[patch 36/52] [PATCH] cio: consistent infrastructure for internal I/O requests

Martin Schwidefsky
2009-11-13T15:11:39Z

[-- Attachment #1: 135-cio-internal-io.diff --]
[-- Type: text/plain, Size: 12286 bytes --]

From: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>

Reduce code duplication by introducing a central infrastructure to
perform an internal I/O operation on a CCW device.

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

drivers/s390/cio/Makefile | 2
drivers/s390/cio/ccwreq.c | 327 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/s390/cio/device.h | 8 +
drivers/s390/cio/io_sch.h | 50 +++++++
4 files changed, 386 insertions(+), 1 deletion(-)

Index: quilt-2.6/drivers/s390/cio/ccwreq.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ quilt-2.6/drivers/s390/cio/ccwreq.c 2009-11-13 16:08:19.000000000 +0100
@@ -0,0 +1,327 @@
+/*
+ * Handling of internal CCW device requests.
+ *
+ * Copyright IBM Corp. 2009
+ * Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/err.h>
+#include <asm/ccwdev.h>
+#include <asm/cio.h>
+
+#include "io_sch.h"
+#include "cio.h"
+#include "device.h"
+#include "cio_debug.h"
+
+/**
+ * lpm_adjust - adjust path mask
+ * @lpm: path mask to adjust
+ * @mask: mask of available paths
+ *
+ * Shift @lpm right until @lpm and @mask have at least one bit in common or
+ * until @lpm is zero. Return the resulting lpm.
+ */
+int lpm_adjust(int lpm, int mask)
+{
+ while (lpm && ((lpm & mask) == 0))
+ lpm >>= 1;
+ return lpm;
+}
+
+/*
+ * Adjust path mask to use next path and reset retry count. Return resulting
+ * path mask.
+ */
+static u16 ccwreq_next_path(struct ccw_device *cdev)
+{
+ struct ccw_request *req = &cdev->private->req;
+
+ req->retries = req->maxretries;
+ req->mask = lpm_adjust(req->mask >>= 1, req->lpm);
+
+ return req->mask;
+}
+
+/*
+ * Clean up device state and report to callback.
+ */
+static void ccwreq_stop(struct ccw_device *cdev, int rc)
+{
+ struct subchannel *sch = to_subchannel(cdev->dev.parent);
+ struct ccw_request *req = &cdev->private->req;
+
+ if (req->done)
+ return;
+ req->done = 1;
+ ccw_device_set_timeout(cdev, 0);
+ memset(&cdev->private->irb, 0, sizeof(struct irb));
+ sch->lpm = sch->schib.pmcw.pam;
+ if (rc && rc != -ENODEV && req->drc)
+ rc = req->drc;
+ req->callback(cdev, req->data, rc);
+}
+
+/*
+ * (Re-)Start the operation until retries and paths are exhausted.
+ */
+static void ccwreq_do(struct ccw_device *cdev)
+{
+ struct ccw_request *req = &cdev->private->req;
+ struct subchannel *sch = to_subchannel(cdev->dev.parent);
+ struct ccw1 *cp = req->cp;
+ int rc = -EACCES;
+
+ while (req->mask) {
+ if (req->retries-- == 0) {
+ /* Retries exhausted, try next path. */
+ ccwreq_next_path(cdev);
+ continue;
+ }
+ /* Perform start function. */
+ sch->lpm = 0xff;
+ memset(&cdev->private->irb, 0, sizeof(struct irb));
+ rc = cio_start(sch, cp, req->mask);
+ if (rc == 0) {
+ /* I/O started successfully. */
+ ccw_device_set_timeout(cdev, req->timeout);
+ return;
+ }
+ if (rc == -ENODEV) {
+ /* Permanent device error. */
+ break;
+ }
+ if (rc == -EACCES) {
+ /* Permant path error. */
+ ccwreq_next_path(cdev);
+ continue;
+ }
+ /* Temporary improper status. */
+ rc = cio_clear(sch);
+ if (rc)
+ break;
+ return;
+ }
+ ccwreq_stop(cdev, rc);
+}
+
+/**
+ * ccw_request_start - perform I/O request
+ * @cdev: ccw device
+ *
+ * Perform the I/O request specified by cdev->req.
+ */
+void ccw_request_start(struct ccw_device *cdev)
+{
+ struct ccw_request *req = &cdev->private->req;
+
+ req->mask = 0x80;
+ req->retries = req->maxretries;
+ req->mask = lpm_adjust(req->mask, req->lpm);
+ req->drc = 0;
+ req->done = 0;
+ req->cancel = 0;
+ if (!req->mask)
+ goto out_nopath;
+ ccwreq_do(cdev);
+ return;
+
+out_nopath:
+ ccwreq_stop(cdev, -EACCES);
+}
+
+/**
+ * ccw_request_cancel - cancel running I/O request
+ * @cdev: ccw device
+ *
+ * Cancel the I/O request specified by cdev->req. Return non-zero if request
+ * has already finished, zero otherwise.
+ */
+int ccw_request_cancel(struct ccw_device *cdev)
+{
+ struct subchannel *sch = to_subchannel(cdev->dev.parent);
+ struct ccw_request *req = &cdev->private->req;
+ int rc;
+
+ if (req->done)
+ return 1;
+ req->cancel = 1;
+ rc = cio_clear(sch);
+ if (rc)
+ ccwreq_stop(cdev, rc);
+ return 0;
+}
+
+/*
+ * Return the status of the internal I/O started on the specified ccw device.
+ * Perform BASIC SENSE if required.
+ */
+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;
+
+ /* Perform BASIC SENSE if needed. */
+ if (ccw_device_accumulate_and_sense(cdev, lcirb))
+ return IO_RUNNING;
+ /* Check for halt/clear interrupt. */
+ if (scsw->fctl & (SCSW_FCTL_HALT_FUNC | SCSW_FCTL_CLEAR_FUNC))
+ return IO_KILLED;
+ /* Check for path error. */
+ if (scsw->cc == 3 || scsw->pno)
+ return IO_PATH_ERROR;
+ /* Handle BASIC SENSE data. */
+ if (irb->esw.esw0.erw.cons) {
+ CIO_TRACE_EVENT(2, "sensedata");
+ CIO_HEX_EVENT(2, &cdev->private->dev_id,
+ sizeof(struct ccw_dev_id));
+ CIO_HEX_EVENT(2, &cdev->private->irb.ecw, SENSE_MAX_COUNT);
+ /* Check for command reject. */
+ if (irb->ecw[0] & SNS0_CMD_REJECT)
+ return IO_REJECTED;
+ /* Assume that unexpected SENSE data implies an error. */
+ return IO_STATUS_ERROR;
+ }
+ /* Check for channel errors. */
+ if (scsw->cstat != 0)
+ return IO_STATUS_ERROR;
+ /* Check for device errors. */
+ if (scsw->dstat & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
+ return IO_STATUS_ERROR;
+ /* Check for final state. */
+ if (!(scsw->dstat & DEV_STAT_DEV_END))
+ return IO_RUNNING;
+ /* Check for other improper status. */
+ if (scsw->cc == 1 && (scsw->stctl & SCSW_STCTL_ALERT_STATUS))
+ return IO_STATUS_ERROR;
+ return IO_DONE;
+}
+
+/*
+ * Log ccw request status.
+ */
+static void ccwreq_log_status(struct ccw_device *cdev, enum io_status status)
+{
+ struct ccw_request *req = &cdev->private->req;
+ struct {
+ struct ccw_dev_id dev_id;
+ u16 retries;
+ u8 lpm;
+ u8 status;
+ } __attribute__ ((packed)) data;
+ data.dev_id = cdev->private->dev_id;
+ data.retries = req->retries;
+ data.lpm = req->mask;
+ data.status = (u8) status;
+ CIO_TRACE_EVENT(2, "reqstat");
+ CIO_HEX_EVENT(2, &data, sizeof(data));
+}
+
+/**
+ * ccw_request_handler - interrupt handler for I/O request procedure.
+ * @cdev: ccw device
+ *
+ * Handle interrupt during I/O request procedure.
+ */
+void ccw_request_handler(struct ccw_device *cdev)
+{
+ struct ccw_request *req = &cdev->private->req;
+ struct irb *irb = (struct irb *) __LC_IRB;
+ enum io_status status;
+ int rc = -EOPNOTSUPP;
+
+ /* Check status of I/O request. */
+ status = ccwreq_status(cdev, irb);
+ if (req->filter)
+ status = req->filter(cdev, req->data, irb, status);
+ if (status != IO_RUNNING)
+ ccw_device_set_timeout(cdev, 0);
+ if (status != IO_DONE && status != IO_RUNNING)
+ ccwreq_log_status(cdev, status);
+ switch (status) {
+ case IO_DONE:
+ break;
+ case IO_RUNNING:
+ return;
+ case IO_REJECTED:
+ goto err;
+ case IO_PATH_ERROR:
+ goto out_next_path;
+ case IO_STATUS_ERROR:
+ goto out_restart;
+ case IO_KILLED:
+ /* Check if request was cancelled on purpose. */
+ if (req->cancel) {
+ rc = -EIO;
+ goto err;
+ }
+ goto out_restart;
+ }
+ /* Check back with request initiator. */
+ if (!req->check)
+ goto out;
+ switch (req->check(cdev, req->data)) {
+ case 0:
+ break;
+ case -EAGAIN:
+ goto out_restart;
+ case -EACCES:
+ goto out_next_path;
+ default:
+ goto err;
+ }
+out:
+ ccwreq_stop(cdev, 0);
+ return;
+
+out_next_path:
+ /* Try next path and restart I/O. */
+ if (!ccwreq_next_path(cdev)) {
+ rc = -EACCES;
+ goto err;
+ }
+out_restart:
+ /* Restart. */
+ ccwreq_do(cdev);
+ return;
+err:
+ ccwreq_stop(cdev, rc);
+}
+
+
+/**
+ * ccw_request_timeout - timeout handler for I/O request procedure
+ * @cdev: ccw device
+ *
+ * Handle timeout during I/O request procedure.
+ */
+void ccw_request_timeout(struct ccw_device *cdev)
+{
+ struct subchannel *sch = to_subchannel(cdev->dev.parent);
+ struct ccw_request *req = &cdev->private->req;
+ int rc;
+
+ if (!ccwreq_next_path(cdev)) {
+ /* set the final return code for this request */
+ req->drc = -ETIME;
+ }
+ rc = cio_clear(sch);
+ if (rc)
+ goto err;
+ return;
+
+err:
+ ccwreq_stop(cdev, rc);
+}
+
+/**
+ * ccw_request_notoper - notoper handler for I/O request procedure
+ * @cdev: ccw device
+ *
+ * Handle timeout during I/O request procedure.
+ */
+void ccw_request_notoper(struct ccw_device *cdev)
+{
+ ccwreq_stop(cdev, -ENODEV);
+}
Index: quilt-2.6/drivers/s390/cio/device.h
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/device.h 2009-11-13 16:08:18.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/device.h 2009-11-13 16:08:20.000000000 +0100
@@ -98,6 +98,14 @@
int ccw_device_accumulate_and_sense(struct ccw_device *, struct irb *);
int ccw_device_do_sense(struct ccw_device *, struct irb *);

