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-rw-r--r--drivers/s390/char/vmur.c218
-rw-r--r--drivers/s390/char/vmur.h1
2 files changed, 161 insertions, 58 deletions
diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c
index 2d96c958df64..d70a6e65bf14 100644
--- a/drivers/s390/char/vmur.c
+++ b/drivers/s390/char/vmur.c
@@ -69,8 +69,26 @@ static struct ccw_driver ur_driver = {
.set_offline = ur_set_offline,
};
+static DEFINE_MUTEX(vmur_mutex);
+
/*
* Allocation, freeing, getting and putting of urdev structures
+ *
+ * Each ur device (urd) contains a reference to its corresponding ccw device
+ * (cdev) using the urd->cdev pointer. Each ccw device has a reference to the
+ * ur device using the cdev->dev.driver_data pointer.
+ *
+ * urd references:
+ * - ur_probe gets a urd reference, ur_remove drops the reference
+ * (cdev->dev.driver_data)
+ * - ur_open gets a urd reference, ur_relase drops the reference
+ * (urf->urd)
+ *
+ * cdev references:
+ * - urdev_alloc get a cdev reference (urd->cdev)
+ * - urdev_free drops the cdev reference (urd->cdev)
+ *
+ * Setting and clearing of cdev->dev.driver_data is protected by the ccwdev lock
*/
static struct urdev *urdev_alloc(struct ccw_device *cdev)
{
@@ -79,42 +97,61 @@ static struct urdev *urdev_alloc(struct ccw_device *cdev)
urd = kzalloc(sizeof(struct urdev), GFP_KERNEL);
if (!urd)
return NULL;
- urd->cdev = cdev;
urd->reclen = cdev->id.driver_info;
ccw_device_get_id(cdev, &urd->dev_id);
mutex_init(&urd->io_mutex);
mutex_init(&urd->open_mutex);
+ atomic_set(&urd->ref_count, 1);
+ urd->cdev = cdev;
+ get_device(&cdev->dev);
return urd;
}
static void urdev_free(struct urdev *urd)
{
+ TRACE("urdev_free: %p\n", urd);
+ if (urd->cdev)
+ put_device(&urd->cdev->dev);
kfree(urd);
}
-/*
- * This is how the character device driver gets a reference to a
- * ur device. When this call returns successfully, a reference has
- * been taken (by get_device) on the underlying kobject. The recipient
- * of this urdev pointer must eventually drop it with urdev_put(urd)
- * which does the corresponding put_device().
- */
+static void urdev_get(struct urdev *urd)
+{
+ atomic_inc(&urd->ref_count);
+}
+
+static struct urdev *urdev_get_from_cdev(struct ccw_device *cdev)
+{
+ struct urdev *urd;
+ unsigned long flags;
+
+ spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+ urd = cdev->dev.driver_data;
+ if (urd)
+ urdev_get(urd);
+ spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+ return urd;
+}
+
static struct urdev *urdev_get_from_devno(u16 devno)
{
char bus_id[16];
struct ccw_device *cdev;
+ struct urdev *urd;
sprintf(bus_id, "0.0.%04x", devno);
cdev = get_ccwdev_by_busid(&ur_driver, bus_id);
if (!cdev)
return NULL;
-
- return cdev->dev.driver_data;
+ urd = urdev_get_from_cdev(cdev);
+ put_device(&cdev->dev);
+ return urd;
}
static void urdev_put(struct urdev *urd)
{
- put_device(&urd->cdev->dev);
+ if (atomic_dec_and_test(&urd->ref_count))
+ urdev_free(urd);
}
/*
@@ -246,6 +283,7 @@ static void ur_int_handler(struct ccw_device *cdev, unsigned long intparm,
return;
}
urd = cdev->dev.driver_data;
+ BUG_ON(!urd);
/* On special conditions irb is an error pointer */
if (IS_ERR(irb))
urd->io_request_rc = PTR_ERR(irb);
@@ -263,9 +301,15 @@ static void ur_int_handler(struct ccw_device *cdev, unsigned long intparm,
static ssize_t ur_attr_reclen_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- struct urdev *urd = dev->driver_data;
+ struct urdev *urd;
+ int rc;
- return sprintf(buf, "%zu\n", urd->reclen);
+ urd = urdev_get_from_cdev(to_ccwdev(dev));
+ if (!urd)
+ return -ENODEV;
+ rc = sprintf(buf, "%zu\n", urd->reclen);
+ urdev_put(urd);
+ return rc;
}
static DEVICE_ATTR(reclen, 0444, ur_attr_reclen_show, NULL);
@@ -726,64 +770,63 @@ static struct file_operations ur_fops = {
/*
* ccw_device infrastructure:
- * ur_probe gets its own ref to the device (i.e. get_device),
- * creates the struct urdev, the device attributes, sets up
- * the interrupt handler and validates the virtual unit record device.
