scsi: utilize new cdev_device_add helper function

This driver did not set kobj.parent so it likely suffered from
a potential use after free race if the user unregistered the
device while it was in use.

This was not so straightforward a conversion but I think this patch
cleans up its probe's error path significantly.

This patch adds device_initialize, which is required for
cdev_device_add. Then it switches to put_device instead of kfree as
recommended by device_initialize's documentation. This removes a lot
from the error path which was already in __remove.
A couple things needed to be re-ordered to be entirely correct, though.
ida_remove is also moved out of __remove and into unregister to
simplify things and follow the pattern other devices are using.

This also drop an extra unnecessary get_device/put_device in the code.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/scsi/osd/osd_uld.c b/drivers/scsi/osd/osd_uld.c
index e0ce5d2fd14d29656ab5409b9356217118ce0a98..4101c3178411f2c188401a62487740e93530ea96 100644 (file)
--- a/drivers/scsi/osd/osd_uld.c
+++ b/drivers/scsi/osd/osd_uld.c
@@ -400,9 +400,6 @@ static void __remove(struct device *dev)
 
        kfree(oud->odi.osdname);
 
-       if (oud->cdev.owner)
-               cdev_del(&oud->cdev);
-
        osd_dev_fini(&oud->od);
        scsi_device_put(scsi_device);
 
@@ -411,7 +408,6 @@ static void __remove(struct device *dev)
 
        if (oud->disk)
                put_disk(oud->disk);
-       ida_remove(&osd_minor_ida, oud->minor);
 
        kfree(oud);
 }
@@ -446,8 +442,20 @@ static int osd_probe(struct device *dev)
        if (NULL == oud)
                goto err_retract_minor;
 
+       /* class device member */
+       device_initialize(&oud->class_dev);
        dev_set_drvdata(dev, oud);
        oud->minor = minor;
+       oud->class_dev.devt = MKDEV(SCSI_OSD_MAJOR, oud->minor);
+       oud->class_dev.class = &osd_uld_class;
+       oud->class_dev.parent = dev;
+       oud->class_dev.release = __remove;
+
+       /* hold one more reference to the scsi_device that will get released
+        * in __release, in case a logout is happening while fs is mounted
+        */
+       scsi_device_get(scsi_device);
+       osd_dev_init(&oud->od, scsi_device);
 
        /* allocate a disk and set it up */
        /* FIXME: do we need this since sg has already done that */
@@ -461,59 +469,34 @@ static int osd_probe(struct device *dev)
        sprintf(disk->disk_name, "osd%d", oud->minor);
        oud->disk = disk;
 
-       /* hold one more reference to the scsi_device that will get released
-        * in __release, in case a logout is happening while fs is mounted
-        */
-       scsi_device_get(scsi_device);
-       osd_dev_init(&oud->od, scsi_device);
-
        /* Detect the OSD Version */
        error = __detect_osd(oud);
        if (error) {
                OSD_ERR("osd detection failed, non-compatible OSD device\n");
-               goto err_put_disk;
+               goto err_free_osd;
        }
 
        /* init the char-device for communication with user-mode */
        cdev_init(&oud->cdev, &osd_fops);
        oud->cdev.owner = THIS_MODULE;
-       error = cdev_add(&oud->cdev,
-                        MKDEV(SCSI_OSD_MAJOR, oud->minor), 1);
-       if (error) {
-               OSD_ERR("cdev_add failed\n");
-               goto err_put_disk;
-       }
 
-       /* class device member */
-       oud->class_dev.devt = oud->cdev.dev;
-       oud->class_dev.class = &osd_uld_class;
-       oud->class_dev.parent = dev;
-       oud->class_dev.release = __remove;
        error = dev_set_name(&oud->class_dev, "%s", disk->disk_name);
        if (error) {
                OSD_ERR("dev_set_name failed => %d\n", error);
-               goto err_put_cdev;
+               goto err_free_osd;
        }
 
-       error = device_register(&oud->class_dev);
+       error = cdev_device_add(&oud->cdev, &oud->class_dev);
        if (error) {
                OSD_ERR("device_register failed => %d\n", error);
-               goto err_put_cdev;
+               goto err_free_osd;
        }
 
-       get_device(&oud->class_dev);
-
        OSD_INFO("osd_probe %s\n", disk->disk_name);
        return 0;
 
-err_put_cdev:
-       cdev_del(&oud->cdev);
-err_put_disk:
-       scsi_device_put(scsi_device);
-       put_disk(disk);
 err_free_osd:
-       dev_set_drvdata(dev, NULL);
-       kfree(oud);
+       put_device(&oud->class_dev);
 err_retract_minor:
        ida_remove(&osd_minor_ida, minor);
        return error;
@@ -530,9 +513,10 @@ static int osd_remove(struct device *dev)
                        scsi_device);
        }
 
-       device_unregister(&oud->class_dev);
-
+       cdev_device_del(&oud->cdev, &oud->class_dev);
+       ida_remove(&osd_minor_ida, oud->minor);
        put_device(&oud->class_dev);
+
        return 0;
 }