s390/qeth: fix dangling IO buffers after halt/clear

The cio layer's intparm logic does not align itself well with how qeth
manages cmd IOs. When an active IO gets terminated via halt/clear, the
corresponding IRQ's intparm does not reflect the cmd buffer but rather
the intparm that was passed to ccw_device_halt() / ccw_device_clear().
This behaviour was recently clarified in
commit b91d9e67e50b ("s390/cio: fix intparm documentation").

As a result, qeth_irq() currently doesn't cancel a cmd that was
terminated via halt/clear. This primarily causes us to leak
card->read_cmd after the qeth device is removed, since our IO path still
holds a refcount for this cmd.

For qeth this means that we need to keep track of which IO is pending on
a device ('active_cmd'), and use this as the intparm when calling
halt/clear. Otherwise qeth_irq() can't match the subsequent IRQ to its
cmd buffer.
Since we now keep track of the _expected_ intparm, we can also detect
any mismatch; this would constitute a bug somewhere in the lower layers.
In this case cancel the active cmd - we effectively "lost" the IRQ and
should not expect any further notification for this IO.

Fixes: 405548959cc7 ("s390/qeth: add support for dynamically allocated cmds")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 51 insertions, 20 deletions

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 634913112441..b9a2349e4b90 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -515,7 +515,9 @@ static int __qeth_issue_next_read(struct qeth_card *card)
 
 	QETH_CARD_TEXT(card, 6, "noirqpnd");
 	rc = ccw_device_start(channel->ccwdev, ccw, (addr_t) iob, 0, 0);
-	if (rc) {
+	if (!rc) {
+		channel->active_cmd = iob;
+	} else {
 		QETH_DBF_MESSAGE(2, "error %i on device %x when starting next read ccw!\n",
 				 rc, CARD_DEVID(card));
 		atomic_set(&channel->irq_pending, 0);
@@ -986,8 +988,21 @@ static void qeth_irq(struct ccw_device *cdev, unsigned long intparm,
 		QETH_CARD_TEXT(card, 5, "data");
 	}
 
-	if (qeth_intparm_is_iob(intparm))
-		iob = (struct qeth_cmd_buffer *) __va((addr_t)intparm);
+	if (intparm == 0) {
+		QETH_CARD_TEXT(card, 5, "irqunsol");
+	} else if ((addr_t)intparm != (addr_t)channel->active_cmd) {
+		QETH_CARD_TEXT(card, 5, "irqunexp");
+
+		dev_err(&cdev->dev,
+			"Received IRQ with intparm %lx, expected %px\n",
+			intparm, channel->active_cmd);
+		if (channel->active_cmd)
+			qeth_cancel_cmd(channel->active_cmd, -EIO);
+	} else {
+		iob = (struct qeth_cmd_buffer *) (addr_t)intparm;
+	}
+
+	channel->active_cmd = NULL;
 
 	rc = qeth_check_irb_error(card, cdev, irb);
 	if (rc) {
@@ -1007,15 +1022,10 @@ static void qeth_irq(struct ccw_device *cdev, unsigned long intparm,
 	if (irb->scsw.cmd.fctl & (SCSW_FCTL_HALT_FUNC))
 		channel->state = CH_STATE_HALTED;
 
-	if (intparm == QETH_CLEAR_CHANNEL_PARM) {
-		QETH_CARD_TEXT(card, 6, "clrchpar");
-		/* we don't have to handle this further */
-		intparm = 0;
-	}
-	if (intparm == QETH_HALT_CHANNEL_PARM) {
-		QETH_CARD_TEXT(card, 6, "hltchpar");
-		/* we don't have to handle this further */
-		intparm = 0;
+	if (iob && (irb->scsw.cmd.fctl & (SCSW_FCTL_CLEAR_FUNC |
+					  SCSW_FCTL_HALT_FUNC))) {
+		qeth_cancel_cmd(iob, -ECANCELED);
+		iob = NULL;
 	}
 
 	cstat = irb->scsw.cmd.cstat;
@@ -1408,7 +1418,7 @@ static int qeth_clear_channel(struct qeth_card *card,
 
