On Tue, 26 Oct 2010, Michal Nazarewicz wrote:
> From: Michal Nazarewicz <mina86@xxxxxxxxxx>
>
> 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.
Correct.
> 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.
Correct.
> 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.
Correct.
> Signed-off-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
> Reported-by: Rahul Ruikar <rahul.ruikar@xxxxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/usb/gadget/file_storage.c | 20 +++++++++-----------
> 1 files changed, 9 insertions(+), 11 deletions(-)
>
> Rahul sent an invalid fix for the missing put_device() problem some time
> ago. This is, I believe, a correct one. It also fixes the problem with
> device files not being removed (as described in commit message); not sure
> if the latter is a big issue though.
>
> Hope I'm not late for 37?
No doubt it is too late to get into the merge window. But it's not
too late for bug fixes to get into 2.6.37 -- there are still eight or
nine -rc's to go. :-)
> diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
> index d4fdf65..e0504a1 100644
> --- a/drivers/usb/gadget/file_storage.c
> +++ b/drivers/usb/gadget/file_storage.c
> @@ -3392,21 +3392,19 @@ 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);
> +
> + 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;
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;
...
After all, you did the same thing in the device_register() call above.
Apart from this small matter, ACK.
Alan Stern
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