Daniel Borkmann wrote:
> On 11/7/20 8:37 PM, John Fastabend wrote:
> > If copy_page_to_iter() fails or even partially completes, but with fewer
> > bytes copied than expected we currently reset sg.start and return EFAULT.
> > This proves problematic if we already copied data into the user buffer
> > before we return an error. Because we leave the copied data in the user
> > buffer and fail to unwind the scatterlist so kernel side believes data
> > has been copied and user side believes data has _not_ been received.
[...]
> > + if (!copy) {
> > + return copied ? copied : -EFAULT;
> > }
>
> nit: no need for {}
>
> >
> > copied += copy;
> > @@ -56,6 +55,11 @@ int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
> > put_page(page);
> > }
> > } else {
> > + /* Lets not optimize peek case if copy_page_to_iter
> > + * didn't copy the entire length lets just break.
> > + */
> > + if (copy != sge->length)
> > + goto out;
>
> nit: return copied;
>
> Rest lgtm for this one.
Great, thanks for the review will fixup in v2.
