[S390] New DASD feature for ERP related logging

It is now possible to enable/disable ERP related logging without re-compile
and re-ipl. A additional sysfs-attribute 'erplog' allows to switch the
logging non-interruptive.

Signed-off-by: Horst Hummel <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/block/dasd.c

···
 		}
 	} else {		/* error */
 		memcpy(&cqr->irb, irb, sizeof (struct irb));
-#ifdef ERP_DEBUG
-		/* dump sense data */
-		dasd_log_sense(cqr, irb);
-#endif
+		if (device->features & DASD_FEATURE_ERPLOG) {
+			/* dump sense data */
+			dasd_log_sense(cqr, irb);
+		}
 		switch (era) {
 		case dasd_era_fatal:
 			cqr->status = DASD_CQR_FAILED;

drivers/s390/block/dasd_3990_erp.c

···
 	struct dasd_ccw_req *erp = NULL;
 	struct dasd_device *device = cqr->device;
 	__u32 cpa = cqr->irb.scsw.cpa;
+	struct dasd_ccw_req *temp_erp = NULL;
 
-#ifdef ERP_DEBUG
-	/* print current erp_chain */
-	DEV_MESSAGE(KERN_ERR, device, "%s",
-		    "ERP chain at BEGINNING of ERP-ACTION");
-	{
-		struct dasd_ccw_req *temp_erp = NULL;
-
+	if (device->features & DASD_FEATURE_ERPLOG) {
+		/* print current erp_chain */
+		DEV_MESSAGE(KERN_ERR, device, "%s",
+			    "ERP chain at BEGINNING of ERP-ACTION");
 		for (temp_erp = cqr;
 		     temp_erp != NULL; temp_erp = temp_erp->refers) {
 
···
 				    temp_erp->refers);
 		}
 	}
-#endif				/* ERP_DEBUG */
 
 	/* double-check if current erp/cqr was successfull */
 	if ((cqr->irb.scsw.cstat == 0x00) &&
···
 		erp = dasd_3990_erp_handle_match_erp(cqr, erp);
 	}
 
-#ifdef ERP_DEBUG
-	/* print current erp_chain */
-	DEV_MESSAGE(KERN_ERR, device, "%s", "ERP chain at END of ERP-ACTION");
-	{
-		struct dasd_ccw_req *temp_erp = NULL;
+	if (device->features & DASD_FEATURE_ERPLOG) {
+		/* print current erp_chain */
+		DEV_MESSAGE(KERN_ERR, device, "%s",
+			    "ERP chain at END of ERP-ACTION");
 		for (temp_erp = erp;
 		     temp_erp != NULL; temp_erp = temp_erp->refers) {
 
···
 				    temp_erp->refers);
 		}
 	}
-#endif				/* ERP_DEBUG */
 
 	if (erp->status == DASD_CQR_FAILED)
 		dasd_log_ccw(erp, 1, cpa);

drivers/s390/block/dasd_devmap.c

···
 			features |= DASD_FEATURE_READONLY;
 		else if (len == 4 && !strncmp(str, "diag", 4))
 			features |= DASD_FEATURE_USEDIAG;
+		else if (len == 6 && !strncmp(str, "erplog", 6))
+			features |= DASD_FEATURE_ERPLOG;
 		else {
 			MESSAGE(KERN_WARNING,
 				"unsupported feature: %*s, "
···
 }
 
 static DEVICE_ATTR(readonly, 0644, dasd_ro_show, dasd_ro_store);
+/*
+ * erplog controls the logging of ERP related data
+ * (e.g. failing channel programs).
+ */
+static ssize_t
+dasd_erplog_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dasd_devmap *devmap;
+	int erplog;
+
+	devmap = dasd_find_busid(dev->bus_id);
+	if (!IS_ERR(devmap))
+		erplog = (devmap->features & DASD_FEATURE_ERPLOG) != 0;
+	else
+		erplog = (DASD_FEATURE_DEFAULT & DASD_FEATURE_ERPLOG) != 0;
+	return snprintf(buf, PAGE_SIZE, erplog ? "1\n" : "0\n");
+}
+
+static ssize_t
+dasd_erplog_store(struct device *dev, struct device_attribute *attr,
+	      const char *buf, size_t count)
+{
+	struct dasd_devmap *devmap;
+	int val;
+	char *endp;
+
+	devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
+	if (IS_ERR(devmap))
+		return PTR_ERR(devmap);
+
+	val = simple_strtoul(buf, &endp, 0);
+	if (((endp + 1) < (buf + count)) || (val > 1))
+		return -EINVAL;
+
+	spin_lock(&dasd_devmap_lock);
+	if (val)
+		devmap->features |= DASD_FEATURE_ERPLOG;
+	else
+		devmap->features &= ~DASD_FEATURE_ERPLOG;
+	if (devmap->device)
+		devmap->device->features = devmap->features;
+	spin_unlock(&dasd_devmap_lock);
+	return count;
+}
+
+static DEVICE_ATTR(erplog, 0644, dasd_erplog_show, dasd_erplog_store);
 
 /*
  * use_diag controls whether the driver should use diag rather than ssch
···
 	&dev_attr_uid.attr,
 	&dev_attr_use_diag.attr,
 	&dev_attr_eer_enabled.attr,
+	&dev_attr_erplog.attr,
 	NULL,
 };
 

drivers/s390/block/dasd_int.h

···
 
 #ifdef __KERNEL__
 
-/* erp debugging in dasd.c and dasd_3990_erp.c */
-#define ERP_DEBUG
-
-
 /* we keep old device allocation scheme; IOW, minors are still in 0..255 */
 #define DASD_PER_MAJOR (1U << (MINORBITS - DASD_PARTN_BITS))
 #define DASD_PARTN_MASK ((1 << DASD_PARTN_BITS) - 1)

include/asm-s390/dasd.h

···
  * 0x01: readonly (ro)
  * 0x02: use diag discipline (diag)
  * 0x04: set the device initially online (internal use only)
+ * 0x08: enable ERP related logging
  */
 #define DASD_FEATURE_DEFAULT	     0x00
 #define DASD_FEATURE_READONLY	     0x01
 #define DASD_FEATURE_USEDIAG	     0x02
 #define DASD_FEATURE_INITIAL_ONLINE  0x04
+#define DASD_FEATURE_ERPLOG	     0x08
 
 #define DASD_PARTN_BITS 2