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Subject[patch 3/10] s390: deadlock in dasd_devmap.
[patch 3/10] s390: deadlock in dasd_devmap.

From: Horst Hummel <horst.hummel@de.ibm.com>

Reintroduce a read-only copy of the devmap features in the
device struct. This is necessary to solve a deadlock on
the dasd_devmap_lock which is acquired by dasd_get_features
called from the dasd tasklet. The current implementation of
devmap doesn't allow to call any devmap function from
interrupt or softirq context.

Signed-off-by: Horst Hummel <horst.hummel@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diffstat:
drivers/s390/block/dasd.c | 19 ++++++-------------
drivers/s390/block/dasd_devmap.c | 8 ++++++--
drivers/s390/block/dasd_genhd.c | 10 +++-------
drivers/s390/block/dasd_int.h | 3 ++-
drivers/s390/block/dasd_ioctl.c | 17 +++++------------
drivers/s390/block/dasd_proc.c | 8 ++------
6 files changed, 24 insertions(+), 41 deletions(-)

diff -urpN linux-2.6/drivers/s390/block/dasd.c linux-2.6-patched/drivers/s390/block/dasd.c
--- linux-2.6/drivers/s390/block/dasd.c 2005-08-29 01:41:01.000000000 +0200
+++ linux-2.6-patched/drivers/s390/block/dasd.c 2005-08-29 19:18:06.000000000 +0200
@@ -7,7 +7,7 @@
* Bugreports.to..: <Linux390@de.ibm.com>
* (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
*
- * $Revision: 1.165 $
+ * $Revision: 1.167 $
*/

#include <linux/config.h>
@@ -1131,17 +1131,13 @@ __dasd_process_blk_queue(struct dasd_dev
request_queue_t *queue;
struct request *req;
struct dasd_ccw_req *cqr;
- int nr_queued, feature_ro;
+ int nr_queued;

queue = device->request_queue;
/* No queue ? Then there is nothing to do. */
if (queue == NULL)
return;

- feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
- if (feature_ro < 0) /* no devmap */
- return;
-
/*
* We requeue request from the block device queue to the ccw
* queue only in two states. In state DASD_STATE_READY the
@@ -1162,7 +1158,8 @@ __dasd_process_blk_queue(struct dasd_dev
nr_queued < DASD_CHANQ_MAX_SIZE) {
req = elv_next_request(queue);

- if (feature_ro && rq_data_dir(req) == WRITE) {
+ if (device->features & DASD_FEATURE_READONLY &&
+ rq_data_dir(req) == WRITE) {
DBF_DEV_EVENT(DBF_ERR, device,
"Rejecting write request %p",
req);
@@ -1814,17 +1811,13 @@ dasd_generic_set_online (struct ccw_devi

{
struct dasd_device *device;
- int feature_diag, rc;
+ int rc;

device = dasd_create_device(cdev);
if (IS_ERR(device))
return PTR_ERR(device);

- feature_diag = dasd_get_feature(cdev, DASD_FEATURE_USEDIAG);
- if (feature_diag < 0)
- return feature_diag;
-
- if (feature_diag) {
+ if (device->features & DASD_FEATURE_USEDIAG) {
if (!dasd_diag_discipline_pointer) {
printk (KERN_WARNING
"dasd_generic couldn't online device %s "
diff -urpN linux-2.6/drivers/s390/block/dasd_devmap.c linux-2.6-patched/drivers/s390/block/dasd_devmap.c
--- linux-2.6/drivers/s390/block/dasd_devmap.c 2005-08-29 01:41:01.000000000 +0200
+++ linux-2.6-patched/drivers/s390/block/dasd_devmap.c 2005-08-29 19:18:06.000000000 +0200
@@ -11,7 +11,7 @@
* functions may not be called from interrupt context. In particular
* dasd_get_device is a no-no from interrupt context.
*
- * $Revision: 1.40 $
+ * $Revision: 1.43 $
*/

#include <linux/config.h>
@@ -513,6 +513,7 @@ dasd_create_device(struct ccw_device *cd
if (!devmap->device) {
devmap->device = device;
device->devindex = devmap->devindex;
+ device->features = devmap->features;
get_device(&cdev->dev);
device->cdev = cdev;
rc = 0;
@@ -643,6 +644,8 @@ dasd_ro_store(struct device *dev, struct
devmap->features |= DASD_FEATURE_READONLY;
else
devmap->features &= ~DASD_FEATURE_READONLY;
+ if (devmap->device)
+ devmap->device->features = devmap->features;
if (devmap->device && devmap->device->gdp)
set_disk_ro(devmap->device->gdp, ro_flag);
spin_unlock(&dasd_devmap_lock);
@@ -758,7 +761,8 @@ dasd_set_feature(struct ccw_device *cdev
devmap->features |= feature;
else
devmap->features &= ~feature;
-
+ if (devmap->device)
+ devmap->device->features = devmap->features;
spin_unlock(&dasd_devmap_lock);
return 0;
}
diff -urpN linux-2.6/drivers/s390/block/dasd_genhd.c linux-2.6-patched/drivers/s390/block/dasd_genhd.c
--- linux-2.6/drivers/s390/block/dasd_genhd.c 2005-08-29 01:41:01.000000000 +0200
+++ linux-2.6-patched/drivers/s390/block/dasd_genhd.c 2005-08-29 19:18:06.000000000 +0200
@@ -9,7 +9,7 @@
*
* gendisk related functions for the dasd driver.
*
- * $Revision: 1.50 $
+ * $Revision: 1.51 $
*/

