Commit a00bfd71 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 47addc84

drivers/s390/block/dasd.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

drivers/s390/block/dasd_devmap.c

+48 −26
Original line number Diff line number Diff line
@@ -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);
@@ -615,21 +625,32 @@ dasd_put_device_wake(struct dasd_device *device) 


/*

 * 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(struct ccw_device *cdev)

dasd_device_from_cdev_locked(struct ccw_device *cdev)

{

	struct dasd_devmap *devmap;

	struct dasd_device *device;

	struct dasd_device *device = cdev->dev.driver_data;



	device = ERR_PTR(-ENODEV);

	spin_lock(&dasd_devmap_lock);

	devmap = cdev->dev.driver_data;

	if (devmap && devmap->device) {

		device = devmap->device;

	if (!device)

		return ERR_PTR(-ENODEV);

	dasd_get_device(device);

	return device;

}

	spin_unlock(&dasd_devmap_lock);



/*

 * Return dasd_device structure associated with cdev.

 */

struct dasd_device *

dasd_device_from_cdev(struct ccw_device *cdev)

{

	struct dasd_device *device;

	unsigned long flags;



	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);

drivers/s390/block/dasd_int.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

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