[RFC PATCH 06/10] net: add SO_DEVMEM_DONTNEED setsockopt to release RX pages
Andy Lutomirski
luto at kernel.org
Sun Jul 16 23:57:07 UTC 2023
On 7/10/23 15:32, Mina Almasry wrote:
> Add an interface for the user to notify the kernel that it is done reading
> the NET_RX dmabuf pages returned as cmsg. The kernel will drop the
> reference on the NET_RX pages to make them available for re-use.
>
> Signed-off-by: Mina Almasry <almasrymina at google.com>
> ---
> + for (i = 0; i < num_tokens; i++) {
> + for (j = 0; j < tokens[i].token_count; j++) {
> + struct page *pg = xa_erase(&sk->sk_pagepool,
> + tokens[i].token_start + j);
> +
> + if (pg)
> + put_page(pg);
> + else
> + /* -EINTR here notifies the userspace
> + * that not all tokens passed to it have
> + * been freed.
> + */
> + ret = -EINTR;
Unless I'm missing something, this type of error reporting is
unrecoverable -- userspace doesn't know how many tokens have been freed.
I think you should either make it explicitly unrecoverable (somehow shut
down dmabuf handling entirely) or tell userspace how many tokens were
successfully freed.
--Andy
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