[S390] cio: unit check handling during internal I/O

Send unit checks that occur during internal I/O to the device driver
and react according to its return code.

Signed-off-by: Michael Ernst <mernst@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 25 insertions, 0 deletions

diff --git a/arch/s390/include/asm/ccwdev.h b/arch/s390/include/asm/ccwdev.h
index f4bd346a52d3..1c0030f9b890 100644
--- a/arch/s390/include/asm/ccwdev.h
+++ b/arch/s390/include/asm/ccwdev.h
@@ -91,6 +91,14 @@ struct ccw_device {
         void (*handler) (struct ccw_device *, unsigned long, struct irb *);
 };
 
+/*
+ * Possible CIO actions triggered by the unit check handler.
+ */
+enum uc_todo {
+        UC_TODO_RETRY,
+        UC_TODO_RETRY_ON_NEW_PATH,
+        UC_TODO_STOP
+};
 
 /**
  * struct ccw driver - device driver for channel attached devices
@@ -107,6 +115,7 @@ struct ccw_device {
  * @freeze: callback for freezing during hibernation snapshotting
  * @thaw: undo work done in @freeze
  * @restore: callback for restoring after hibernation
+ * @uc_handler: callback for unit check handler
  * @driver: embedded device driver structure
  * @name: device driver name
  */
@@ -124,6 +133,7 @@ struct ccw_driver {
         int (*freeze)(struct ccw_device *);
         int (*thaw) (struct ccw_device *);
         int (*restore)(struct ccw_device *);
+        enum uc_todo (*uc_handler) (struct ccw_device *, struct irb *);
         struct device_driver driver;
         char *name;
 };
diff --git a/drivers/s390/cio/ccwreq.c b/drivers/s390/cio/ccwreq.c
index 37df42af05ec..7f206ed44fdf 100644
--- a/drivers/s390/cio/ccwreq.c
+++ b/drivers/s390/cio/ccwreq.c
@@ -159,6 +159,7 @@ static enum io_status ccwreq_status(struct ccw_device *cdev, struct irb *lcirb)
 {
         struct irb *irb = &cdev->private->irb;
         struct cmd_scsw *scsw = &irb->scsw.cmd;
+        enum uc_todo todo;
 
         /* Perform BASIC SENSE if needed. */
         if (ccw_device_accumulate_and_sense(cdev, lcirb))
@@ -178,6 +179,20 @@ static enum io_status ccwreq_status(struct ccw_device *cdev, struct irb *lcirb)
                 /* Check for command reject. */
                 if (irb->ecw[0] & SNS0_CMD_REJECT)
                         return IO_REJECTED;
+                /* Ask the driver what to do */
+                if (cdev->drv && cdev->drv->uc_handler) {
+                        todo = cdev->drv->uc_handler(cdev, lcirb);
+                        switch (todo) {
+                        case UC_TODO_RETRY:
+                                return IO_STATUS_ERROR;
+                        case UC_TODO_RETRY_ON_NEW_PATH:
+                                return IO_PATH_ERROR;
+                        case UC_TODO_STOP:
+                                return IO_REJECTED;
+                        default:
+                                return IO_STATUS_ERROR;
+                        }
+                }
                 /* Assume that unexpected SENSE data implies an error. */
                 return IO_STATUS_ERROR;
         }