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[S390] dasd deadlock after state change pending interrupt. 

The dasd_device_from_cdev function is called from interrupt context
to get the struct dasd_device associated with a ccw device. The
driver_data of the ccw device points to the dasd_devmap structure
which contains the pointer to the dasd_device structure. The lock
that protects the dasd_devmap structure is acquire with out irqsave.
To prevent the deadlock in dasd_device_from_cdev if it is called
from interrupt context the dependency to the dasd_devmap structure
needs to be removed. Let the driver_data of the ccw device point
to the dasd_device structure directly and use the ccw device lock
to protect the access.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2006-09-20 15:59:05 +02:00
parent 47addc84b4
commit a00bfd7147
3 changed files with 51 additions and 28 deletions
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4
drivers/s390/block/dasd.c
View File

@ -893,7 +893,7 @@ dasd_handle_killed_request(struct ccw_device *cdev, unsigned long intparm)
device = (struct dasd_device *) cqr->device;
if (device == NULL ||
device != dasd_device_from_cdev(cdev) ||
device != dasd_device_from_cdev_locked(cdev) ||
strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
MESSAGE(KERN_DEBUG, "invalid device in request: bus_id %s",
cdev->dev.bus_id);
@ -970,7 +970,7 @@ dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
/* first of all check for state change pending interrupt */
mask = DEV_STAT_ATTENTION | DEV_STAT_DEV_END | DEV_STAT_UNIT_EXCEP;
if ((irb->scsw.dstat & mask) == mask) {
device = dasd_device_from_cdev(cdev);
device = dasd_device_from_cdev_locked(cdev);
if (!IS_ERR(device)) {
dasd_handle_state_change_pending(device);
dasd_put_device(device);

74
drivers/s390/block/dasd_devmap.c
View File

@ -523,17 +523,17 @@ dasd_create_device(struct ccw_device *cdev)
{
struct dasd_devmap *devmap;
struct dasd_device *device;
unsigned long flags;
int rc;
devmap = dasd_devmap_from_cdev(cdev);
if (IS_ERR(devmap))
return (void *) devmap;
cdev->dev.driver_data = devmap;
device = dasd_alloc_device();
if (IS_ERR(device))
return device;
atomic_set(&device->ref_count, 2);
atomic_set(&device->ref_count, 3);
spin_lock(&dasd_devmap_lock);
if (!devmap->device) {
@ -552,6 +552,11 @@ dasd_create_device(struct ccw_device *cdev)
dasd_free_device(device);
return ERR_PTR(rc);
}
spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
cdev->dev.driver_data = device;
spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
return device;
}
@ -569,6 +574,7 @@ dasd_delete_device(struct dasd_device *device)
{
struct ccw_device *cdev;
struct dasd_devmap *devmap;
unsigned long flags;
/* First remove device pointer from devmap. */
devmap = dasd_find_busid(device->cdev->dev.bus_id);
@ -582,9 +588,16 @@ dasd_delete_device(struct dasd_device *device)
devmap->device = NULL;
spin_unlock(&dasd_devmap_lock);
/* Drop ref_count by 2, one for the devmap reference and
* one for the passed reference. */
atomic_sub(2, &device->ref_count);
/* Disconnect dasd_device structure from ccw_device structure. */
spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
device->cdev->dev.driver_data = NULL;
spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
/*
* Drop ref_count by 3, one for the devmap reference, one for
* the cdev reference and one for the passed reference.
*/
atomic_sub(3, &device->ref_count);
/* Wait for reference counter to drop to zero. */
wait_event(dasd_delete_wq, atomic_read(&device->ref_count) == 0);
@ -593,9 +606,6 @@ dasd_delete_device(struct dasd_device *device)
cdev = device->cdev;
device->cdev = NULL;
/* Disconnect dasd_devmap structure from ccw_device structure. */
cdev->dev.driver_data = NULL;
/* Put ccw_device structure. */
put_device(&cdev->dev);
@ -613,23 +623,34 @@ dasd_put_device_wake(struct dasd_device *device)
wake_up(&dasd_delete_wq);
}
/*
* Return dasd_device structure associated with cdev.
* This function needs to be called with the ccw device
* lock held. It can be used from interrupt context.
*/
struct dasd_device *
dasd_device_from_cdev_locked(struct ccw_device *cdev)
{
struct dasd_device *device = cdev->dev.driver_data;
if (!device)
return ERR_PTR(-ENODEV);
dasd_get_device(device);
return device;
}
/*
* Return dasd_device structure associated with cdev.
*/
struct dasd_device *
dasd_device_from_cdev(struct ccw_device *cdev)
{
struct dasd_devmap *devmap;
struct dasd_device *device;
unsigned long flags;
device = ERR_PTR(-ENODEV);
spin_lock(&dasd_devmap_lock);
devmap = cdev->dev.driver_data;
if (devmap && devmap->device) {
device = devmap->device;
dasd_get_device(device);
}
spin_unlock(&dasd_devmap_lock);
spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
device = dasd_device_from_cdev_locked(cdev);
spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
return device;
}
@ -730,16 +751,17 @@ static ssize_t
dasd_discipline_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct dasd_devmap *devmap;
char *dname;
struct dasd_device *device;
ssize_t len;
spin_lock(&dasd_devmap_lock);
dname = "none";
devmap = dev->driver_data;
if (devmap && devmap->device && devmap->device->discipline)
dname = devmap->device->discipline->name;
spin_unlock(&dasd_devmap_lock);
return snprintf(buf, PAGE_SIZE, "%s\n", dname);
device = dasd_device_from_cdev(to_ccwdev(dev));
if (!IS_ERR(device) && device->discipline) {
len = snprintf(buf, PAGE_SIZE, "%s\n",
device->discipline->name);
dasd_put_device(device);
} else
len = snprintf(buf, PAGE_SIZE, "none\n");
return len;
}
static DEVICE_ATTR(discipline, 0444, dasd_discipline_show, NULL);

1
drivers/s390/block/dasd_int.h
View File

@ -534,6 +534,7 @@ int dasd_add_sysfs_files(struct ccw_device *);
void dasd_remove_sysfs_files(struct ccw_device *);
struct dasd_device *dasd_device_from_cdev(struct ccw_device *);
struct dasd_device *dasd_device_from_cdev_locked(struct ccw_device *);
struct dasd_device *dasd_device_from_devindex(int);
int dasd_parse(void);