From: Hans-Joachim Picht <hpicht@redhat.com>
Date: Thu, 31 Jan 2008 11:22:40 +0100
Subject: [s390] cio: sense id works with partial hw response
Message-id: 20080131102240.GC16660@redhat.com
O-Subject: [RHEL5 U2 PATCH 3/4] s390 - cio: make sense id procedure work with partial hardware response
Bugzilla: 430787
RH-Acked-by: Pete Zaitcev <zaitcev@redhat.com>

Description
============

In some cases the current sense id procedure trips over incomplete
hardware responses. In these case, checking against the preset value
of 0xFFFF is not enough. More critically, the VM DIAG call will always be
considered to have provided data after such an incident, even if it was not
successful at all.

The solution is to always initialize the control unit data before doing a
sense id call. Check the condition code before considering the control unit
data. And initialize again, before evaluating the VM data.

Bugzilla
=========

BZ  430787
https://bugzilla.redhat.com/show_bug.cgi?id=430787

Upstream status of the patch:
=============================

Patch will go upstream within the next 7 days.

Test status:
============
Kernel with patch was built and successfully tested

Please ACK.

With best regards,

Hans

 drivers/s390/cio/device_id.c |  107 +++++++++++++++++++++++++-----------------
 1 files changed, 64 insertions(+), 43 deletions(-)

diff --git a/drivers/s390/cio/device_id.c b/drivers/s390/cio/device_id.c
index fdcc07f..890c4a2 100644
--- a/drivers/s390/cio/device_id.c
+++ b/drivers/s390/cio/device_id.c
@@ -24,17 +24,18 @@
 #include "device.h"
 #include "ioasm.h"
 
-/*
- * Input :
- *   devno - device number
- *   ps	   - pointer to sense ID data area
- * Output : none
+/**
+ * vm_vdev_to_cu_type() - Convert vm virtual device into control unit type
+ *                        for certain devices.
+ *  @class: virtual device class
+ *  @type:  virtual device type
+ *
+ *  Returns control unit type if a match was made or %0xffff otherwise.
  */
-static void
-VM_virtual_device_info (__u16 devno, struct senseid *ps)
+static int vm_vdev_to_cu_type (int class, int type)
 {
 	static struct {
-		int vrdcvcla, vrdcvtyp, cu_type;
+		int class, type, cu_type;
 	} vm_devices[] = {
 		{ 0x08, 0x01, 0x3480 },
 		{ 0x08, 0x02, 0x3430 },
@@ -66,8 +67,26 @@ VM_virtual_device_info (__u16 devno, struct senseid *ps)
 		{ 0x40, 0xc0, 0x5080 },
 		{ 0x80, 0x00, 0x3215 },
 	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vm_devices); i++)
+		if (class == vm_devices[i].class && type == vm_devices[i].type)
+			return vm_devices[i].cu_type;
+
+	return 0xffff;
+}
+
+/*
+ * Input :
+ *   devno - device number
+ *   ps	   - pointer to sense ID data area
+ * Output : none
+ */
+static int
+VM_virtual_device_info (u16 devno, struct senseid *ps)
+{
 	struct diag210 diag_data;
-	int ccode, i;
+	int ccode;
 
 	CIO_TRACE_EVENT (4, "VMvdinf");
 
@@ -77,21 +96,21 @@ VM_virtual_device_info (__u16 devno, struct senseid *ps)
 	};
 
 	ccode = diag210 (&diag_data);
-	ps->reserved = 0xff;
+	if ((ccode == 0) || (ccode == 2)) {
+		ps->reserved = 0xff;
 
