[S390] cio: introduce cio_commit_config

To change the configuration of a subchannel we alter the modifiable
bits of the subchannel's schib field and issue a modify subchannel.
There can be the case that not all changes were applied -or worse-
quietly overwritten by the hardware. With the next store subchannel
we obtain the current state of the hardware but lose our target
configuration.

With this patch we introduce a subchannel_config structure which
contains the target subchannel configuration. Additionally the msch
wrapper cio_modify is replaced with cio_commit_config which
copies the desired changes to a temporary schib. msch is then
called with the temporary schib. This schib is only written back
to the subchannel if all changes were applied.

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

1 files changed, 73 insertions, 61 deletions

diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 9bdb463765c7..8f1cec499532 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -330,30 +330,70 @@ cio_cancel (struct subchannel *sch)
         }
 }
 
+
+static void cio_apply_config(struct subchannel *sch, struct schib *schib)
+{
+        schib->pmcw.intparm = sch->config.intparm;
+        schib->pmcw.mbi = sch->config.mbi;
+        schib->pmcw.isc = sch->config.isc;
+        schib->pmcw.ena = sch->config.ena;
+        schib->pmcw.mme = sch->config.mme;
+        schib->pmcw.mp = sch->config.mp;
+        schib->pmcw.csense = sch->config.csense;
+        schib->pmcw.mbfc = sch->config.mbfc;
+        if (sch->config.mbfc)
+                schib->mba = sch->config.mba;
+}
+
+static int cio_check_config(struct subchannel *sch, struct schib *schib)
+{
+        return (schib->pmcw.intparm == sch->config.intparm) &&
+                (schib->pmcw.mbi == sch->config.mbi) &&
+                (schib->pmcw.isc == sch->config.isc) &&
+                (schib->pmcw.ena == sch->config.ena) &&
+                (schib->pmcw.mme == sch->config.mme) &&
+                (schib->pmcw.mp == sch->config.mp) &&
+                (schib->pmcw.csense == sch->config.csense) &&
+                (schib->pmcw.mbfc == sch->config.mbfc) &&
+                (!sch->config.mbfc || (schib->mba == sch->config.mba));
+}
+
 /*
- * Function: cio_modify
- * Issues a "Modify Subchannel" on the specified subchannel
+ * cio_commit_config - apply configuration to the subchannel
  */
-int
-cio_modify (struct subchannel *sch)
+int cio_commit_config(struct subchannel *sch)
 {
-        int ccode, retry, ret;
+        struct schib schib;
+        int ccode, retry, ret = 0;
+
+        if (stsch(sch->schid, &schib) || !css_sch_is_valid(&schib))
+                return -ENODEV;
 
-        ret = 0;
         for (retry = 0; retry < 5; retry++) {
-                ccode = msch_err (sch->schid, &sch->schib);
-                if (ccode < 0)  /* -EIO if msch gets a program check. */
+                /* copy desired changes to local schib */
+                cio_apply_config(sch, &schib);
+                ccode = msch_err(sch->schid, &schib);
+                if (ccode < 0) /* -EIO if msch gets a program check. */
                         return ccode;
                 switch (ccode) {
                 case 0: /* successfull */
-                        return 0;
-                case 1: /* status pending */
+                        if (stsch(sch->schid, &schib) ||
+                            !css_sch_is_valid(&schib))
+                                return -ENODEV;
+                        if (cio_check_config(sch, &schib)) {
+                                /* commit changes from local schib */
+                                memcpy(&sch->schib, &schib, sizeof(schib));
+                                return 0;
+                        }
+                        ret = -EAGAIN;
+                        break;
+                case 1: /* status pending */
                         return -EBUSY;
-                case 2: /* busy */
-                        udelay (100);   /* allow for recovery */
+                case 2: /* busy */
+                        udelay(100); /* allow for recovery */
                         ret = -EBUSY;
                         break;
-                case 3: /* not operational */
+                case 3: /* not operational */
                         return -ENODEV;
                 }
         }
@@ -396,32 +436,24 @@ int cio_enable_subchannel(struct subchannel *sch, u32 intparm)
         if (cio_update_schib(sch))
                 return -ENODEV;
 
