USB: gadget: file_storage: put_device() in error recovery

This commit fixes some issues with File-backed Storage Gadget
error recovery when registering LUN's devices.

First of all, when device_register() fails the device still
needs to be put.  However, because lun_release() decreases
fsg->ref reference counter the counter must be incremented
beforehand.

Second of all, after any of the device_create_file()s fails,
device_unregister() is called which in turn (indirectly) calls
lun_release() which decrements fsg->ref.  So, again, the
reference counter must be incremented beforehand.

Lastly, if the first or the second device_create_file()
succeeds, the files are never removed.  To fix it,
device_remove_file() needs to be called.  This is done by
simply marking LUN as registered prior to creating files so
that fsg_unbind() can handle removing files.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Reported-by: Rahul Ruikar <rahul.ruikar@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 16 insertions, 13 deletions

diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index d4fdf65fb925..a6eacb59571b 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -3392,25 +3392,28 @@ static int __init fsg_bind(struct usb_gadget *gadget)
                 dev_set_name(&curlun->dev,"%s-lun%d",
                              dev_name(&gadget->dev), i);
 
-                if ((rc = device_register(&curlun->dev)) != 0) {
+                kref_get(&fsg->ref);
+                rc = device_register(&curlun->dev);
+                if (rc) {
                         INFO(fsg, "failed to register LUN%d: %d\n", i, rc);
-                        goto out;
-                }
-                if ((rc = device_create_file(&curlun->dev,
-                                        &dev_attr_ro)) != 0 ||
-                                (rc = device_create_file(&curlun->dev,
-                                        &dev_attr_nofua)) != 0 ||
-                                (rc = device_create_file(&curlun->dev,
-                                        &dev_attr_file)) != 0) {
-                        device_unregister(&curlun->dev);
+                        put_device(&curlun->dev);
                         goto out;
                 }
                 curlun->registered = 1;
-                kref_get(&fsg->ref);
+
+                rc = device_create_file(&curlun->dev, &dev_attr_ro);
+                if (rc)
+                        goto out;
+                rc = device_create_file(&curlun->dev, &dev_attr_nofua);
+                if (rc)
+                        goto out;
+                rc = device_create_file(&curlun->dev, &dev_attr_file);
+                if (rc)
+                        goto out;
 
                 if (mod_data.file[i] && *mod_data.file[i]) {
-                        if ((rc = fsg_lun_open(curlun,
-                                        mod_data.file[i])) != 0)
+                        rc = fsg_lun_open(curlun, mod_data.file[i]);
+                        if (rc)
                                 goto out;
                 } else if (!mod_data.removable) {
                         ERROR(fsg, "no file given for LUN%d\n", i);