[patch 43/52] [PATCH] cio: make steal lock procedure more robust

[Martin Schwidefsky]

From: Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>

An Unconditional Reserve + Release operation (steal lock) for a
boxed device may fail when encountering special error cases
(e.g. unit checks or path errors). Fix this by using the more
robust ccw_request infrastructure for performing the steal lock
CCW program.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---

 drivers/s390/cio/device.h      |    4 +
 drivers/s390/cio/device_fsm.c  |   55 +++++++++-----------
 drivers/s390/cio/device_ops.c  |  112 +++++++++++++++++++----------------------
 drivers/s390/cio/device_pgid.c |   52 +++++++++++++++++++
 4 files changed, 134 insertions(+), 89 deletions(-)

Index: quilt-2.6/drivers/s390/cio/device_fsm.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device_fsm.c	2009-11-13 16:08:21.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device_fsm.c	2009-11-13 16:08:21.000000000 +0100
@@ -641,6 +641,23 @@
 }
 
 /*
+ * Handle path verification event in boxed state.
+ */
+static void ccw_device_boxed_verify(struct ccw_device *cdev,
+				    enum dev_event dev_event)
+{
+	struct subchannel *sch = to_subchannel(cdev->dev.parent);
+
+	if (cdev->online) {
+		if (cio_enable_subchannel(sch, (u32) (addr_t) sch))
+			ccw_device_done(cdev, DEV_STATE_NOT_OPER);
+		else
+			ccw_device_online_verify(cdev, dev_event);
+	} else
+		css_schedule_eval(sch->schid);
+}
+
+/*
  * Got an interrupt for a normal io (state online).
  */
 static void
@@ -817,32 +834,6 @@
 }
 
 static void
-ccw_device_stlck_done(struct ccw_device *cdev, enum dev_event dev_event)
-{
-	struct irb *irb;
-
-	switch (dev_event) {
-	case DEV_EVENT_INTERRUPT:
-		irb = (struct irb *) __LC_IRB;
-		/* Check for unsolicited interrupt. */
-		if ((scsw_stctl(&irb->scsw) ==
-		     (SCSW_STCTL_STATUS_PEND | SCSW_STCTL_ALERT_STATUS)) &&
-		    (!scsw_cc(&irb->scsw)))
-			/* FIXME: we should restart stlck here, but this
-			 * is extremely unlikely ... */
-			goto out_wakeup;
-
-		ccw_device_accumulate_irb(cdev, irb);
-		/* We don't care about basic sense etc. */
-		break;
-	default: /* timeout */
-		break;
-	}
-out_wakeup:
-	wake_up(&cdev->private->wait_q);
-}
-
-static void
 ccw_device_start_id(struct ccw_device *cdev, enum dev_event dev_event)
 {
 	struct subchannel *sch;
@@ -1010,9 +1001,9 @@
 	},
 	[DEV_STATE_BOXED] = {
 		[DEV_EVENT_NOTOPER]	= ccw_device_generic_notoper,
-		[DEV_EVENT_INTERRUPT]	= ccw_device_stlck_done,
-		[DEV_EVENT_TIMEOUT]	= ccw_device_stlck_done,
-		[DEV_EVENT_VERIFY]	= ccw_device_nop,
+		[DEV_EVENT_INTERRUPT]	= ccw_device_nop,
+		[DEV_EVENT_TIMEOUT]	= ccw_device_nop,
+		[DEV_EVENT_VERIFY]	= ccw_device_boxed_verify,
 	},
 	/* states to wait for i/o completion before doing something */
 	[DEV_STATE_TIMEOUT_KILL] = {
@@ -1052,6 +1043,12 @@
 		[DEV_EVENT_TIMEOUT]	= ccw_device_update_cmfblock,
 		[DEV_EVENT_VERIFY]	= ccw_device_update_cmfblock,
 	},
+	[DEV_STATE_STEAL_LOCK] = {
+		[DEV_EVENT_NOTOPER]	= ccw_device_request_event,
+		[DEV_EVENT_INTERRUPT]	= ccw_device_request_event,
+		[DEV_EVENT_TIMEOUT]	= ccw_device_request_event,
+		[DEV_EVENT_VERIFY]	= ccw_device_nop,
+	},
 };
 
