On Thu, Jul 23, 2020 at 12:30:25PM -0300, Marcelo Ricardo Leitner wrote:

On Thu, Jul 23, 2020 at 11:22:38AM +0200, Christoph Hellwig wrote:

quoted

On Wed, Jul 22, 2020 at 05:42:31PM -0300, Marcelo Ricardo Leitner wrote:

quoted

Cc'ing linux-sctp@vger.kernel.org.

What do you think of this version, which I think is a little cleaner?

It splits up the argument parsing from the actual handling, ok. Looks
good. Just one point:

quoted

+static int sctp_setsockopt_delayed_ack(struct sock *sk,
+				       struct sctp_sack_info *params,
+				       unsigned int optlen)
+{
+	if (optlen == sizeof(struct sctp_assoc_value)) {
+		struct sctp_sack_info p;
+
+		pr_warn_ratelimited(DEPRECATED
+				    "%s (pid %d) "
+				    "Use of struct sctp_assoc_value in delayed_ack socket option.\n"
+				    "Use struct sctp_sack_info instead\n",
+				    current->comm, task_pid_nr(current));
+
+		memcpy(&p, params, sizeof(struct sctp_assoc_value));
+		p.sack_freq = p.sack_delay ? 0 : 1;

Please add a comment saying that sctp_sack_info.sack_delay maps
exactly to sctp_assoc_value.assoc_value, so that's why we can do
memcpy and read assoc_value as sack_delay. I think it will help us not
trip on this again in the future.

Yeah.  Actually I think I'll go all the way and kill the not very
obvious or type safe memcpy as well.