[patch 8/16] s390: channel tape fixes.
From: Martin Schwidefsky
Date: Tue Jun 21 2005 - 11:51:26 EST
[patch 8/16] s390: channel tape fixes.
From: Stefan Bader <shbader@xxxxxxxxxx>
Tape driver fixes:
- Added deferred condition handling to tape driver core.
- Added ability to handle busy conditions.
- Code cleanup.
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
diffstat:
drivers/s390/char/tape.h | 7
drivers/s390/char/tape_core.c | 299 ++++++++++++++++++++++++------------------
2 files changed, 181 insertions(+), 125 deletions(-)
diff -urpN linux-2.6/drivers/s390/char/tape_core.c linux-2.6-patched/drivers/s390/char/tape_core.c
--- linux-2.6/drivers/s390/char/tape_core.c 2005-06-21 17:36:39.000000000 +0200
+++ linux-2.6-patched/drivers/s390/char/tape_core.c 2005-06-21 17:36:50.000000000 +0200
@@ -3,11 +3,12 @@
* basic function of the tape device driver
*
* S390 and zSeries version
- * Copyright (C) 2001,2002 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ * Copyright (C) 2001,2005 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Carsten Otte <cotte@xxxxxxxxxx>
* Michael Holzheu <holzheu@xxxxxxxxxx>
* Tuan Ngo-Anh <ngoanh@xxxxxxxxxx>
* Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
+ * Stefan Bader <shbader@xxxxxxxxxx>
*/
#include <linux/config.h>
@@ -28,7 +29,7 @@
#define PRINTK_HEADER "TAPE_CORE: "
static void __tape_do_irq (struct ccw_device *, unsigned long, struct irb *);
-static void __tape_remove_request(struct tape_device *, struct tape_request *);
+static void tape_delayed_next_request(void * data);
/*
* One list to contain all tape devices of all disciplines, so
@@ -257,7 +258,7 @@ tape_med_state_set(struct tape_device *d
* Stop running ccw. Has to be called with the device lock held.
*/
static inline int
-__tape_halt_io(struct tape_device *device, struct tape_request *request)
+__tape_cancel_io(struct tape_device *device, struct tape_request *request)
{
int retries;
int rc;
@@ -270,20 +271,23 @@ __tape_halt_io(struct tape_device *devic
for (retries = 0; retries < 5; retries++) {
rc = ccw_device_clear(device->cdev, (long) request);
- if (rc == 0) { /* Termination successful */
- request->rc = -EIO;
- request->status = TAPE_REQUEST_DONE;
- return 0;
+ switch (rc) {
+ case 0:
+ request->status = TAPE_REQUEST_DONE;
+ return 0;
+ case -EBUSY:
+ request->status = TAPE_REQUEST_CANCEL;
+ schedule_work(&device->tape_dnr);
+ return 0;
+ case -ENODEV:
+ DBF_EXCEPTION(2, "device gone, retry\n");
+ break;
+ case -EIO:
+ DBF_EXCEPTION(2, "I/O error, retry\n");
+ break;
+ default:
+ BUG();
}
-
- if (rc == -ENODEV)
- DBF_EXCEPTION(2, "device gone, retry\n");
- else if (rc == -EIO)
- DBF_EXCEPTION(2, "I/O error, retry\n");
- else if (rc == -EBUSY)
- DBF_EXCEPTION(2, "device busy, retry late\n");
- else
- BUG();
}
return rc;
@@ -473,6 +477,7 @@ tape_alloc_device(void)
*device->modeset_byte = 0;
device->first_minor = -1;
atomic_set(&device->ref_count, 1);
+ INIT_WORK(&device->tape_dnr, tape_delayed_next_request, device);
return device;
}
@@ -708,54 +713,119 @@ tape_free_request (struct tape_request *
kfree(request);
}
+static inline int
+__tape_start_io(struct tape_device *device, struct tape_request *request)
+{
+ int rc;
+
+#ifdef CONFIG_S390_TAPE_BLOCK
+ if (request->op == TO_BLOCK)
+ device->discipline->check_locate(device, request);
+#endif
+ rc = ccw_device_start(
+ device->cdev,
+ request->cpaddr,
+ (unsigned long) request,
+ 0x00,
+ request->options
+ );
+ if (rc == 0) {
+ request->status = TAPE_REQUEST_IN_IO;
+ } else if (rc == -EBUSY) {
+ /* The common I/O subsystem is currently busy. Retry later. */
+ request->status = TAPE_REQUEST_QUEUED;
+ schedule_work(&device->tape_dnr);
+ rc = 0;
+ } else {
+ /* Start failed. Remove request and indicate failure. */
+ DBF_EVENT(1, "tape: start request failed with RC = %i\n", rc);
+ }
+ return rc;
+}
+
static inline void
-__tape_do_io_list(struct tape_device *device)
+__tape_start_next_request(struct tape_device *device)
{
struct list_head *l, *n;
struct tape_request *request;
int rc;
- DBF_LH(6, "__tape_do_io_list(%p)\n", device);
+ DBF_LH(6, "__tape_start_next_request(%p)\n", device);
/*
* Try to start each request on request queue until one is
* started successful.