 	QETH_CARD_TEXT(card, 3, "clearch");
 	spin_lock_irq(get_ccwdev_lock(channel->ccwdev));
-	rc = ccw_device_clear(channel->ccwdev, QETH_CLEAR_CHANNEL_PARM);
+	rc = ccw_device_clear(channel->ccwdev, (addr_t)channel->active_cmd);
 	spin_unlock_irq(get_ccwdev_lock(channel->ccwdev));
 
 	if (rc)
@@ -1430,7 +1440,7 @@ static int qeth_halt_channel(struct qeth_card *card,
 
 	QETH_CARD_TEXT(card, 3, "haltch");
 	spin_lock_irq(get_ccwdev_lock(channel->ccwdev));
-	rc = ccw_device_halt(channel->ccwdev, QETH_HALT_CHANNEL_PARM);
+	rc = ccw_device_halt(channel->ccwdev, (addr_t)channel->active_cmd);
 	spin_unlock_irq(get_ccwdev_lock(channel->ccwdev));
 
 	if (rc)
@@ -1444,6 +1454,25 @@ static int qeth_halt_channel(struct qeth_card *card,
 	return 0;
 }
 
+int qeth_stop_channel(struct qeth_channel *channel)
+{
+	struct ccw_device *cdev = channel->ccwdev;
+	int rc;
+
+	rc = ccw_device_set_offline(cdev);
+
+	spin_lock_irq(get_ccwdev_lock(cdev));
+	if (channel->active_cmd) {
+		dev_err(&cdev->dev, "Stopped channel while cmd %px was still active\n",
+			channel->active_cmd);
+		channel->active_cmd = NULL;
+	}
+	spin_unlock_irq(get_ccwdev_lock(cdev));
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(qeth_stop_channel);
+
 static int qeth_halt_channels(struct qeth_card *card)
 {
 	int rc1 = 0, rc2 = 0, rc3 = 0;
@@ -1746,6 +1775,8 @@ static int qeth_send_control_data(struct qeth_card *card,
 	spin_lock_irq(get_ccwdev_lock(channel->ccwdev));
 	rc = ccw_device_start_timeout(channel->ccwdev, __ccw_from_cmd(iob),
 				      (addr_t) iob, 0, 0, timeout);
+	if (!rc)
+		channel->active_cmd = iob;
 	spin_unlock_irq(get_ccwdev_lock(channel->ccwdev));
 	if (rc) {
 		QETH_DBF_MESSAGE(2, "qeth_send_control_data on device %x: ccw_device_start rc = %i\n",
@@ -4667,12 +4698,12 @@ EXPORT_SYMBOL_GPL(qeth_vm_request_mac);
 
 static void qeth_determine_capabilities(struct qeth_card *card)
 {
+	struct qeth_channel *channel = &card->data;
+	struct ccw_device *ddev = channel->ccwdev;
 	int rc;
-	struct ccw_device *ddev;
 	int ddev_offline = 0;
 
 	QETH_CARD_TEXT(card, 2, "detcapab");
-	ddev = CARD_DDEV(card);
 	if (!ddev->online) {
 		ddev_offline = 1;
 		rc = ccw_device_set_online(ddev);
@@ -4711,7 +4742,7 @@ static void qeth_determine_capabilities(struct qeth_card *card)
 
 out_offline:
 	if (ddev_offline == 1)
-		ccw_device_set_offline(ddev);
+		qeth_stop_channel(channel);
 out:
 	return;
 }
@@ -4911,9 +4942,9 @@ retry:
 		QETH_DBF_MESSAGE(2, "Retrying to do IDX activates on device %x.\n",
 				 CARD_DEVID(card));
 	rc = qeth_qdio_clear_card(card, !IS_IQD(card));
-	ccw_device_set_offline(CARD_DDEV(card));
-	ccw_device_set_offline(CARD_WDEV(card));
-	ccw_device_set_offline(CARD_RDEV(card));
+	qeth_stop_channel(&card->data);
+	qeth_stop_channel(&card->write);
+	qeth_stop_channel(&card->read);
 	qdio_free(CARD_DDEV(card));
 	rc = ccw_device_set_online(CARD_RDEV(card));
 	if (rc)