s390: cio: introduce cio_cancel_halt_clear

For future code reuse purpose, this decouples the cio code with
the ccw device specific parts from ccw_device_cancel_halt_clear,
and makes a new common I/O interface named cio_cancel_halt_clear.

Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Message-Id: <20170317031743.40128-2-bjsdjshi@linux.vnet.ibm.com>
[CH: Fix typo]
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

drivers/s390/cio/cio.c

@@ -309,6 +309,65 @@ cio_cancel (struct subchannel *sch)
 	}
 }
 
+/**
+ * cio_cancel_halt_clear - Cancel running I/O by performing cancel, halt
+ * and clear ordinally if subchannel is valid.
+ * @sch: subchannel on which to perform the cancel_halt_clear operation
+ * @iretry: the number of the times remained to retry the next operation
+ *
+ * This should be called repeatedly since halt/clear are asynchronous
+ * operations. We do one try with cio_cancel, three tries with cio_halt,
+ * 255 tries with cio_clear. The caller should initialize @iretry with
+ * the value 255 for its first call to this, and keep using the same
+ * @iretry in the subsequent calls until it gets a non -EBUSY return.
+ *
+ * Returns 0 if device now idle, -ENODEV for device not operational,
+ * -EBUSY if an interrupt is expected (either from halt/clear or from a
+ * status pending), and -EIO if out of retries.
+ */
+int cio_cancel_halt_clear(struct subchannel *sch, int *iretry)
+{
+	int ret;
+
+	if (cio_update_schib(sch))
+		return -ENODEV;
+	if (!sch->schib.pmcw.ena)
+		/* Not operational -> done. */
+		return 0;
+	/* Stage 1: cancel io. */
+	if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_HALT_PEND) &&
+	    !(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
+		if (!scsw_is_tm(&sch->schib.scsw)) {
+			ret = cio_cancel(sch);
+			if (ret != -EINVAL)
+				return ret;
+		}
+		/*
+		 * Cancel io unsuccessful or not applicable (transport mode).
+		 * Continue with asynchronous instructions.
+		 */
+		*iretry = 3;	/* 3 halt retries. */
+	}
+	/* Stage 2: halt io. */
+	if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
+		if (*iretry) {
+			*iretry -= 1;
+			ret = cio_halt(sch);
+			if (ret != -EBUSY)
+				return (ret == 0) ? -EBUSY : ret;
+		}
+		/* Halt io unsuccessful. */
+		*iretry = 255;	/* 255 clear retries. */
+	}
+	/* Stage 3: clear io. */
+	if (*iretry) {
+		*iretry -= 1;
+		ret = cio_clear(sch);
+		return (ret == 0) ? -EBUSY : ret;
+	}
+	/* Function was unsuccessful */
+	return -EIO;
+}
 
 static void cio_apply_config(struct subchannel *sch, struct schib *schib)
 {

drivers/s390/cio/cio.h

@@ -123,6 +123,7 @@ extern int cio_enable_subchannel(struct subchannel *, u32);
 extern int cio_disable_subchannel (struct subchannel *);
 extern int cio_cancel (struct subchannel *);
 extern int cio_clear (struct subchannel *);
+extern int cio_cancel_halt_clear(struct subchannel *, int *);
 extern int cio_resume (struct subchannel *);
 extern int cio_halt (struct subchannel *);
 extern int cio_start (struct subchannel *, struct ccw1 *, __u8);

drivers/s390/cio/device_fsm.c

@@ -124,14 +124,6 @@ ccw_device_set_timeout(struct ccw_device *cdev, int expires)
 	add_timer(&cdev->private->timer);
 }
 
-/*
- * Cancel running i/o. This is called repeatedly since halt/clear are
- * asynchronous operations. We do one try with cio_cancel, two tries
- * with cio_halt, 255 tries with cio_clear. If everythings fails panic.
- * Returns 0 if device now idle, -ENODEV for device not operational and
- * -EBUSY if an interrupt is expected (either from halt/clear or from a
- * status pending).
- */
 int
 ccw_device_cancel_halt_clear(struct ccw_device *cdev)
 {
@@ -139,44 +131,14 @@ ccw_device_cancel_halt_clear(struct ccw_device *cdev)
 	int ret;
 
 	sch = to_subchannel(cdev->dev.parent);
-	if (cio_update_schib(sch))
-		return -ENODEV; 
-	if (!sch->schib.pmcw.ena)
-		/* Not operational -> done. */
-		return 0;
-	/* Stage 1: cancel io. */
-	if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_HALT_PEND) &&
-	    !(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
-		if (!scsw_is_tm(&sch->schib.scsw)) {
-			ret = cio_cancel(sch);
-			if (ret != -EINVAL)
-				return ret;
-		}
-		/* cancel io unsuccessful or not applicable (transport mode).
-		 * Continue with asynchronous instructions. */
-		cdev->private->iretry = 3;	/* 3 halt retries. */
-	}
-	if (!(scsw_actl(&sch->schib.scsw) & SCSW_ACTL_CLEAR_PEND)) {
-		/* Stage 2: halt io. */
-		if (cdev->private->iretry) {
-			cdev->private->iretry--;
-			ret = cio_halt(sch);
-			if (ret != -EBUSY)
-				return (ret == 0) ? -EBUSY : ret;
-		}
-		/* halt io unsuccessful. */
-		cdev->private->iretry = 255;	/* 255 clear retries. */
-	}
-	/* Stage 3: clear io. */
-	if (cdev->private->iretry) {
-		cdev->private->iretry--;
-		ret = cio_clear (sch);
-		return (ret == 0) ? -EBUSY : ret;
-	}
-	/* Function was unsuccessful */
-	CIO_MSG_EVENT(0, "0.%x.%04x: could not stop I/O\n",
-		      cdev->private->dev_id.ssid, cdev->private->dev_id.devno);
-	return -EIO;
+	ret = cio_cancel_halt_clear(sch, &cdev->private->iretry);
+
+	if (ret == -EIO)
+		CIO_MSG_EVENT(0, "0.%x.%04x: could not stop I/O\n",
+			      cdev->private->dev_id.ssid,
+			      cdev->private->dev_id.devno);
+
+	return ret;
 }
 
 void ccw_device_update_sense_data(struct ccw_device *cdev)