*/
list_for_each_safe(l, n, &device->req_queue) {
request = list_entry(l, struct tape_request, list);
-#ifdef CONFIG_S390_TAPE_BLOCK
- if (request->op == TO_BLOCK)
- device->discipline->check_locate(device, request);
-#endif
- rc = ccw_device_start(device->cdev, request->cpaddr,
- (unsigned long) request, 0x00,
- request->options);
- if (rc == 0) {
- request->status = TAPE_REQUEST_IN_IO;
- break;
+
+ /*
+ * Avoid race condition if bottom-half was triggered more than
+ * once.
+ */
+ if (request->status == TAPE_REQUEST_IN_IO)
+ return;
+
+ /*
+ * We wanted to cancel the request but the common I/O layer
+ * was busy at that time. This can only happen if this
+ * function is called by delayed_next_request.
+ * Otherwise we start the next request on the queue.
+ */
+ if (request->status == TAPE_REQUEST_CANCEL) {
+ rc = __tape_cancel_io(device, request);
+ } else {
+ rc = __tape_start_io(device, request);
}
- /* Start failed. Remove request and indicate failure. */
- DBF_EVENT(1, "tape: DOIO failed with er = %i\n", rc);
+ if (rc == 0)
+ return;
- /* Set ending status and do callback. */
+ /* Set ending status. */
request->rc = rc;
request->status = TAPE_REQUEST_DONE;
- __tape_remove_request(device, request);
+
+ /* Remove from request queue. */
+ list_del(&request->list);
+
+ /* Do callback. */
+ if (request->callback != NULL)
+ request->callback(request, request->callback_data);
}
}
static void
-__tape_remove_request(struct tape_device *device, struct tape_request *request)
+tape_delayed_next_request(void *data)
{
- /* Remove from request queue. */
- list_del(&request->list);
+ struct tape_device * device;
- /* Do callback. */
- if (request->callback != NULL)
- request->callback(request, request->callback_data);
+ device = (struct tape_device *) data;
+ DBF_LH(6, "tape_delayed_next_request(%p)\n", device);
+ spin_lock_irq(get_ccwdev_lock(device->cdev));
+ __tape_start_next_request(device);
+ spin_unlock_irq(get_ccwdev_lock(device->cdev));
+}
+
+static inline void
+__tape_end_request(
+ struct tape_device * device,
+ struct tape_request * request,
+ int rc)
+{
+ DBF_LH(6, "__tape_end_request(%p, %p, %i)\n", device, request, rc);
+ if (request) {
+ request->rc = rc;
+ request->status = TAPE_REQUEST_DONE;
+
+ /* Remove from request queue. */
+ list_del(&request->list);
+
+ /* Do callback. */
+ if (request->callback != NULL)
+ request->callback(request, request->callback_data);
+ }
/* Start next request. */
if (!list_empty(&device->req_queue))
- __tape_do_io_list(device);
+ __tape_start_next_request(device);
}
/*
@@ -812,7 +882,7 @@ tape_dump_sense_dbf(struct tape_device *
* the device lock held.