- * ur_remove removes the device attributes, frees the struct urdev
- * and drops (put_device) the ref to the device we got in ur_probe.
+ * ur_probe creates the struct urdev (with refcount = 1), the device
+ * attributes, sets up the interrupt handler and validates the virtual
+ * unit record device.
+ * ur_remove removes the device attributes and drops the reference to
+ * struct urdev.
+ *
+ * ur_probe, ur_remove, ur_set_online and ur_set_offline are serialized
+ * by the vmur_mutex lock.
+ *
+ * urd->char_device is used as indication that the online function has
+ * been completed successfully.
*/
static int ur_probe(struct ccw_device *cdev)
{
struct urdev *urd;
int rc;
- TRACE("ur_probe: cdev=%p state=%d\n", cdev, *(int *) cdev->private);
-
- if (!get_device(&cdev->dev))
- return -ENODEV;
+ TRACE("ur_probe: cdev=%p\n", cdev);
+ mutex_lock(&vmur_mutex);
urd = urdev_alloc(cdev);
if (!urd) {
rc = -ENOMEM;
- goto fail;
+ goto fail_unlock;
}
+
rc = ur_create_attributes(&cdev->dev);
if (rc) {
rc = -ENOMEM;
- goto fail;
+ goto fail_urdev_put;
}
- cdev->dev.driver_data = urd;
cdev->handler = ur_int_handler;
/* validate virtual unit record device */
urd->class = get_urd_class(urd);
if (urd->class < 0) {
rc = urd->class;
- goto fail;
+ goto fail_remove_attr;
}
if ((urd->class != DEV_CLASS_UR_I) && (urd->class != DEV_CLASS_UR_O)) {
rc = -ENOTSUPP;
- goto fail;
+ goto fail_remove_attr;
}
+ spin_lock_irq(get_ccwdev_lock(cdev));
+ cdev->dev.driver_data = urd;
+ spin_unlock_irq(get_ccwdev_lock(cdev));
+ mutex_unlock(&vmur_mutex);
return 0;
-fail:
- urdev_free(urd);
- put_device(&cdev->dev);
- return rc;
-}
-
-static void ur_remove(struct ccw_device *cdev)
-{
- struct urdev *urd = cdev->dev.driver_data;
-
- TRACE("ur_remove\n");
- if (cdev->online)
- ur_set_offline(cdev);
+fail_remove_attr:
ur_remove_attributes(&cdev->dev);
- urdev_free(urd);
- put_device(&cdev->dev);
+fail_urdev_put:
+ urdev_put(urd);
+fail_unlock:
+ mutex_unlock(&vmur_mutex);
+ return rc;
}
static int ur_set_online(struct ccw_device *cdev)
@@ -792,20 +835,29 @@ static int ur_set_online(struct ccw_device *cdev)
int minor, major, rc;
char node_id[16];
- TRACE("ur_set_online: cdev=%p state=%d\n", cdev,
- *(int *) cdev->private);
+ TRACE("ur_set_online: cdev=%p\n", cdev);
- if (!try_module_get(ur_driver.owner))
- return -EINVAL;
+ mutex_lock(&vmur_mutex);
+ urd = urdev_get_from_cdev(cdev);
+ if (!urd) {
+ /* ur_remove already deleted our urd */
+ rc = -ENODEV;
+ goto fail_unlock;
+ }
+
+ if (urd->char_device) {
+ /* Another ur_set_online was faster */
+ rc = -EBUSY;
+ goto fail_urdev_put;
+ }
- urd = (struct urdev *) cdev->dev.driver_data;
minor = urd->dev_id.devno;
