[S390] cio: introduce cio_update_schib

There is the chance that we get condition code 0 for a stsch but
the resulting schib is not vaild. In the current code there are
2 cases:
* we do a check for validity of the schib after stsch, but at this
  time we have already stored the invaild schib in the subchannel
  structure. This may lead to problems.
* we don't do a check for validity, which is not that good either.

The patch addresses both issues by introducing the stsch wrapper
cio_update_schib which performs stsch on a local schib. This schib
is only written back to the subchannel if it's valid.

side note: For some functions (chp_events) the return codes are
different now (-ENXIO vs -ENODEV) but this shouldn't do harm
since the caller doesn't check for _specific_ errors.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

8 files changed, 67 insertions, 38 deletions

diff --git a/drivers/s390/cio/chsc_sch.c b/drivers/s390/cio/chsc_sch.c
index f49f0e502b8..0a2f2edafc0 100644
--- a/drivers/s390/cio/chsc_sch.c
+++ b/drivers/s390/cio/chsc_sch.c
@@ -61,7 +61,7 @@ static void chsc_subchannel_irq(struct subchannel *sch)
         }
         private->request = NULL;
         memcpy(&request->irb, irb, sizeof(*irb));
-        stsch(sch->schid, &sch->schib);
+        cio_update_schib(sch);
         complete(&request->completion);
         put_device(&sch->dev);
 }
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 8047800e9a0..9bdb463765c 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -114,11 +114,13 @@ cio_start_handle_notoper(struct subchannel *sch, __u8 lpm)
         else
                 sch->lpm = 0;
 
-        stsch (sch->schid, &sch->schib);
-
         CIO_MSG_EVENT(2, "cio_start: 'not oper' status for "
                       "subchannel 0.%x.%04x!\n", sch->schid.ssid,
                       sch->schid.sch_no);
+
+        if (cio_update_schib(sch))
+                return -ENODEV;
+
         sprintf(dbf_text, "no%s", dev_name(&sch->dev));
         CIO_TRACE_EVENT(0, dbf_text);
         CIO_HEX_EVENT(0, &sch->schib, sizeof (struct schib));
@@ -316,7 +318,8 @@ cio_cancel (struct subchannel *sch)
         switch (ccode) {
         case 0:         /* success */
                 /* Update information in scsw. */
-                stsch (sch->schid, &sch->schib);
+                if (cio_update_schib(sch))
+                        return -ENODEV;
                 return 0;
         case 1:         /* status pending */
                 return -EBUSY;
@@ -358,6 +361,23 @@ cio_modify (struct subchannel *sch)
 }
 
 /**
+ * cio_update_schib - Perform stsch and update schib if subchannel is valid.
+ * @sch: subchannel on which to perform stsch
+ * Return zero on success, -ENODEV otherwise.
+ */
+int cio_update_schib(struct subchannel *sch)
+{
+        struct schib schib;
+
+        if (stsch(sch->schid, &schib) || !css_sch_is_valid(&schib))
+                return -ENODEV;
+
+        memcpy(&sch->schib, &schib, sizeof(schib));
+        return 0;
+}
+EXPORT_SYMBOL_GPL(cio_update_schib);
+
+/**
  * cio_enable_subchannel - enable a subchannel.
  * @sch: subchannel to be enabled
  * @intparm: interruption parameter to set
@@ -365,7 +385,6 @@ cio_modify (struct subchannel *sch)
 int cio_enable_subchannel(struct subchannel *sch, u32 intparm)
 {
         char dbf_txt[15];
-        int ccode;
         int retry;
         int ret;
 
@@ -374,8 +393,7 @@ int cio_enable_subchannel(struct subchannel *sch, u32 intparm)
 
         if (sch_is_pseudo_sch(sch))
                 return -EINVAL;
-        ccode = stsch (sch->schid, &sch->schib);
-        if (ccode)
+        if (cio_update_schib(sch))
                 return -ENODEV;
 
         for (retry = 5, ret = 0; retry > 0; retry--) {
@@ -392,7 +410,10 @@ int cio_enable_subchannel(struct subchannel *sch, u32 intparm)
                          */
                         sch->schib.pmcw.csense = 0;
                 if (ret == 0) {
-                        stsch (sch->schid, &sch->schib);
+                        if (cio_update_schib(sch)) {
+                                ret = -ENODEV;
+                                break;
+                        }
                         if (sch->schib.pmcw.ena)
                                 break;
                 }
@@ -415,7 +436,6 @@ EXPORT_SYMBOL_GPL(cio_enable_subchannel);
 int cio_disable_subchannel(struct subchannel *sch)
 {
         char dbf_txt[15];
-        int ccode;
         int retry;
         int ret;
 
