s390/qeth: unify the tracking of active cmds on ccw device

We have one field to track _whether_ a cmd is active on a ccw device
('irq_pending'), and one to track _which_ cmd it is ('active_cmd').

Get rid of the irq_pending field, by testing active_cmd for NULL.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core.h

@@ -614,7 +614,6 @@ struct qeth_channel {
 	struct ccw_device *ccwdev;
 	struct qeth_cmd_buffer *active_cmd;
 	enum qeth_channel_states state;
-	atomic_t irq_pending;
 };
 
 struct qeth_reply {
@@ -664,11 +663,6 @@ static inline struct ccw1 *__ccw_from_cmd(struct qeth_cmd_buffer *iob)
 	return (struct ccw1 *)(iob->data + ALIGN(iob->length, 8));
 }
 
-static inline bool qeth_trylock_channel(struct qeth_channel *channel)
-{
-	return atomic_cmpxchg(&channel->irq_pending, 0, 1) == 0;
-}
-
 /**
  *  OSA card related definitions
  */
@@ -896,10 +890,16 @@ static inline bool qeth_use_tx_irqs(struct qeth_card *card)
 static inline void qeth_unlock_channel(struct qeth_card *card,
 				       struct qeth_channel *channel)
 {
-	atomic_set(&channel->irq_pending, 0);
+	xchg(&channel->active_cmd, NULL);
 	wake_up(&card->wait_q);
 }
 
+static inline bool qeth_trylock_channel(struct qeth_channel *channel,
+					struct qeth_cmd_buffer *cmd)
+{
+	return cmpxchg(&channel->active_cmd, NULL, cmd) == NULL;
+}
+
 struct qeth_trap_id {
 	__u16 lparnr;
 	char vmname[8];

drivers/s390/net/qeth_core_main.c

@@ -1268,7 +1268,6 @@ static void qeth_irq(struct ccw_device *cdev, unsigned long intparm,
 		iob = (struct qeth_cmd_buffer *) (addr_t)intparm;
 	}
 
-	channel->active_cmd = NULL;
 	qeth_unlock_channel(card, channel);
 
 	rc = qeth_check_irb_error(card, cdev, irb);
@@ -1715,11 +1714,10 @@ static int qeth_stop_channel(struct qeth_channel *channel)
 	rc = ccw_device_set_offline(cdev);
 
 	spin_lock_irq(get_ccwdev_lock(cdev));
-	if (channel->active_cmd) {
+	if (channel->active_cmd)
 		dev_err(&cdev->dev, "Stopped channel while cmd %px was still active\n",
 			channel->active_cmd);
-		channel->active_cmd = NULL;
-	}
+
 	cdev->handler = NULL;
 	spin_unlock_irq(get_ccwdev_lock(cdev));
 
@@ -1732,7 +1730,7 @@ static int qeth_start_channel(struct qeth_channel *channel)
 	int rc;
 
 	channel->state = CH_STATE_DOWN;
-	atomic_set(&channel->irq_pending, 0);
+	xchg(&channel->active_cmd, NULL);
 
 	spin_lock_irq(get_ccwdev_lock(cdev));
 	cdev->handler = qeth_irq;
@@ -2039,7 +2037,7 @@ static int qeth_send_control_data(struct qeth_card *card,
 	reply->param = reply_param;
 
 	timeout = wait_event_interruptible_timeout(card->wait_q,
-						   qeth_trylock_channel(channel),
+						   qeth_trylock_channel(channel, iob),
 						   timeout);
 	if (timeout <= 0) {
 		qeth_put_cmd(iob);
@@ -2059,8 +2057,6 @@ 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",