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    SubjectRe: [PATCH -mm 4/10][RFC] aio: convert aio_complete to file_endio_t
    Date
    On Monday 15 January 2007 5:54 pm, Nate Diller wrote:
    > --- a/drivers/usb/gadget/inode.c 2007-01-12 14:42:29.000000000 -0800
    > +++ b/drivers/usb/gadget/inode.c 2007-01-12 14:25:34.000000000 -0800
    > @@ -559,35 +559,32 @@ static int ep_aio_cancel(struct kiocb *i
    > return value;
    > }
    >
    > -static ssize_t ep_aio_read_retry(struct kiocb *iocb)
    > +static int ep_aio_read_retry(struct kiocb *iocb)
    > {
    > struct kiocb_priv *priv = iocb->private;
    > - ssize_t len, total;
    > - int i;
    > + ssize_t total;
    > + int i, err = 0;
    >
    > /* we "retry" to get the right mm context for this: */
    >
    > /* copy stuff into user buffers */
    > total = priv->actual;
    > - len = 0;
    > for (i=0; i < priv->nr_segs; i++) {
    > ssize_t this = min((ssize_t)(priv->iv[i].iov_len), total);
    >
    > if (copy_to_user(priv->iv[i].iov_base, priv->buf, this)) {
    > - if (len == 0)
    > - len = -EFAULT;
    > + err = -EFAULT;

    Discarding the capability to report partial success, e.g. that the first N
    bytes were properly transferred? I don't see any virtue in that change.
    Quite the opposite in fact.

    I think you're also expecting that if N bytes were requested, that's always
    how many will be received. That's not true for packetized I/O such as USB
    isochronous transfers ... where it's quite legit (and in some cases routine)
    for the other end to send packets that are shorter than the maximum allowed.
    Sending a zero length packet is not the same as sending no packet at all,
    for another example.
    -
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