Re: [PATCH 03/11] tcp_splice: Don't handle EPOLL_CTL_DEL as part of tcp_splice_epoll_ctl()

On Fri, Nov 03, 2023 at 05:20:53PM +0100, Stefano Brivio wrote:

On Thu, 12 Oct 2023 12:51:06 +1100 David Gibson wrote:

...

tcp_splice_epoll_ctl() removes both sockets from the epoll set if called when conn->flags & CLOSING. This will always happen immediately after setting that flag, since conn_flag_do() makes the call itself. That's also the _only_ time it can happen: we perform the EPOLL_CTL_DEL without clearing the conn->in_epoll flag, meaning that any further calls to tcp_splice_epoll_ctl() would attempt EPOLL_CTL_MOD, which would necessarily fail since the fds are no longer in the epoll.

The EPOLL_CTL_DEL path in tcp_splice_epoll_ctl() has essentially zero overlap with anything else the function does, so just move them to be open coded in conn_flag_do().

Caveat: this does require kernel 2.6.9 or later, in order to pass NULL as the event structure for epoll_ctl(). I _think_ we already require newer kernels than that for other features.

Yes, we do, we need at least 3.13 for unprivileged user namespaces.

Thanks, message updated accordingly. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson