diff options
| -rw-r--r-- | drivers/s390/char/vmur.c | 218 | ||||
| -rw-r--r-- | drivers/s390/char/vmur.h | 1 |
2 files changed, 161 insertions, 58 deletions
diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c index 2d96c95..d70a6e6 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 2b3c564..fa95964 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 */ }; /* |