue number
  * @ind: the notification indicator byte
  *
@@ -27,7 +27,7 @@ static void __ap_flush_queue(struct ap_queue *aq);
  * value it waits a while and tests the AP queue if interrupts
  * have been switched on using ap_test_queue().
  */
-static int ap_queue_enable_interruption(struct ap_queue *aq, void *ind)
+static int ap_queue_enable_irq(struct ap_queue *aq, void *ind)
 {
 	struct ap_queue_status status;
 	struct ap_qirq_ctrl qirqctrl = { 0 };
@@ -218,7 +218,8 @@ static enum ap_sm_wait ap_sm_read(struct ap_queue *aq)
 		return AP_SM_WAIT_NONE;
 	case AP_RESPONSE_NO_PENDING_REPLY:
 		if (aq->queue_count > 0)
-			return AP_SM_WAIT_INTERRUPT;
+			return aq->interrupt ?
+				AP_SM_WAIT_INTERRUPT : AP_SM_WAIT_TIMEOUT;
 		aq->sm_state = AP_SM_STATE_IDLE;
 		return AP_SM_WAIT_NONE;
 	default:
@@ -272,7 +273,8 @@ static enum ap_sm_wait ap_sm_write(struct ap_queue *aq)
 		fallthrough;
 	case AP_RESPONSE_Q_FULL:
 		aq->sm_state = AP_SM_STATE_QUEUE_FULL;
-		return AP_SM_WAIT_INTERRUPT;
+		return aq->interrupt ?
+			AP_SM_WAIT_INTERRUPT : AP_SM_WAIT_TIMEOUT;
 	case AP_RESPONSE_RESET_IN_PROGRESS:
 		aq->sm_state = AP_SM_STATE_RESET_WAIT;
 		return AP_SM_WAIT_TIMEOUT;
@@ -322,7 +324,7 @@ static enum ap_sm_wait ap_sm_reset(struct ap_queue *aq)
 	case AP_RESPONSE_NORMAL:
 	case AP_RESPONSE_RESET_IN_PROGRESS:
 		aq->sm_state = AP_SM_STATE_RESET_WAIT;
-		aq->interrupt = AP_INTR_DISABLED;
+		aq->interrupt = false;
 		return AP_SM_WAIT_TIMEOUT;
 	default:
 		aq->dev_state = AP_DEV_STATE_ERROR;
@@ -355,7 +357,7 @@ static enum ap_sm_wait ap_sm_reset_wait(struct ap_queue *aq)
 	switch (status.response_code) {
 	case AP_RESPONSE_NORMAL:
 		lsi_ptr = ap_airq_ptr();
-		if (lsi_ptr && ap_queue_enable_interruption(aq, lsi_ptr) == 0)
+		if (lsi_ptr && ap_queue_enable_irq(aq, lsi_ptr) == 0)
 			aq->sm_state = AP_SM_STATE_SETIRQ_WAIT;
 		else
 			aq->sm_state = (aq->queue_count > 0) ?
@@ -396,7 +398,7 @@ static enum ap_sm_wait ap_sm_setirq_wait(struct ap_queue *aq)
 
 	if (status.irq_enabled == 1) {
 		/* Irqs are now enabled */
-		aq->interrupt = AP_INTR_ENABLED;
+		aq->interrupt = true;
 		aq->sm_state = (aq->queue_count > 0) ?
 			AP_SM_STATE_WORKING : AP_SM_STATE_IDLE;
 	}
@@ -586,7 +588,7 @@ static ssize_t interrupt_show(struct device *dev,
 	spin_lock_bh(&aq->lock);
 	if (aq->sm_state == AP_SM_STATE_SETIRQ_WAIT)
 		rc = scnprintf(buf, PAGE_SIZE, "Enable Interrupt pending.\n");
-	else if (aq->interrupt == AP_INTR_ENABLED)
+	else if (aq->interrupt)
 		rc = scnprintf(buf, PAGE_SIZE, "Interrupts enabled.\n");
 	else
 		rc = scnprintf(buf, PAGE_SIZE, "Interrupts disabled.\n");
@@ -767,7 +769,7 @@ struct ap_queue *ap_queue_create(ap_qid_t qid, int device_type)
 	aq->ap_dev.device.type = &ap_queue_type;
 	aq->ap_dev.device_type = device_type;
 	aq->qid = qid;
-	aq->interrupt = AP_INTR_DISABLED;
+	aq->interrupt = false;
 	spin_lock_init(&aq->lock);
 	INIT_LIST_HEAD(&aq->pendingq);
 	INIT_LIST_HEAD(&aq->requestq);