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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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