#include <linux/config.h>
@@ -31,16 +31,12 @@ int
dasd_gendisk_alloc(struct dasd_device *device)
{
struct gendisk *gdp;
- int len, feature_ro;
+ int len;

/* Make sure the minor for this device exists. */
if (device->devindex >= DASD_PER_MAJOR)
return -EBUSY;

- feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
- if (feature_ro < 0)
- return feature_ro;
-
gdp = alloc_disk(1 << DASD_PARTN_BITS);
if (!gdp)
return -ENOMEM;
@@ -75,7 +71,7 @@ dasd_gendisk_alloc(struct dasd_device *d

sprintf(gdp->devfs_name, "dasd/%s", device->cdev->dev.bus_id);

- if (feature_ro)
+ if (device->features & DASD_FEATURE_READONLY)
set_disk_ro(gdp, 1);
gdp->private_data = device;
gdp->queue = device->request_queue;
diff -urpN linux-2.6/drivers/s390/block/dasd_int.h linux-2.6-patched/drivers/s390/block/dasd_int.h
--- linux-2.6/drivers/s390/block/dasd_int.h 2005-08-29 01:41:01.000000000 +0200
+++ linux-2.6-patched/drivers/s390/block/dasd_int.h 2005-08-29 19:18:06.000000000 +0200
@@ -6,7 +6,7 @@
* Bugreports.to..: <Linux390@de.ibm.com>
* (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999,2000
*
- * $Revision: 1.64 $
+ * $Revision: 1.65 $
*/

#ifndef DASD_INT_H
@@ -286,6 +286,7 @@ struct dasd_device {
unsigned int bp_block; /* bytes per block */
unsigned int s2b_shift; /* log2 (bp_block/512) */
unsigned long flags; /* per device flags */
+ unsigned short features; /* copy of devmap-features (read-only!) */

/* Device discipline stuff. */
struct dasd_discipline *discipline;
diff -urpN linux-2.6/drivers/s390/block/dasd_ioctl.c linux-2.6-patched/drivers/s390/block/dasd_ioctl.c
--- linux-2.6/drivers/s390/block/dasd_ioctl.c 2005-08-29 01:41:01.000000000 +0200
+++ linux-2.6-patched/drivers/s390/block/dasd_ioctl.c 2005-08-29 19:18:06.000000000 +0200
@@ -7,7 +7,7 @@
* Bugreports.to..: <Linux390@de.ibm.com>
* (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
*
- * $Revision: 1.45 $
+ * $Revision: 1.47 $
*
* i/o controls for the dasd driver.
*/
@@ -296,7 +296,6 @@ dasd_ioctl_format(struct block_device *b
{
struct dasd_device *device;
struct format_data_t fdata;
- int feature_ro;

if (!capable(CAP_SYS_ADMIN))
return -EACCES;
@@ -308,10 +307,7 @@ dasd_ioctl_format(struct block_device *b
if (device == NULL)
return -ENODEV;

- feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
- if (feature_ro < 0)
- return feature_ro;
- if (feature_ro)
+ if (device->features & DASD_FEATURE_READONLY)
return -EROFS;
if (copy_from_user(&fdata, (void __user *) args,
sizeof (struct format_data_t)))
@@ -384,7 +380,7 @@ dasd_ioctl_information(struct block_devi
struct dasd_device *device;
struct dasd_information2_t *dasd_info;
unsigned long flags;
- int rc, feature_ro;
+ int rc;
struct ccw_device *cdev;

device = bdev->bd_disk->private_data;
@@ -394,10 +390,6 @@ dasd_ioctl_information(struct block_devi
if (!device->discipline->fill_info)
return -EINVAL;

- feature_ro = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
- if (feature_ro < 0)
- return feature_ro;
-
dasd_info = kmalloc(sizeof(struct dasd_information2_t), GFP_KERNEL);
if (dasd_info == NULL)
return -ENOMEM;
@@ -427,7 +419,8 @@ dasd_ioctl_information(struct block_devi
(dasd_check_blocksize(device->bp_block)))
dasd_info->format = DASD_FORMAT_NONE;

- dasd_info->features |= feature_ro;
+ dasd_info->features |=
+ ((device->features & DASD_FEATURE_READONLY) != 0);

if (device->discipline)
memcpy(dasd_info->type, device->discipline->name, 4);
diff -urpN linux-2.6/drivers/s390/block/dasd_proc.c linux-2.6-patched/drivers/s390/block/dasd_proc.c
--- linux-2.6/drivers/s390/block/dasd_proc.c 2005-08-29 01:41:01.000000000 +0200
+++ linux-2.6-patched/drivers/s390/block/dasd_proc.c 2005-08-29 19:18:06.000000000 +0200
@@ -9,7 +9,7 @@
*
* /proc interface for the dasd driver.
*
- * $Revision: 1.32 $
+ * $Revision: 1.33 $
*/

#include <linux/config.h>
@@ -55,7 +55,6 @@ dasd_devices_show(struct seq_file *m, vo
{
struct dasd_device *device;
char *substr;
- int feature;

device = dasd_device_from_devindex((unsigned long) v - 1);
if (IS_ERR(device))
@@ -79,10 +78,7 @@ dasd_devices_show(struct seq_file *m, vo
else
seq_printf(m, " is ????????");
/* Print devices features. */
- feature = dasd_get_feature(device->cdev, DASD_FEATURE_READONLY);
- if (feature < 0)
- return 0;
- substr = feature ? "(ro)" : " ";
+ substr = (device->features & DASD_FEATURE_READONLY) ? "(ro)" : " ";
seq_printf(m, "%4s: ", substr);
/* Print device status information. */
switch ((device != NULL) ? device->state : -1) {
-
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