+/* Function prototype for internal request handling. */
+int lpm_adjust(int lpm, int mask);
+void ccw_request_start(struct ccw_device *);
+int ccw_request_cancel(struct ccw_device *cdev);
+void ccw_request_handler(struct ccw_device *cdev);
+void ccw_request_timeout(struct ccw_device *cdev);
+void ccw_request_notoper(struct ccw_device *cdev);
+
/* Function prototypes for sense id stuff. */
void ccw_device_sense_id_start(struct ccw_device *);
void ccw_device_sense_id_irq(struct ccw_device *, enum dev_event);
Index: quilt-2.6/drivers/s390/cio/io_sch.h
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/io_sch.h 2009-11-13 16:08:18.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/io_sch.h 2009-11-13 16:08:20.000000000 +0100
@@ -1,7 +1,10 @@
#ifndef S390_IO_SCH_H
#define S390_IO_SCH_H

+#include <linux/types.h>
#include <asm/schid.h>
+#include <asm/ccwdev.h>
+#include "css.h"

/*
* command-mode operation request block
@@ -68,6 +71,52 @@
#define MAX_CIWS 8

/*
+ * Possible status values for a CCW request's I/O.
+ */
+enum io_status {
+ IO_DONE,
+ IO_RUNNING,
+ IO_STATUS_ERROR,
+ IO_PATH_ERROR,
+ IO_REJECTED,
+ IO_KILLED
+};
+
+/**
+ * ccw_request - Internal CCW request.
+ * @cp: channel program to start
+ * @timeout: maximum allowable time in jiffies between start I/O and interrupt
+ * @maxretries: number of retries per I/O operation and path
+ * @lpm: mask of paths to use
+ * @check: optional callback that determines if results are final
+ * @filter: optional callback to adjust request status based on IRB data
+ * @callback: final callback
+ * @data: user-defined pointer passed to all callbacks
+ * @mask: current path mask
+ * @retries: current number of retries
+ * @drc: delayed return code
+ * @cancel: non-zero if request was cancelled
+ * @done: non-zero if request was finished
+ */
+struct ccw_request {
+ struct ccw1 *cp;
+ unsigned long timeout;
+ u16 maxretries;
+ u8 lpm;
+ int (*check)(struct ccw_device *, void *);
+ enum io_status (*filter)(struct ccw_device *, void *, struct irb *,
+ enum io_status);
+ void (*callback)(struct ccw_device *, void *, int);
+ void *data;
+ /* These fields are used internally. */
+ u8 mask;
+ u16 retries;
+ int drc;
+ int cancel:1;
+ int done:1;
+} __attribute__((packed));
+
+/*
* sense-id response buffer layout
*/
struct senseid {
@@ -99,6 +148,7 @@
unsigned long registered;
struct ccw_dev_id dev_id; /* device id */
struct subchannel_id schid; /* subchannel number */
+ struct ccw_request req; /* internal I/O request */
u8 imask; /* lpm mask for SNID/SID/SPGID */
int iretry; /* retry counter SNID/SID/SPGID */
struct {
Index: quilt-2.6/drivers/s390/cio/Makefile
===================================================================
--- quilt-2.6.orig/drivers/s390/cio/Makefile 2009-11-13 15:48:33.000000000 +0100
+++ quilt-2.6/drivers/s390/cio/Makefile 2009-11-13 16:08:20.000000000 +0100
@@ -3,7 +3,7 @@
#

obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o isc.o \
- fcx.o itcw.o crw.o
+ fcx.o itcw.o crw.o ccwreq.o
ccw_device-objs += device.o device_fsm.o device_ops.o
ccw_device-objs += device_id.o device_pgid.o device_status.o
obj-y += ccw_device.o cmf.o