*/
static inline int
-__tape_do_io(struct tape_device *device, struct tape_request *request)
+__tape_start_request(struct tape_device *device, struct tape_request *request)
{
int rc;
@@ -837,24 +907,16 @@ __tape_do_io(struct tape_device *device,
if (list_empty(&device->req_queue)) {
/* No other requests are on the queue. Start this one. */
-#ifdef CONFIG_S390_TAPE_BLOCK
- if (request->op == TO_BLOCK)
- device->discipline->check_locate(device, request);
-#endif
- rc = ccw_device_start(device->cdev, request->cpaddr,
- (unsigned long) request, 0x00,
- request->options);
- if (rc) {
- DBF_EVENT(1, "tape: DOIO failed with rc = %i\n", rc);
+ rc = __tape_start_io(device, request);
+ if (rc)
return rc;
- }
+
DBF_LH(5, "Request %p added for execution.\n", request);
list_add(&request->list, &device->req_queue);
- request->status = TAPE_REQUEST_IN_IO;
} else {
DBF_LH(5, "Request %p add to queue.\n", request);
- list_add_tail(&request->list, &device->req_queue);
request->status = TAPE_REQUEST_QUEUED;
+ list_add_tail(&request->list, &device->req_queue);
}
return 0;
}
@@ -872,7 +934,7 @@ tape_do_io_async(struct tape_device *dev
spin_lock_irq(get_ccwdev_lock(device->cdev));
/* Add request to request queue and try to start it. */
- rc = __tape_do_io(device, request);
+ rc = __tape_start_request(device, request);
spin_unlock_irq(get_ccwdev_lock(device->cdev));
return rc;
}
@@ -901,7 +963,7 @@ tape_do_io(struct tape_device *device, s
request->callback = __tape_wake_up;
request->callback_data = &wq;
/* Add request to request queue and try to start it. */
- rc = __tape_do_io(device, request);
+ rc = __tape_start_request(device, request);
spin_unlock_irq(get_ccwdev_lock(device->cdev));
if (rc)
return rc;
@@ -935,7 +997,7 @@ tape_do_io_interruptible(struct tape_dev
/* Setup callback */
request->callback = __tape_wake_up_interruptible;
request->callback_data = &wq;
- rc = __tape_do_io(device, request);
+ rc = __tape_start_request(device, request);
spin_unlock_irq(get_ccwdev_lock(device->cdev));
if (rc)
return rc;
@@ -944,36 +1006,27 @@ tape_do_io_interruptible(struct tape_dev
if (rc != -ERESTARTSYS)
/* Request finished normally. */
return request->rc;
+
/* Interrupted by a signal. We have to stop the current request. */
spin_lock_irq(get_ccwdev_lock(device->cdev));
- rc = __tape_halt_io(device, request);
+ rc = __tape_cancel_io(device, request);
+ spin_unlock_irq(get_ccwdev_lock(device->cdev));
if (rc == 0) {
+ /* Wait for the interrupt that acknowledges the halt. */
+ do {
+ rc = wait_event_interruptible(
+ wq,
+ (request->callback == NULL)
+ );
+ } while (rc != -ERESTARTSYS);
+
DBF_EVENT(3, "IO stopped on %08x\n", device->cdev_id);
rc = -ERESTARTSYS;
}
- spin_unlock_irq(get_ccwdev_lock(device->cdev));
return rc;
}
/*
- * Handle requests that return an i/o error in the irb.
- */
-static inline void
-tape_handle_killed_request(
- struct tape_device *device,
- struct tape_request *request)
-{
- if(request != NULL) {
- /* Set ending status. FIXME: Should the request be retried? */
- request->rc = -EIO;
- request->status = TAPE_REQUEST_DONE;
- __tape_remove_request(device, request);
- } else {
- __tape_do_io_list(device);
- }
-}
-
-/*
* Tape interrupt routine, called from the ccw_device layer
*/
static void
@@ -981,7 +1034,6 @@ __tape_do_irq (struct ccw_device *cdev,
{
struct tape_device *device;
struct tape_request *request;
- int final;
int rc;
device = (struct tape_device *) cdev->dev.driver_data;
@@ -996,12 +1048,13 @@ __tape_do_irq (struct ccw_device *cdev,
/* On special conditions irb is an error pointer */
if (IS_ERR(irb)) {
+ /* FIXME: What to do with the request? */
switch (PTR_ERR(irb)) {
case -ETIMEDOUT:
PRINT_WARN("(%s): Request timed out\n",
cdev->dev.bus_id);
case -EIO:
- tape_handle_killed_request(device, request);
+ __tape_end_request(device, request, -EIO);
break;
default:
PRINT_ERR("(%s): Unexpected i/o error %li\n",
@@ -1011,6 +1064,21 @@ __tape_do_irq (struct ccw_device *cdev,
return;
}
+ /*
+ * If the condition code is not zero and the start function bit is
+ * still set, this is an deferred error and the last start I/O did
+ * not succeed. Restart the request now.
+ */
+ if (irb->scsw.cc != 0 && (irb->scsw.fctl & SCSW_FCTL_START_FUNC)) {
+ PRINT_WARN("(%s): deferred cc=%i. restaring\n",
+ cdev->dev.bus_id,
+ irb->scsw.cc);
+ rc = __tape_start_io(device, request);
+ if (rc)
+ __tape_end_request(device, request, rc);
+ return;
+ }
+
/* May be an unsolicited irq */
if(request != NULL)
request->rescnt = irb->scsw.count;
@@ -1042,7 +1110,7 @@ __tape_do_irq (struct ccw_device *cdev,
* To detect these request the state will be set to TAPE_REQUEST_DONE.
*/
if(request != NULL && request->status == TAPE_REQUEST_DONE) {
- __tape_remove_request(device, request);
+ __tape_end_request(device, request, -EIO);
return;
}
@@ -1054,51 +1122,34 @@ __tape_do_irq (struct ccw_device *cdev,
* rc == TAPE_IO_RETRY: request finished but needs another go.
* rc == TAPE_IO_STOP: request needs to get terminated.