@@ -424,8 +444,7 @@ int cio_disable_subchannel(struct subchannel *sch)
 
         if (sch_is_pseudo_sch(sch))
                 return 0;
-        ccode = stsch (sch->schid, &sch->schib);
-        if (ccode == 3)         /* Not operational. */
+        if (cio_update_schib(sch))
                 return -ENODEV;
 
         if (scsw_actl(&sch->schib.scsw) != 0)
@@ -448,7 +467,10 @@ int cio_disable_subchannel(struct subchannel *sch)
                          */
                         break;
                 if (ret == 0) {
-                        stsch (sch->schid, &sch->schib);
+                        if (cio_update_schib(sch)) {
+                                ret = -ENODEV;
+                                break;
+                        }
                         if (!sch->schib.pmcw.ena)
                                 break;
                 }
@@ -851,7 +873,8 @@ __disable_subchannel_easy(struct subchannel_id schid, struct schib *schib)
                 cc = msch(schid, schib);
                 if (cc)
                         return (cc==3?-ENODEV:-EBUSY);
-                stsch(schid, schib);
+                if (stsch(schid, schib) || !css_sch_is_valid(schib))
+                        return -ENODEV;
                 if (!schib->pmcw.ena)
                         return 0;
         }
diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 5db887e8f03..fb125efd689 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -102,6 +102,7 @@ extern int cio_cancel (struct subchannel *);
 extern int cio_set_options (struct subchannel *, int);
 extern int cio_get_options (struct subchannel *);
 extern int cio_modify (struct subchannel *);
+extern int cio_update_schib(struct subchannel *sch);
 
 int cio_tm_start_key(struct subchannel *sch, struct tcw *tcw, u8 lpm, u8 key);
 int cio_tm_intrg(struct subchannel *sch);
diff --git a/drivers/s390/cio/cmf.c b/drivers/s390/cio/cmf.c
index a90b28c0be5..288482b2104 100644
--- a/drivers/s390/cio/cmf.c
+++ b/drivers/s390/cio/cmf.c
@@ -195,7 +195,8 @@ static int set_schib(struct ccw_device *cdev, u32 mme, int mbfc,
         /* msch can silently fail, so do it again if necessary */
         for (retry = 0; retry < 3; retry++) {
                 /* prepare schib */
-                stsch(sch->schid, schib);
+                if (cio_update_schib(sch))
+                        return -ENODEV;
                 schib->pmcw.mme  = mme;
                 schib->pmcw.mbfc = mbfc;
                 /* address can be either a block address or a block index */
@@ -219,7 +220,8 @@ static int set_schib(struct ccw_device *cdev, u32 mme, int mbfc,
                                 ret = -EINVAL;
                                 break;
                 }
-                stsch(sch->schid, schib); /* restore the schib */
+                if (cio_update_schib(sch))
+                        return -ENODEV;
 
                 if (ret)
                         break;
@@ -338,7 +340,7 @@ static int cmf_copy_block(struct ccw_device *cdev)
 
         sch = to_subchannel(cdev->dev.parent);
 
-        if (stsch(sch->schid, &sch->schib))
+        if (cio_update_schib(sch))
                 return -ENODEV;
 
         if (scsw_fctl(&sch->schib.scsw) & SCSW_FCTL_START_FUNC) {
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 868aa191538..51e94212bf6 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1350,10 +1350,7 @@ static void io_subchannel_verify(struct subchannel *sch)
 
 static int check_for_io_on_path(struct subchannel *sch, int mask)
 {
-        int cc;
-
-        cc = stsch(sch->schid, &sch->schib);
-        if (cc)
+        if (cio_update_schib(sch))
                 return 0;
         if (scsw_actl(&sch->schib.scsw) && sch->schib.pmcw.lpum == mask)
                 return 1;
@@ -1422,15 +1419,13 @@ static int io_subchannel_chp_event(struct subchannel *sch,
                 io_subchannel_verify(sch);
                 break;
         case CHP_OFFLINE:
-                if (stsch(sch->schid, &sch->schib))
-                        return -ENXIO;
-                if (!css_sch_is_valid(&sch->schib))
+                if (cio_update_schib(sch))
                         return -ENODEV;
                 io_subchannel_terminate_path(sch, mask);
                 break;
         case CHP_ONLINE:
-                if (stsch(sch->schid, &sch->schib))
-                        return -ENXIO;
+                if (cio_update_schib(sch))
+                        return -ENODEV;
                 sch->lpm |= mask & sch->opm;
                 io_subchannel_verify(sch);
                 break;
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index 01330cf5ae5..e1a3786779b 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -140,8 +140,7 @@ ccw_device_cancel_halt_clear(struct ccw_device *cdev)
         int ret;
 
