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Subject[PATCHv2 1/7] USB: gadget: file_storage: put_device() in error recovery
Date
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>
---
drivers/usb/gadget/file_storage.c | 29 ++++++++++++++++-------------
1 files changed, 16 insertions(+), 13 deletions(-)
> On Tue, 26 Oct 2010, Michal Nazarewicz wrote:
>> + if ((rc = device_create_file(&curlun->dev, &dev_attr_ro)) ||
>> + (rc = device_create_file(&curlun->dev, &dev_attr_nofua)) ||
>> + (rc = device_create_file(&curlun->dev, &dev_attr_file)))
>> + goto out;

On Tue, 26 Oct 2010 16:09:27 +0200, Alan Stern <stern@rowland.harvard.edu> wrote:
> As long as you're changing these anyway, you may as well use the style
> most developers seem to prefer:
>
> rc = device_create_file(&curlun->dev, &dev_attr_ro);
> if (rc)
> goto out;

As requested, this commit changes exacly that.

diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index d4fdf65..a6eacb5 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);
--
1.7.1


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