*/
- final = 0;
switch (rc) {
- case TAPE_IO_SUCCESS:
- /* Upon normal completion the device _is_ online */
- device->tape_generic_status |= GMT_ONLINE(~0);
- final = 1;
- break;
- case TAPE_IO_PENDING:
- break;
- case TAPE_IO_RETRY:
-#ifdef CONFIG_S390_TAPE_BLOCK
- if (request->op == TO_BLOCK)
- device->discipline->check_locate(device, request);
-#endif
- rc = ccw_device_start(cdev, request->cpaddr,
- (unsigned long) request, 0x00,
- request->options);
- if (rc) {
- DBF_EVENT(1, "tape: DOIO failed with er = %i\n", rc);
- final = 1;
- }
- break;
- case TAPE_IO_STOP:
- __tape_halt_io(device, request);
- break;
- default:
- if (rc > 0) {
- DBF_EVENT(6, "xunknownrc\n");
- PRINT_ERR("Invalid return code from discipline "
- "interrupt function.\n");
- rc = -EIO;
- }
- final = 1;
- break;
- }
- if (final) {
- /* May be an unsolicited irq */
- if(request != NULL) {
- /* Set ending status. */
- request->rc = rc;
- request->status = TAPE_REQUEST_DONE;
- __tape_remove_request(device, request);
- } else {
- __tape_do_io_list(device);
- }
+ case TAPE_IO_SUCCESS:
+ /* Upon normal completion the device _is_ online */
+ device->tape_generic_status |= GMT_ONLINE(~0);
+ __tape_end_request(device, request, rc);
+ break;
+ case TAPE_IO_PENDING:
+ break;
+ case TAPE_IO_RETRY:
+ rc = __tape_start_io(device, request);
+ if (rc)
+ __tape_end_request(device, request, rc);
+ break;
+ case TAPE_IO_STOP:
+ rc = __tape_cancel_io(device, request);
+ if (rc)
+ __tape_end_request(device, request, rc);
+ break;
+ default:
+ if (rc > 0) {
+ DBF_EVENT(6, "xunknownrc\n");
+ PRINT_ERR("Invalid return code from discipline "
+ "interrupt function.\n");
+ __tape_end_request(device, request, -EIO);
+ } else {
+ __tape_end_request(device, request, rc);
+ }
+ break;
}
}
@@ -1191,7 +1242,7 @@ tape_init (void)
#ifdef DBF_LIKE_HELL
debug_set_level(TAPE_DBF_AREA, 6);
#endif
- DBF_EVENT(3, "tape init: ($Revision: 1.51 $)\n");
+ DBF_EVENT(3, "tape init: ($Revision: 1.54 $)\n");
tape_proc_init();
tapechar_init ();
tapeblock_init ();
@@ -1216,7 +1267,7 @@ tape_exit(void)
MODULE_AUTHOR("(C) 2001 IBM Deutschland Entwicklung GmbH by Carsten Otte and "
"Michael Holzheu (cotte@xxxxxxxxxx,holzheu@xxxxxxxxxx)");
MODULE_DESCRIPTION("Linux on zSeries channel attached "
- "tape device driver ($Revision: 1.51 $)");
+ "tape device driver ($Revision: 1.54 $)");
MODULE_LICENSE("GPL");
module_init(tape_init);
diff -urpN linux-2.6/drivers/s390/char/tape.h linux-2.6-patched/drivers/s390/char/tape.h
--- linux-2.6/drivers/s390/char/tape.h 2005-06-17 21:48:29.000000000 +0200
+++ linux-2.6-patched/drivers/s390/char/tape.h 2005-06-21 17:36:50.000000000 +0200
@@ -3,10 +3,11 @@
* tape device driver for 3480/3490E/3590 tapes.
*
* S390 and zSeries version
- * Copyright (C) 2001,2002 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ * Copyright (C) 2001,2005 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Carsten Otte <cotte@xxxxxxxxxx>
* Tuan Ngo-Anh <ngoanh@xxxxxxxxxx>
* Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
+ * Stefan Bader <shbader@xxxxxxxxxx>
*/
#ifndef _TAPE_H
@@ -111,6 +112,7 @@ enum tape_request_status {
TAPE_REQUEST_QUEUED, /* request is queued to be processed */
TAPE_REQUEST_IN_IO, /* request is currently in IO */
TAPE_REQUEST_DONE, /* request is completed. */
+ TAPE_REQUEST_CANCEL, /* request should be canceled. */
};
/* Tape CCW request */
@@ -237,6 +239,9 @@ struct tape_device {
/* Block dev frontend data */
struct tape_blk_data blk_data;
#endif
+
+ /* Function to start or stop the next request later. */
+ struct work_struct tape_dnr;
};
/* Externals from tape_core.c */
-
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