-        for (retry = 5, ret = 0; retry > 0; retry--) {
-                sch->schib.pmcw.ena = 1;
-                sch->schib.pmcw.isc = sch->isc;
-                sch->schib.pmcw.intparm = intparm;
-                ret = cio_modify(sch);
-                if (ret == -ENODEV)
-                        break;
-                if (ret == -EIO)
+        sch->config.ena = 1;
+        sch->config.isc = sch->isc;
+        sch->config.intparm = intparm;
+
+        for (retry = 0; retry < 3; retry++) {
+                ret = cio_commit_config(sch);
+                if (ret == -EIO) {
                         /*
-                         * Got a program check in cio_modify. Try without
+                         * Got a program check in msch. Try without
                          * the concurrent sense bit the next time.
                          */
-                        sch->schib.pmcw.csense = 0;
-                if (ret == 0) {
-                        if (cio_update_schib(sch)) {
-                                ret = -ENODEV;
-                                break;
-                        }
-                        if (sch->schib.pmcw.ena)
-                                break;
-                }
-                if (ret == -EBUSY) {
+                        sch->config.csense = 0;
+                } else if (ret == -EBUSY) {
                         struct irb irb;
                         if (tsch(sch->schid, &irb) != 0)
                                 break;
-                }
+                } else
+                        break;
         }
         sprintf (dbf_txt, "ret:%d", ret);
         CIO_TRACE_EVENT (2, dbf_txt);
@@ -436,7 +468,6 @@ EXPORT_SYMBOL_GPL(cio_enable_subchannel);
 int cio_disable_subchannel(struct subchannel *sch)
 {
         char dbf_txt[15];
-        int retry;
         int ret;
 
         CIO_TRACE_EVENT (2, "dissch");
@@ -454,27 +485,9 @@ int cio_disable_subchannel(struct subchannel *sch)
                  */
                 return -EBUSY;
 
-        for (retry = 5, ret = 0; retry > 0; retry--) {
-                sch->schib.pmcw.ena = 0;
-                ret = cio_modify(sch);
-                if (ret == -ENODEV)
-                        break;
-                if (ret == -EBUSY)
-                        /*
-                         * The subchannel is busy or status pending.
-                         * We'll disable when the next interrupt was delivered
-                         * via the state machine.
-                         */
-                        break;
-                if (ret == 0) {
-                        if (cio_update_schib(sch)) {
-                                ret = -ENODEV;
-                                break;
-                        }
-                        if (!sch->schib.pmcw.ena)
-                                break;
-                }
-        }
+        sch->config.ena = 0;
+        ret = cio_commit_config(sch);
+
         sprintf (dbf_txt, "ret:%d", ret);
         CIO_TRACE_EVENT (2, dbf_txt);
         return ret;
@@ -817,10 +830,9 @@ cio_probe_console(void)
          * enable console I/O-interrupt subclass
          */
         isc_register(CONSOLE_ISC);
-        console_subchannel.schib.pmcw.isc = CONSOLE_ISC;
-        console_subchannel.schib.pmcw.intparm =
-                (u32)(addr_t)&console_subchannel;
-        ret = cio_modify(&console_subchannel);
+        console_subchannel.config.isc = CONSOLE_ISC;
+        console_subchannel.config.intparm = (u32)(addr_t)&console_subchannel;
+        ret = cio_commit_config(&console_subchannel);
         if (ret) {
                 isc_unregister(CONSOLE_ISC);
                 console_subchannel_in_use = 0;
@@ -832,8 +844,8 @@ cio_probe_console(void)
 void
 cio_release_console(void)
 {
-        console_subchannel.schib.pmcw.intparm = 0;
-        cio_modify(&console_subchannel);
+        console_subchannel.config.intparm = 0;
+        cio_commit_config(&console_subchannel);
         isc_unregister(CONSOLE_ISC);
         console_subchannel_in_use = 0;
 }