From 9de67725c80cb8a7b34b1932e196d2ed61a08879 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Jan=20H=C3=B6ppner?= Date: Wed, 12 Oct 2016 12:51:04 +0200 Subject: [PATCH] s390/dasd: Fix locking issue when changing EER attribute MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Jan Höppner Signed-off-by: Martin Schwidefsky --- drivers/s390/block/dasd_devmap.c | 27 +++++++++++++-------------- drivers/s390/block/dasd_eer.c | 29 +++++++++++++++++++++-------- 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; } /* -- 2.39.5