[S390] cio: always query all paths on path verification.

Reappearing channel paths are sometimes not utilized by CCW devices
because path verification incorrectly relies on path-operational-mask
information which is not updated until a channel path has been used
again.
Modify path verification procedure to always query all available paths
to a device.

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

5 files changed, 68 insertions, 61 deletions

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index 9f9134b67e40..3bb4e472d73d 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -256,7 +256,7 @@ s390_subchannel_remove_chpid(struct device *dev, void *data)
         /* trigger path verification. */
         if (sch->driver && sch->driver->verify)
                 sch->driver->verify(&sch->dev);
-        else if (sch->vpm == mask)
+        else if (sch->lpm == mask)
                 goto out_unreg;
 out_unlock:
         spin_unlock_irq(&sch->lock);
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 54cce542a1ee..2e2882daefbb 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -569,10 +569,7 @@ cio_validate_subchannel (struct subchannel *sch, struct subchannel_id schid)
         sch->opm = 0xff;
         if (!cio_is_console(sch->schid))
                 chsc_validate_chpids(sch);
-        sch->lpm = sch->schib.pmcw.pim &
-                sch->schib.pmcw.pam &
-                sch->schib.pmcw.pom &
-                sch->opm;
+        sch->lpm = sch->schib.pmcw.pam & sch->opm;
 
         CIO_DEBUG(KERN_INFO, 0,
                   "Detected device %04x on subchannel 0.%x.%04X"
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index 7756f324fb6f..dace46fc32e8 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -232,10 +232,7 @@ ccw_device_recog_done(struct ccw_device *cdev, int state)
          */
         old_lpm = sch->lpm;
         stsch(sch->schid, &sch->schib);
-        sch->lpm = sch->schib.pmcw.pim &
-                sch->schib.pmcw.pam &
-                sch->schib.pmcw.pom &
-                sch->opm;
+        sch->lpm = sch->schib.pmcw.pam & sch->opm;
         /* Check since device may again have become not operational. */
         if (!sch->schib.pmcw.dnv)
                 state = DEV_STATE_NOT_OPER;
@@ -455,8 +452,8 @@ ccw_device_sense_pgid_done(struct ccw_device *cdev, int err)
                 return;
         }
         /* Start Path Group verification. */
-        sch->vpm = 0;   /* Start with no path groups set. */
         cdev->private->state = DEV_STATE_VERIFY;
+        cdev->private->flags.doverify = 0;
         ccw_device_verify_start(cdev);
 }
 
@@ -556,7 +553,19 @@ ccw_device_nopath_notify(void *data)
 void
 ccw_device_verify_done(struct ccw_device *cdev, int err)
 {
-        cdev->private->flags.doverify = 0;
+        struct subchannel *sch;
+
+        sch = to_subchannel(cdev->dev.parent);
+        /* Update schib - pom may have changed. */
+        stsch(sch->schid, &sch->schib);
+        /* Update lpm with verified path mask. */
+        sch->lpm = sch->vpm;
+        /* Repeat path verification? */
+        if (cdev->private->flags.doverify) {
+                cdev->private->flags.doverify = 0;
+                ccw_device_verify_start(cdev);
+                return;
+        }
         switch (err) {
         case -EOPNOTSUPP: /* path grouping not supported, just set online. */
                 cdev->private->options.pgroup = 0;
@@ -614,6 +623,7 @@ ccw_device_online(struct ccw_device *cdev)
         if (!cdev->private->options.pgroup) {
                 /* Start initial path verification. */
                 cdev->private->state = DEV_STATE_VERIFY;
+                cdev->private->flags.doverify = 0;
                 ccw_device_verify_start(cdev);
                 return 0;
         }
@@ -660,7 +670,6 @@ ccw_device_offline(struct ccw_device *cdev)
         /* Are we doing path grouping? */
         if (!cdev->private->options.pgroup) {
                 /* No, set state offline immediately. */
-                sch->vpm = 0;
                 ccw_device_done(cdev, DEV_STATE_OFFLINE);
                 return 0;
         }
@@ -781,6 +790,7 @@ ccw_device_online_verify(struct ccw_device *cdev, enum dev_event dev_event)
         }
         /* Device is idle, we can do the path verification. */
         cdev->private->state = DEV_STATE_VERIFY;
+        cdev->private->flags.doverify = 0;
         ccw_device_verify_start(cdev);
 }
 
@@ -1043,9 +1053,9 @@ ccw_device_wait4io_timeout(struct ccw_device *cdev, enum dev_event dev_event)
 }
 
 static void
-ccw_device_wait4io_verify(struct ccw_device *cdev, enum dev_event dev_event)
+ccw_device_delay_verify(struct ccw_device *cdev, enum dev_event dev_event)
 {
-        /* When the I/O has terminated, we have to start verification. */
+        /* Start verification after current task finished. */
         cdev->private->flags.doverify = 1;
 }
 
