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authorJan Höppner <hoeppner@linux.vnet.ibm.com>2016-10-12 13:51:04 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-10-28 11:09:04 +0300
commit9de67725c80cb8a7b34b1932e196d2ed61a08879 (patch)
tree3a29c6b57286e62cd550542abcddde4c8fde34bc /drivers/s390
parent0f57c97f241b4fc18251fb2b1c499e9f71e93c78 (diff)
downloadlinux-9de67725c80cb8a7b34b1932e196d2ed61a08879.tar.xz
s390/dasd: Fix locking issue when changing EER attribute
The reference to a device in question may get lost when the extended error reporting (EER) attribute is being enabled/disabled while the device is set offline at the same time. This is due to missing refcounting and incorrect locking. Fix this by the following: - In dasd_eer_store() get the device directly and handle the refcount accordingly. - Move the lock in dasd_eer_enable() up so we can ensure safe processing. - Check if the device is being set offline and return with -EBUSY if so. - While at it, change the return code from -EPERM to -EMEDIUMTYPE as suggested by a FIXME, since that is what we're actually checking. Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/block/dasd_devmap.c27
-rw-r--r--drivers/s390/block/dasd_eer.c29
2 files changed, 34 insertions, 22 deletions
diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 221d8c8e63d5..c1979ecce821 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -1167,26 +1167,25 @@ static ssize_t
dasd_eer_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
- struct dasd_devmap *devmap;
+ struct dasd_device *device;
unsigned int val;
- int rc;
+ int rc = 0;
- devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
- if (IS_ERR(devmap))
- return PTR_ERR(devmap);
- if (!devmap->device)
- return -ENODEV;
+ device = dasd_device_from_cdev(to_ccwdev(dev));
+ if (IS_ERR(device))
+ return PTR_ERR(device);
if (kstrtouint(buf, 0, &val) || val > 1)
return -EINVAL;
- if (val) {
- rc = dasd_eer_enable(devmap->device);
- if (rc)
- return rc;
- } else
- dasd_eer_disable(devmap->device);
- return count;
+ if (val)
+ rc = dasd_eer_enable(device);
+ else
+ dasd_eer_disable(device);
+
+ dasd_put_device(device);
+
+ return rc ? : count;
}
static DEVICE_ATTR(eer_enabled, 0644, dasd_eer_show, dasd_eer_store);
diff --git a/drivers/s390/block/dasd_eer.c b/drivers/s390/block/dasd_eer.c
index 21ef63cf0960..6c5d671304b4 100644
--- a/drivers/s390/block/dasd_eer.c
+++ b/drivers/s390/block/dasd_eer.c
@@ -454,20 +454,30 @@ static void dasd_eer_snss_cb(struct dasd_ccw_req *cqr, void *data)
*/
int dasd_eer_enable(struct dasd_device *device)
{
- struct dasd_ccw_req *cqr;
+ struct dasd_ccw_req *cqr = NULL;
unsigned long flags;
struct ccw1 *ccw;
+ int rc = 0;
+ spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
if (device->eer_cqr)
- return 0;
+ goto out;
+ else if (!device->discipline ||
+ strcmp(device->discipline->name, "ECKD"))
+ rc = -EMEDIUMTYPE;
+ else if (test_bit(DASD_FLAG_OFFLINE, &device->flags))
+ rc = -EBUSY;
- if (!device->discipline || strcmp(device->discipline->name, "ECKD"))
- return -EPERM; /* FIXME: -EMEDIUMTYPE ? */
+ if (rc)
+ goto out;
cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* SNSS */,
SNSS_DATA_SIZE, device);
- if (IS_ERR(cqr))
- return -ENOMEM;
+ if (IS_ERR(cqr)) {
+ rc = -ENOMEM;
+ cqr = NULL;
+ goto out;
+ }
cqr->startdev = device;
cqr->retries = 255;
@@ -485,15 +495,18 @@ int dasd_eer_enable(struct dasd_device *device)
cqr->status = DASD_CQR_FILLED;
cqr->callback = dasd_eer_snss_cb;
- spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
if (!device->eer_cqr) {
device->eer_cqr = cqr;
cqr = NULL;
}
+
+out:
spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
+
if (cqr)
dasd_kfree_request(cqr, device);
- return 0;
+
+ return rc;
}
/*