Commit 3317785a authored by Harald Freudenberger's avatar Harald Freudenberger Committed by Heiko Carstens
Browse files

s390/ap: Fix wrong APQN fill calculation 



The upper limit of the firmware queue fill state for each APQN
is reported by the hwinfo.qd field. This field shows the
numbers 0-7 for 1-8 queue spaces available. But the exploiting
code assumed the real boundary is stored there and thus stoppes
queuing in messages one tick too early.

Correct the limit calculation and thus offer a boost
of 12.5% performance for high traffic on one APQN.

Fixes: d4c53ae8 ("s390/ap: store TAPQ hwinfo in struct ap_card")
Cc: stable@vger.kernel.org
Reported-by: default avatarIngo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: default avatarIngo Franzki <ifranzki@linux.ibm.com>
Signed-off-by: default avatarHarald Freudenberger <freude@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent d045e166

drivers/s390/crypto/ap_card.c

+1 −1
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ static ssize_t depth_show(struct device *dev, struct device_attribute *attr, 
{

	struct ap_card *ac = to_ap_card(dev);



	return sysfs_emit(buf, "%d\n", ac->hwinfo.qd);

	return sysfs_emit(buf, "%d\n", ac->hwinfo.qd + 1);

}



static DEVICE_ATTR_RO(depth);

drivers/s390/crypto/ap_queue.c

+1 −1
Original line number Diff line number Diff line
@@ -285,7 +285,7 @@ static enum ap_sm_wait ap_sm_write(struct ap_queue *aq) 
		list_move_tail(&ap_msg->list, &aq->pendingq);

		aq->requestq_count--;

		aq->pendingq_count++;

		if (aq->queue_count < aq->card->hwinfo.qd) {

		if (aq->queue_count < aq->card->hwinfo.qd + 1) {

			aq->sm_state = AP_SM_STATE_WORKING;

			return AP_SM_WAIT_AGAIN;

		}