-	/* Special case for bloody osa devices. */
-	if (diag_data.vrdcvcla == 0x02 &&
-	    diag_data.vrdcvtyp == 0x20) {
-		ps->cu_type = 0x3088;
-		ps->cu_model = 0x60;
-		return;
-	}
-	for (i = 0; i < sizeof(vm_devices) / sizeof(vm_devices[0]); i++)
-		if (diag_data.vrdcvcla == vm_devices[i].vrdcvcla &&
-		    diag_data.vrdcvtyp == vm_devices[i].vrdcvtyp) {
-			ps->cu_type = vm_devices[i].cu_type;
-			return;
+		/* Special case for bloody osa devices. */
+		if (diag_data.vrdcvcla == 0x02 && diag_data.vrdcvtyp == 0x20) {
+			ps->cu_type = 0x3088;
+			ps->cu_model = 0x60;
+			return 0;
 		}
+		ps->cu_type = vm_vdev_to_cu_type(diag_data.vrdcvcla,
+						diag_data.vrdcvtyp);
+		if (ps->cu_type != 0xffff)
+			return 0;
+	}
+
 	CIO_MSG_EVENT(0, "DIAG X'210' for device %04X returned (cc = %d):"
 		      "vdev class : %02X, vdev type : %04X \n ...  "
 		      "rdev class : %02X, rdev type : %04X, "
@@ -100,6 +119,8 @@ VM_virtual_device_info (__u16 devno, struct senseid *ps)
 		      diag_data.vrdcvcla, diag_data.vrdcvtyp,
 		      diag_data.vrdcrccl, diag_data.vrdccrty,
 		      diag_data.vrdccrmd);
+
+	return -ENODEV;
 }
 
 /*
@@ -128,6 +149,7 @@ __ccw_device_sense_id_start(struct ccw_device *cdev)
 	/* Try on every path. */
 	ret = -ENODEV;
 	while (cdev->private->imask != 0) {
+		cdev->private->senseid.cu_type = 0xFFFF;
 		if ((sch->opm & cdev->private->imask) != 0 &&
 		    cdev->private->iretry > 0) {
 			cdev->private->iretry--;
@@ -151,7 +173,6 @@ ccw_device_sense_id_start(struct ccw_device *cdev)
 	int ret;
 
 	memset (&cdev->private->senseid, 0, sizeof (struct senseid));
-	cdev->private->senseid.cu_type = 0xFFFF;
 	cdev->private->imask = 0x80;
 	cdev->private->iretry = 5;
 	ret = __ccw_device_sense_id_start(cdev);
@@ -171,13 +192,7 @@ ccw_device_check_sense_id(struct ccw_device *cdev)
 
 	sch = to_subchannel(cdev->dev.parent);
 	irb = &cdev->private->irb;
-	/* Did we get a proper answer ? */
-	if (cdev->private->senseid.cu_type != 0xFFFF && 
-	    cdev->private->senseid.reserved == 0xFF) {
-		if (irb->scsw.count < sizeof (struct senseid) - 8)
-			cdev->private->flags.esid = 1;
-		return 0; /* Success */
-	}
+
 	/* Check the error cases. */
 	if (irb->scsw.fctl & (SCSW_FCTL_HALT_FUNC | SCSW_FCTL_CLEAR_FUNC)) {
 		/* Retry Sense ID if requested. */
@@ -226,6 +241,15 @@ ccw_device_check_sense_id(struct ccw_device *cdev)
 				      sch->schid.sch_no);
 		return -EACCES;
 	}
+
+	/* Did we get a proper answer ? */
+	if (irb->scsw.cc == 0 && cdev->private->senseid.cu_type != 0xFFFF &&
+	    cdev->private->senseid.reserved == 0xFF) {
+		if (irb->scsw.count < sizeof (struct senseid) - 8)
+			cdev->private->flags.esid = 1;
+		return 0; /* Success */
+	}
+
 	/* Hmm, whatever happened, try again. */
 	CIO_MSG_EVENT(2, "SenseID : start_IO() for device %04x on "
 		      "subchannel 0.%x.%04x returns status %02X%02X\n",
@@ -277,20 +301,17 @@ ccw_device_sense_id_irq(struct ccw_device *cdev, enum dev_event dev_event)
 			break;
 		/* fall through. */
 	default:		/* Sense ID failed. Try asking VM. */
-		if (MACHINE_IS_VM) {
-			VM_virtual_device_info (cdev->private->devno,
+		if (MACHINE_IS_VM)
+			ret = VM_virtual_device_info (cdev->private->devno,
 						&cdev->private->senseid);
-			if (cdev->private->senseid.cu_type != 0xFFFF) {
-				/* Got the device information from VM. */
-				ccw_device_sense_id_done(cdev, 0);
-				return;
-			}
-		}
-		/*
-		 * If we can't couldn't identify the device type we
-		 *  consider the device "not operational".
-		 */
-		ccw_device_sense_id_done(cdev, -ENODEV);
+		else
+			/*
+			 * If we can't couldn't identify the device type we
+			 *  consider the device "not operational".
+			 */
+			ret = -ENODEV;
+
+		ccw_device_sense_id_done(cdev, ret);
 		break;
 	}
 }