[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>

7 files changed, 123 insertions, 134 deletions

diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 9bdb463..8f1cec4 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;
 }
diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index fb125ef..5150fba 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -45,6 +45,19 @@ struct pmcw {
 				/*  ... in an operand exception.       */
 } __attribute__ ((packed));
 
+/* Target SCHIB configuration. */
+struct schib_config {
+	u64 mba;
+	u32 intparm;
+	u16 mbi;
+	u32 isc:3;
+	u32 ena:1;
+	u32 mme:2;
+	u32 mp:1;
+	u32 csense:1;
+	u32 mbfc:1;
+} __attribute__ ((packed));
+
 /*
  * subchannel information block
  */
@@ -83,6 +96,7 @@ struct subchannel {
 	struct css_driver *driver;
 	void *private; /* private per subchannel type data */
 	struct work_struct work;
+	struct schib_config config;
 } __attribute__ ((aligned(8)));
 
 #define IO_INTERRUPT_TYPE	   0 /* I/O interrupt type */
@@ -101,8 +115,8 @@ extern int cio_start_key (struct subchannel *, struct ccw1 *, __u8, __u8);
 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);
+extern int cio_commit_config(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 288482b..6ddd023 100644
--- a/drivers/s390/cio/cmf.c
+++ b/drivers/s390/cio/cmf.c
@@ -185,58 +185,19 @@ static inline void cmf_activate(void *area, unsigned int onoff)
 static int set_schib(struct ccw_device *cdev, u32 mme, int mbfc,
 		     unsigned long address)
 {
-	int ret;
-	int retry;
 	struct subchannel *sch;
-	struct schib *schib;
 
 	sch = to_subchannel(cdev->dev.parent);
-	schib = &sch->schib;
-	/* msch can silently fail, so do it again if necessary */
-	for (retry = 0; retry < 3; retry++) {
-		/* prepare 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 */
-		if (mbfc)
-			schib->mba = address;
-		else
-			schib->pmcw.mbi = address;
-
-		/* try to submit it */
-		switch(ret = msch_err(sch->schid, schib)) {
-			case 0:
-				break;
-			case 1:
-			case 2: /* in I/O or status pending */
-				ret = -EBUSY;
-				break;
-			case 3: /* subchannel is no longer valid */
-				ret = -ENODEV;
-				break;
-			default: /* msch caught an exception */
-				ret = -EINVAL;
-				break;
-		}
-		if (cio_update_schib(sch))
-			return -ENODEV;
-
-		if (ret)
-			break;
 
-		/* check if it worked */
-		if (schib->pmcw.mme  == mme &&
-		    schib->pmcw.mbfc == mbfc &&
-		    (mbfc ? (schib->mba == address)
-			  : (schib->pmcw.mbi == address)))
-			return 0;
+	sch->config.mme = mme;
+	sch->config.mbfc = mbfc;
+	/* address can be either a block address or a block index */
+	if (mbfc)
+		sch->config.mba = address;
+	else
+		sch->config.mbi = address;
 
-		ret = -EINVAL;
-	}
-
-	return ret;
+	return cio_commit_config(sch);
 }
 
 struct set_schib_struct {
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 76bbb1e..1b2d514 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -128,8 +128,8 @@ css_free_subchannel(struct subchannel *sch)
 {
 	if (sch) {
 		/* Reset intparm to zeroes. */
-		sch->schib.pmcw.intparm = 0;
-		cio_modify(sch);
+		sch->config.intparm = 0;
+		cio_commit_config(sch);
 		kfree(sch->lock);
 		kfree(sch);
 	}
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 51e9421..d312701 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1020,8 +1020,8 @@ static void ccw_device_call_sch_unregister(struct work_struct *work)
 	sch = to_subchannel(cdev->dev.parent);
 	css_sch_device_unregister(sch);
 	/* Reset intparm to zeroes. */
-	sch->schib.pmcw.intparm = 0;
-	cio_modify(sch);
+	sch->config.intparm = 0;
+	cio_commit_config(sch);
 	/* Release cdev reference for workqueue processing.*/
 	put_device(&cdev->dev);
 	/* Release subchannel reference for local processing. */
@@ -1148,8 +1148,8 @@ static void ccw_device_move_to_sch(struct work_struct *work)
 		spin_unlock_irq(former_parent->lock);
 		css_sch_device_unregister(former_parent);
 		/* Reset intparm to zeroes. */
-		former_parent->schib.pmcw.intparm = 0;
-		cio_modify(former_parent);
+		former_parent->config.intparm = 0;
+		cio_commit_config(former_parent);
 	}
 	sch_attach_device(sch, cdev);
 out:
@@ -1170,6 +1170,14 @@ static void io_subchannel_irq(struct subchannel *sch)
 		dev_fsm_event(cdev, DEV_EVENT_INTERRUPT);
 }
 