major = MAJOR(ur_first_dev_maj_min);
urd->char_device = cdev_alloc();
if (!urd->char_device) {
rc = -ENOMEM;
- goto fail_module_put;
+ goto fail_urdev_put;
}
cdev_init(urd->char_device, &ur_fops);
@@ -834,29 +886,79 @@ static int ur_set_online(struct ccw_device *cdev)
TRACE("ur_set_online: device_create rc=%d\n", rc);
goto fail_free_cdev;
}
-
+ urdev_put(urd);
+ mutex_unlock(&vmur_mutex);
return 0;
fail_free_cdev:
cdev_del(urd->char_device);
-fail_module_put:
- module_put(ur_driver.owner);
-
+ urd->char_device = NULL;
+fail_urdev_put:
+ urdev_put(urd);
+fail_unlock:
+ mutex_unlock(&vmur_mutex);
return rc;
}
-static int ur_set_offline(struct ccw_device *cdev)
+static int ur_set_offline_force(struct ccw_device *cdev, int force)
{
struct urdev *urd;
+ int rc;
- TRACE("ur_set_offline: cdev=%p cdev->private=%p state=%d\n",
- cdev, cdev->private, *(int *) cdev->private);
- urd = (struct urdev *) cdev->dev.driver_data;
+ TRACE("ur_set_offline: cdev=%p\n", cdev);
+ urd = urdev_get_from_cdev(cdev);
+ if (!urd)
+ /* ur_remove already deleted our urd */
+ return -ENODEV;
+ if (!urd->char_device) {
+ /* Another ur_set_offline was faster */
+ rc = -EBUSY;
+ goto fail_urdev_put;
+ }
+ if (!force && (atomic_read(&urd->ref_count) > 2)) {
+ /* There is still a user of urd (e.g. ur_open) */
+ TRACE("ur_set_offline: BUSY\n");
+ rc = -EBUSY;
+ goto fail_urdev_put;
+ }
device_destroy(vmur_class, urd->char_device->dev);
cdev_del(urd->char_device);
- module_put(ur_driver.owner);
+ urd->char_device = NULL;
+ rc = 0;
- return 0;
+fail_urdev_put:
+ urdev_put(urd);
+ return rc;
+}
+
+static int ur_set_offline(struct ccw_device *cdev)
+{
+ int rc;
+
+ mutex_lock(&vmur_mutex);
+ rc = ur_set_offline_force(cdev, 0);
+ mutex_unlock(&vmur_mutex);
+ return rc;
+}
+
+static void ur_remove(struct ccw_device *cdev)
+{
+ unsigned long flags;
+
+ TRACE("ur_remove\n");
+
+ mutex_lock(&vmur_mutex);
+
+ if (cdev->online)
+ ur_set_offline_force(cdev, 1);
+ ur_remove_attributes(&cdev->dev);
+
+ spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+ urdev_put(cdev->dev.driver_data);
+ cdev->dev.driver_data = NULL;
+ spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+
+ mutex_unlock(&vmur_mutex);
}
/*
diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h
index 2b3c564e0472..fa959644735a 100644
--- a/drivers/s390/char/vmur.h
+++ b/drivers/s390/char/vmur.h
@@ -70,6 +70,7 @@ struct urdev {
size_t reclen; /* Record length for *write* CCWs */
int class; /* VM device class */
int io_request_rc; /* return code from I/O request */
+ atomic_t ref_count; /* reference counter */
};
/*
generated by cgit v1.2.3 (git 2.0.4) at 2024-07-07 15:07:19 +0000