 EXPORT_SYMBOL_GPL(ccw_device_set_timeout);
Index: quilt-2.6/drivers/s390/cio/device.h
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device.h	2009-11-13 16:08:21.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device.h	2009-11-13 16:08:21.000000000 +0100
@@ -28,6 +28,7 @@
 	DEV_STATE_DISCONNECTED_SENSE_ID,
 	DEV_STATE_CMFCHANGE,
 	DEV_STATE_CMFUPDATE,
+	DEV_STATE_STEAL_LOCK,
 	/* last element! */
 	NR_DEV_STATES
 };
@@ -116,6 +117,9 @@
 void ccw_device_disband_start(struct ccw_device *);
 void ccw_device_disband_done(struct ccw_device *, int);
 
+void ccw_device_stlck_start(struct ccw_device *, void *, void *, void *);
+void ccw_device_stlck_done(struct ccw_device *, void *, int);
+
 int ccw_device_call_handler(struct ccw_device *);
 
 int ccw_device_stlck(struct ccw_device *);
Index: quilt-2.6/drivers/s390/cio/device_ops.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device_ops.c	2009-11-13 16:08:21.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device_ops.c	2009-11-13 16:08:21.000000000 +0100
@@ -11,6 +11,7 @@
 #include <linux/list.h>
 #include <linux/device.h>
 #include <linux/delay.h>
+#include <linux/completion.h>
 
 #include <asm/ccwdev.h>
 #include <asm/idals.h>
@@ -504,74 +505,65 @@
 	return sch->lpm;
 }
 
-/*
- * Try to break the lock on a boxed device.
- */
-int
-ccw_device_stlck(struct ccw_device *cdev)
-{
-	void *buf, *buf2;
-	unsigned long flags;
-	struct subchannel *sch;
-	int ret;
+struct stlck_data {
+	struct completion done;
+	int rc;
+};
 
-	if (!cdev)
-		return -ENODEV;
+void ccw_device_stlck_done(struct ccw_device *cdev, void *data, int rc)
+{
+	struct stlck_data *sdata = data;
 
-	if (cdev->drv && !cdev->private->options.force)
-		return -EINVAL;
+	sdata->rc = rc;
+	complete(&sdata->done);
+}
 
-	sch = to_subchannel(cdev->dev.parent);
-	
-	CIO_TRACE_EVENT(2, "stl lock");
-	CIO_TRACE_EVENT(2, dev_name(&cdev->dev));
+/*
+ * Perform unconditional reserve + release.
+ */
+int ccw_device_stlck(struct ccw_device *cdev)
+{
+	struct subchannel *sch = to_subchannel(cdev->dev.parent);
+	struct stlck_data data;
+	u8 *buffer;
+	int rc;
 