         sch = to_subchannel(cdev->dev.parent);
-        ret = stsch(sch->schid, &sch->schib);
-        if (ret || !sch->schib.pmcw.dnv)
+        if (cio_update_schib(sch))
                 return -ENODEV; 
         if (!sch->schib.pmcw.ena)
                 /* Not operational -> done. */
@@ -245,11 +244,13 @@ ccw_device_recog_done(struct ccw_device *cdev, int state)
          * through ssch() and the path information is up to date.
          */
         old_lpm = sch->lpm;
-        stsch(sch->schid, &sch->schib);
-        sch->lpm = sch->schib.pmcw.pam & sch->opm;
+
         /* Check since device may again have become not operational. */
-        if (!sch->schib.pmcw.dnv)
+        if (cio_update_schib(sch))
                 state = DEV_STATE_NOT_OPER;
+        else
+                sch->lpm = sch->schib.pmcw.pam & sch->opm;
+
         if (cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID)
                 /* Force reprobe on all chpids. */
                 old_lpm = 0;
@@ -549,7 +550,11 @@ ccw_device_verify_done(struct ccw_device *cdev, int err)
 
         sch = to_subchannel(cdev->dev.parent);
         /* Update schib - pom may have changed. */
-        stsch(sch->schid, &sch->schib);
+        if (cio_update_schib(sch)) {
+                cdev->private->flags.donotify = 0;
+                ccw_device_done(cdev, DEV_STATE_NOT_OPER);
+                return;
+        }
         /* Update lpm with verified path mask. */
         sch->lpm = sch->vpm;
         /* Repeat path verification? */
@@ -667,7 +672,7 @@ ccw_device_offline(struct ccw_device *cdev)
                 return 0;
         }
         sch = to_subchannel(cdev->dev.parent);
-        if (stsch(sch->schid, &sch->schib) || !sch->schib.pmcw.dnv)
+        if (cio_update_schib(sch))
                 return -ENODEV;
         if (scsw_actl(&sch->schib.scsw) != 0)
                 return -EBUSY;
@@ -745,7 +750,10 @@ ccw_device_online_verify(struct ccw_device *cdev, enum dev_event dev_event)
          * Since we might not just be coming from an interrupt from the
          * subchannel we have to update the schib.
          */
-        stsch(sch->schid, &sch->schib);
+        if (cio_update_schib(sch)) {
+                ccw_device_verify_done(cdev, -ENODEV);
+                return;
+        }
 
         if (scsw_actl(&sch->schib.scsw) != 0 ||
             (scsw_stctl(&sch->schib.scsw) & SCSW_STCTL_STATUS_PEND) ||
@@ -1011,9 +1019,7 @@ void ccw_device_trigger_reprobe(struct ccw_device *cdev)
 
         sch = to_subchannel(cdev->dev.parent);
         /* Update some values. */
-        if (stsch(sch->schid, &sch->schib))
-                return;
-        if (!sch->schib.pmcw.dnv)
+        if (cio_update_schib(sch))
                 return;
         /*
          * The pim, pam, pom values may not be accurate, but they are the best
diff --git a/drivers/s390/cio/device_pgid.c b/drivers/s390/cio/device_pgid.c
index 86bc94eb607..fc5ca1dd52b 100644
--- a/drivers/s390/cio/device_pgid.c
+++ b/drivers/s390/cio/device_pgid.c
@@ -504,7 +504,7 @@ ccw_device_verify_start(struct ccw_device *cdev)
         sch->vpm = 0;
 
         /* Get current pam. */
-        if (stsch(sch->schid, &sch->schib)) {
+        if (cio_update_schib(sch)) {
                 ccw_device_verify_done(cdev, -ENODEV);
                 return;
         }
diff --git a/drivers/s390/cio/device_status.c b/drivers/s390/cio/device_status.c
index 1b03c5423be..5814dbee241 100644
--- a/drivers/s390/cio/device_status.c
+++ b/drivers/s390/cio/device_status.c
@@ -56,7 +56,8 @@ ccw_device_path_notoper(struct ccw_device *cdev)
         struct subchannel *sch;
 
         sch = to_subchannel(cdev->dev.parent);
-        stsch (sch->schid, &sch->schib);
+        if (cio_update_schib(sch))
+                goto doverify;
 
         CIO_MSG_EVENT(0, "%s(0.%x.%04x) - path(s) %02x are "
                       "not operational \n", __func__,
@@ -64,6 +65,7 @@ ccw_device_path_notoper(struct ccw_device *cdev)
                       sch->schib.pmcw.pnom);
 
         sch->lpm &= ~sch->schib.pmcw.pnom;
+doverify:
         cdev->private->flags.doverify = 1;
 }