@@ -1111,10 +1121,7 @@ device_trigger_reprobe(struct subchannel *sch)
          * The pim, pam, pom values may not be accurate, but they are the best
          * we have before performing device selection :/
          */
-        sch->lpm = sch->schib.pmcw.pim &
-                sch->schib.pmcw.pam &
-                sch->schib.pmcw.pom &
-                sch->opm;
+        sch->lpm = sch->schib.pmcw.pam & sch->opm;
         /* Re-set some bits in the pmcw that were lost. */
         sch->schib.pmcw.isc = 3;
         sch->schib.pmcw.csense = 1;
@@ -1238,7 +1245,7 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_online_notoper,
                 [DEV_EVENT_INTERRUPT]   = ccw_device_verify_irq,
                 [DEV_EVENT_TIMEOUT]     = ccw_device_onoff_timeout,
-                [DEV_EVENT_VERIFY]      = ccw_device_nop,
+                [DEV_EVENT_VERIFY]      = ccw_device_delay_verify,
         },
         [DEV_STATE_ONLINE] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_online_notoper,
@@ -1281,7 +1288,7 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_online_notoper,
                 [DEV_EVENT_INTERRUPT]   = ccw_device_wait4io_irq,
                 [DEV_EVENT_TIMEOUT]     = ccw_device_wait4io_timeout,
-                [DEV_EVENT_VERIFY]      = ccw_device_wait4io_verify,
+                [DEV_EVENT_VERIFY]      = ccw_device_delay_verify,
         },
         [DEV_STATE_QUIESCE] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_quiesce_done,
@@ -1294,7 +1301,7 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_nop,
                 [DEV_EVENT_INTERRUPT]   = ccw_device_start_id,
                 [DEV_EVENT_TIMEOUT]     = ccw_device_bug,
-                [DEV_EVENT_VERIFY]      = ccw_device_nop,
+                [DEV_EVENT_VERIFY]      = ccw_device_start_id,
         },
         [DEV_STATE_DISCONNECTED_SENSE_ID] = {
                 [DEV_EVENT_NOTOPER]     = ccw_device_recog_notoper,
diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c
index acad8f852eda..93a897eebfff 100644
--- a/drivers/s390/cio/device_ops.c
+++ b/drivers/s390/cio/device_ops.c
@@ -256,7 +256,7 @@ ccw_device_get_path_mask(struct ccw_device *cdev)
         if (!sch)
                 return 0;
         else
-                return sch->vpm;
+                return sch->lpm;
 }
 
 static void
diff --git a/drivers/s390/cio/device_pgid.c b/drivers/s390/cio/device_pgid.c
index 1693a102dcfe..8ca2d078848c 100644
--- a/drivers/s390/cio/device_pgid.c
+++ b/drivers/s390/cio/device_pgid.c
@@ -245,18 +245,17 @@ __ccw_device_do_pgid(struct ccw_device *cdev, __u8 func)
         memset(&cdev->private->irb, 0, sizeof(struct irb));
 
         /* Try multiple times. */
-        ret = -ENODEV;
+        ret = -EACCES;
         if (cdev->private->iretry > 0) {
                 cdev->private->iretry--;
                 ret = cio_start (sch, cdev->private->iccws,
                                  cdev->private->imask);
-                /* ret is 0, -EBUSY, -EACCES or -ENODEV */
-                if ((ret != -EACCES) && (ret != -ENODEV))
+                /* We expect an interrupt in case of success or busy
+                 * indication. */
+                if ((ret == 0) || (ret == -EBUSY))
                         return ret;
         }
-        /* PGID command failed on this path. Switch it off. */
-        sch->lpm &= ~cdev->private->imask;
-        sch->vpm &= ~cdev->private->imask;
+        /* PGID command failed on this path. */
         CIO_MSG_EVENT(2, "SPID - Device %04x on Subchannel "
                       "0.%x.%04x, lpm %02X, became 'not operational'\n",
                       cdev->private->devno, sch->schid.ssid,
@@ -286,18 +285,17 @@ static int __ccw_device_do_nop(struct ccw_device *cdev)
         memset(&cdev->private->irb, 0, sizeof(struct irb));
 
         /* Try multiple times. */
-        ret = -ENODEV;
+        ret = -EACCES;
         if (cdev->private->iretry > 0) {
                 cdev->private->iretry--;
                 ret = cio_start (sch, cdev->private->iccws,
                                  cdev->private->imask);
-                /* ret is 0, -EBUSY, -EACCES or -ENODEV */
-                if ((ret != -EACCES) && (ret != -ENODEV))
+                /* We expect an interrupt in case of success or busy
+                 * indication. */
+                if ((ret == 0) || (ret == -EBUSY))
                         return ret;
         }
-        /* nop command failed on this path. Switch it off. */
-        sch->lpm &= ~cdev->private->imask;
-        sch->vpm &= ~cdev->private->imask;
+        /* nop command failed on this path. */
         CIO_MSG_EVENT(2, "NOP - Device %04x on Subchannel "
                       "0.%x.%04x, lpm %02X, became 'not operational'\n",
                       cdev->private->devno, sch->schid.ssid,
@@ -372,27 +370,32 @@ static void
 __ccw_device_verify_start(struct ccw_device *cdev)
 {
         struct subchannel *sch;
-        __u8 imask, func;
+        __u8 func;
         int ret;
 
