Messages in this thread | | | Date | Thu, 16 Mar 2023 15:00:46 -0400 | From | Willem de Bruijn <> | Subject | Re: [RFC PATCH 03/28] tcp: Support MSG_SPLICE_PAGES |
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David Howells wrote: > Willem de Bruijn <willemdebruijn.kernel@gmail.com> wrote: > > > The commit message mentions MSG_SPLICE_PAGES as an internal flag. > > > > It can be passed from userspace. The code anticipates that and checks > > preconditions. > > Should I add a separate field in the in-kernel msghdr struct for such internal > flags? That would also avoid putting an internal flag in the same space as > the uapi flags.
That would work, if no cost to common paths that don't need it.
A not very pretty alternative would be to add an an extra arg to each sendmsg handler that is used only when called from sendpage.
There are a few other internal MSG_.. flags, such as MSG_SENDPAGE_NOPOLICY. Those are all limited to sendpage, and ignored in sendmsg, I think. Which would explain why it was clearly safe to add them.
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