• Jerry Zhang's avatar
    usb: gadget: f_fs: Only return delayed status when len is 0 · 4d644abf
    Jerry Zhang authored
    Commit 1b9ba000 ("Allow function drivers to pause control
    transfers") states that USB_GADGET_DELAYED_STATUS is only
    supported if data phase is 0 bytes.
    
    It seems that when the length is not 0 bytes, there is no
    need to explicitly delay the data stage since the transfer
    is not completed until the user responds. However, when the
    length is 0, there is no data stage and the transfer is
    finished once setup() returns, hence there is a need to
    explicitly delay completion.
    
    This manifests as the following bugs:
    
    Prior to 946ef68a ('Let setup() return
    USB_GADGET_DELAYED_STATUS'), when setup is 0 bytes, ffs
    would require user to queue a 0 byte request in order to
    clear setup state. However, that 0 byte request was actually
    not needed and would hang and cause errors in other setup
    requests.
    
    After the above commit, 0 byte setups work since the gadget
    now accepts empty queues to ep0 to clear the delay, but all
    other setups hang.
    
    Fixes: 946ef68a ("Let setup() return USB_GADGET_DELAYED_STATUS")
    Signed-off-by: default avatarJerry Zhang <zhangjerry@google.com>
    Cc: stable <stable@vger.kernel.org>
    Acked-by: default avatarFelipe Balbi <felipe.balbi@linux.intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    4d644abf
f_fs.c 87.7 KB