-	buf = kmalloc(32*sizeof(char), GFP_DMA|GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-	buf2 = kmalloc(32*sizeof(char), GFP_DMA|GFP_KERNEL);
-	if (!buf2) {
-		kfree(buf);
-		return -ENOMEM;
+	/* Check if steal lock operation is valid for this device. */
+	if (cdev->drv) {
+		if (!cdev->private->options.force)
+			return -EINVAL;
 	}
-	spin_lock_irqsave(sch->lock, flags);
-	ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);
-	if (ret)
-		goto out_unlock;
-	/*
-	 * Setup ccw. We chain an unconditional reserve and a release so we
-	 * only break the lock.
-	 */
-	cdev->private->iccws[0].cmd_code = CCW_CMD_STLCK;
-	cdev->private->iccws[0].cda = (__u32) __pa(buf);
-	cdev->private->iccws[0].count = 32;
-	cdev->private->iccws[0].flags = CCW_FLAG_CC;
-	cdev->private->iccws[1].cmd_code = CCW_CMD_RELEASE;
-	cdev->private->iccws[1].cda = (__u32) __pa(buf2);
-	cdev->private->iccws[1].count = 32;
-	cdev->private->iccws[1].flags = 0;
-	ret = cio_start(sch, cdev->private->iccws, 0);
-	if (ret) {
-		cio_disable_subchannel(sch); //FIXME: return code?
+	buffer = kzalloc(64, GFP_DMA | GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+	init_completion(&data.done);
+	data.rc = -EIO;
+	spin_lock_irq(sch->lock);
+	rc = cio_enable_subchannel(sch, (u32) (addr_t) sch);
+	if (rc)
 		goto out_unlock;
+	/* Perform operation. */
+	cdev->private->state = DEV_STATE_STEAL_LOCK,
+	ccw_device_stlck_start(cdev, &data, &buffer[0], &buffer[32]);
+	spin_unlock_irq(sch->lock);
+	/* Wait for operation to finish. */
+	if (wait_for_completion_interruptible(&data.done)) {
+		/* Got a signal. */
+		spin_lock_irq(sch->lock);
+		ccw_request_cancel(cdev);
+		spin_unlock_irq(sch->lock);
+		wait_for_completion(&data.done);
 	}
-	cdev->private->irb.scsw.cmd.actl |= SCSW_ACTL_START_PEND;
-	spin_unlock_irqrestore(sch->lock, flags);
-	wait_event(cdev->private->wait_q,
-		   cdev->private->irb.scsw.cmd.actl == 0);
-	spin_lock_irqsave(sch->lock, flags);
-	cio_disable_subchannel(sch); //FIXME: return code?
-	if ((cdev->private->irb.scsw.cmd.dstat !=
-	     (DEV_STAT_CHN_END|DEV_STAT_DEV_END)) ||
-	    (cdev->private->irb.scsw.cmd.cstat != 0))
-		ret = -EIO;
-	/* Clear irb. */
-	memset(&cdev->private->irb, 0, sizeof(struct irb));
+	rc = data.rc;
+	/* Check results. */
+	spin_lock_irq(sch->lock);
+	cio_disable_subchannel(sch);
+	cdev->private->state = DEV_STATE_BOXED;
 out_unlock:
-	kfree(buf);
-	kfree(buf2);
-	spin_unlock_irqrestore(sch->lock, flags);
-	return ret;
+	spin_unlock_irq(sch->lock);
+	kfree(buffer);
+
+	return rc;
 }
 
 void *ccw_device_get_chp_desc(struct ccw_device *cdev, int chp_no)
Index: quilt-2.6/drivers/s390/cio/device_pgid.c
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device_pgid.c	2009-11-13 16:08:21.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device_pgid.c	2009-11-13 16:08:21.000000000 +0100
@@ -507,3 +507,55 @@
 	spid_build_cp(cdev, fn);
 	ccw_request_start(cdev);
 }
+
+static void stlck_build_cp(struct ccw_device *cdev, void *buf1, void *buf2)
+{
+	struct ccw_request *req = &cdev->private->req;
+	struct ccw1 *cp = cdev->private->iccws;
+
+	cp[0].cmd_code = CCW_CMD_STLCK;
+	cp[0].cda = (u32) (addr_t) buf1;
+	cp[0].count = 32;
+	cp[0].flags = CCW_FLAG_CC;
+	cp[1].cmd_code = CCW_CMD_RELEASE;
+	cp[1].cda = (u32) (addr_t) buf2;
+	cp[1].count = 32;
+	cp[1].flags = 0;
+	req->cp = cp;
+}
+
+static void stlck_callback(struct ccw_device *cdev, void *data, int rc)
+{
+	ccw_device_stlck_done(cdev, data, rc);
+}
+
+/**
+ * ccw_device_stlck_start - perform unconditional release
+ * @cdev: ccw device
+ * @data: data pointer to be passed to ccw_device_stlck_done
+ * @buf1: data pointer used in channel program
+ * @buf2: data pointer used in channel program
+ *
+ * Execute a channel program on @cdev to release an existing PGID reservation.
+ * When finished, call ccw_device_stlck_done with a return code specifying the
+ * result.
+ */
+void ccw_device_stlck_start(struct ccw_device *cdev, void *data, void *buf1,
+			    void *buf2)
+{
+	struct subchannel *sch = to_subchannel(cdev->dev.parent);
+	struct ccw_request *req = &cdev->private->req;
+
+	CIO_TRACE_EVENT(4, "stlck");
+	CIO_HEX_EVENT(4, &cdev->private->dev_id, sizeof(cdev->private->dev_id));
+	/* Request setup. */
+	memset(req, 0, sizeof(*req));
+	req->timeout	= PGID_TIMEOUT;
+	req->maxretries	= PGID_RETRIES;
+	req->lpm	= sch->schib.pmcw.pam & sch->opm;
+	req->data	= data;
+	req->callback	= stlck_callback;
+	stlck_build_cp(cdev, buf1, buf2);
+	ccw_request_start(cdev);
+}
+

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