On Mon, 2023-06-26 at 14:22 -0700, Jakub Kicinski wrote: > On Mon, 26 Jun 2023 22:14:41 +0100 David Howells wrote: > > Do you know if ->sendmsg() might alter the msghdr struct it is passed as an > > argument? Certainly it can alter msg_iter, but can it also modify, > > say, msg_flags? > > I'm not aware of a precedent either way. > Eric or Paolo would know better than me, tho. udp_sendmsg() can set the MSG_TRUNC bit in msg->msg_flags, so I guess that kind of actions are sort of allowed. Still, AFAICS, the kernel based msghdr is not copied back to the user-space, so such change should be almost a no-op in practice. @David: which would be the end goal for such action? Cheers, Paolo