+void io_subchannel_init_config(struct subchannel *sch)
+{
+	memset(&sch->config, 0, sizeof(sch->config));
+	sch->config.csense = 1;
+	if ((sch->lpm & (sch->lpm - 1)) != 0)
+		sch->config.mp = 1;
+}
+
 static void io_subchannel_init_fields(struct subchannel *sch)
 {
 	if (cio_is_console(sch->schid))
@@ -1184,16 +1192,8 @@ static void io_subchannel_init_fields(struct subchannel *sch)
 		      sch->schib.pmcw.dev, sch->schid.ssid,
 		      sch->schid.sch_no, sch->schib.pmcw.pim,
 		      sch->schib.pmcw.pam, sch->schib.pmcw.pom);
-	/* Initially set up some fields in the pmcw. */
-	sch->schib.pmcw.ena = 0;
-	sch->schib.pmcw.csense = 1;	/* concurrent sense */
-	if ((sch->lpm & (sch->lpm - 1)) != 0)
-		sch->schib.pmcw.mp = 1; /* multipath mode */
-	/* clean up possible residual cmf stuff */
-	sch->schib.pmcw.mme = 0;
-	sch->schib.pmcw.mbfc = 0;
-	sch->schib.pmcw.mbi = 0;
-	sch->schib.mba = 0;
+
+	io_subchannel_init_config(sch);
 }
 
 static void io_subchannel_do_unreg(struct work_struct *work)
@@ -1203,8 +1203,8 @@ static void io_subchannel_do_unreg(struct work_struct *work)
 	sch = container_of(work, struct subchannel, work);
 	css_sch_device_unregister(sch);
 	/* Reset intparm to zeroes. */
-	sch->schib.pmcw.intparm = 0;
-	cio_modify(sch);
+	sch->config.intparm = 0;
+	cio_commit_config(sch);
 	put_device(&sch->dev);
 }
 
@@ -1680,8 +1680,8 @@ static int io_subchannel_sch_event(struct subchannel *sch, int slow)
 		spin_lock_irqsave(sch->lock, flags);
 
 		/* Reset intparm to zeroes. */
-		sch->schib.pmcw.intparm = 0;
-		cio_modify(sch);
+		sch->config.intparm = 0;
+		cio_commit_config(sch);
 		break;
 	case REPROBE:
 		ccw_device_trigger_reprobe(cdev);
diff --git a/drivers/s390/cio/device.h b/drivers/s390/cio/device.h
index 104ed66..0f2e63e 100644
--- a/drivers/s390/cio/device.h
+++ b/drivers/s390/cio/device.h
@@ -76,6 +76,7 @@ extern wait_queue_head_t ccw_device_init_wq;
 extern atomic_t ccw_device_init_count;
 
 void io_subchannel_recog_done(struct ccw_device *cdev);
+void io_subchannel_init_config(struct subchannel *sch);
 
 int ccw_device_cancel_halt_clear(struct ccw_device *);
 
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index e1a3786..9e24967 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -1026,11 +1026,12 @@ void ccw_device_trigger_reprobe(struct ccw_device *cdev)
 	 * we have before performing device selection :/
 	 */
 	sch->lpm = sch->schib.pmcw.pam & sch->opm;
-	/* Re-set some bits in the pmcw that were lost. */
-	sch->schib.pmcw.csense = 1;
-	sch->schib.pmcw.ena = 0;
-	if ((sch->lpm & (sch->lpm - 1)) != 0)
-		sch->schib.pmcw.mp = 1;
+	/*
+	 * Use the initial configuration since we can't be shure that the old
+	 * paths are valid.
+	 */
+	io_subchannel_init_config(sch);
+
 	/* We should also udate ssd info, but this has to wait. */
 	/* Check if this is another device which appeared on the same sch. */
 	if (sch->schib.pmcw.dev != cdev->private->dev_id.devno) {