         sch = to_subchannel(cdev->dev.parent);
-        while (sch->vpm != sch->lpm) {
-                /* Find first unequal bit in vpm vs. lpm */
-                for (imask = 0x80; imask != 0; imask >>= 1)
-                        if ((sch->vpm & imask) != (sch->lpm & imask))
-                                break;
-                cdev->private->imask = imask;
+        /* Repeat for all paths. */
+        for (; cdev->private->imask; cdev->private->imask >>= 1,
+                                     cdev->private->iretry = 5) {
+                if ((cdev->private->imask & sch->schib.pmcw.pam) == 0)
+                        /* Path not available, try next. */
+                        continue;
                 if (cdev->private->options.pgroup) {
-                        func = (sch->vpm & imask) ?
-                                SPID_FUNC_RESIGN : SPID_FUNC_ESTABLISH;
+                        if (sch->opm & cdev->private->imask)
+                                func = SPID_FUNC_ESTABLISH;
+                        else
+                                func = SPID_FUNC_RESIGN;
                         ret = __ccw_device_do_pgid(cdev, func);
                 } else
                         ret = __ccw_device_do_nop(cdev);
+                /* We expect an interrupt in case of success or busy
+                 * indication. */
                 if (ret == 0 || ret == -EBUSY)
                         return;
-                cdev->private->iretry = 5;
+                /* Permanent path failure, try next. */
         }
-        ccw_device_verify_done(cdev, (sch->lpm != 0) ? 0 : -ENODEV);
+        /* Done with all paths. */
+        ccw_device_verify_done(cdev, (sch->vpm != 0) ? 0 : -ENODEV);
 }
                 
 /*
@@ -421,14 +424,14 @@ ccw_device_verify_irq(struct ccw_device *cdev, enum dev_event dev_event)
         else
                 ret = __ccw_device_check_nop(cdev);
         memset(&cdev->private->irb, 0, sizeof(struct irb));
+
         switch (ret) {
         /* 0, -ETIME, -EAGAIN, -EOPNOTSUPP or -EACCES */
         case 0:
-                /* Establish or Resign Path Group done. Update vpm. */
-                if ((sch->lpm & cdev->private->imask) != 0)
-                        sch->vpm |= cdev->private->imask;
-                else
-                        sch->vpm &= ~cdev->private->imask;
+                /* Path verification ccw finished successfully, update lpm. */
+                sch->vpm |= sch->opm & cdev->private->imask;
+                /* Go on with next path. */
+                cdev->private->imask >>= 1;
                 cdev->private->iretry = 5;
                 __ccw_device_verify_start(cdev);
                 break;
@@ -441,6 +444,10 @@ ccw_device_verify_irq(struct ccw_device *cdev, enum dev_event dev_event)
                         cdev->private->options.pgroup = 0;
                 else
                         cdev->private->flags.pgid_single = 1;
+                /* Retry */
+                sch->vpm = 0;
+                cdev->private->imask = 0x80;
+                cdev->private->iretry = 5;
                 /* fall through. */
         case -EAGAIN:           /* Try again. */
                 __ccw_device_verify_start(cdev);
@@ -449,8 +456,7 @@ ccw_device_verify_irq(struct ccw_device *cdev, enum dev_event dev_event)
                 ccw_device_verify_done(cdev, -ETIME);
                 break;
         case -EACCES:           /* channel is not operational. */
-                sch->lpm &= ~cdev->private->imask;
-                sch->vpm &= ~cdev->private->imask;
+                cdev->private->imask >>= 1;
                 cdev->private->iretry = 5;
                 __ccw_device_verify_start(cdev);
                 break;
@@ -463,19 +469,17 @@ ccw_device_verify_start(struct ccw_device *cdev)
         struct subchannel *sch = to_subchannel(cdev->dev.parent);
 
         cdev->private->flags.pgid_single = 0;
+        cdev->private->imask = 0x80;
         cdev->private->iretry = 5;
-        /*
-         * Update sch->lpm with current values to catch paths becoming
-         * available again.
-         */
+
+        /* Start with empty vpm. */
+        sch->vpm = 0;
+
+        /* Get current pam. */
         if (stsch(sch->schid, &sch->schib)) {
                 ccw_device_verify_done(cdev, -ENODEV);
                 return;
         }
-        sch->lpm = sch->schib.pmcw.pim &
-                sch->schib.pmcw.pam &
-                sch->schib.pmcw.pom &
-                sch->opm;
         __ccw_device_verify_start(cdev);
 }
 
@@ -524,7 +528,6 @@ ccw_device_disband_irq(struct ccw_device *cdev, enum dev_event dev_event)
         switch (ret) {
         /* 0, -ETIME, -EAGAIN, -EOPNOTSUPP or -EACCES */
         case 0:                 /* disband successful. */
-                sch->vpm = 0;
                 ccw_device_disband_done(cdev, ret);
                 break;
         case -EOPNOTSUPP: