David Howells wrote:

Willem de Bruijn [off-list ref] wrote:

quoted

No need to modify __sys_sendmmsg explicitly, as it ends up calling
__sys_sendmsg?

Also, sendpage does this flags masking in the internal sock_FUNC
helpers rather than __sys_FUNC. Might be preferable.

I was wondering whether other flags, such as MSG_BATCH should be added to the
list.  Is it bad if userspace sets that in sendmsg()?  AF_KCM, at least, looks
at it.

That flag was added exactly for AF_KCM. A process that explicitly
sets it might experience bad behavior (increased latency), but
there are no legacy AF_KCM applications that precede the flag.