On Mon, Nov 26, 2018 at 1:04 PM Paolo Abeni <pab...@redhat.com> wrote: > > On Mon, 2018-11-26 at 12:59 -0500, Willem de Bruijn wrote: > > The callers of this function do flush the queue of the other skbs on > > error, but only after the call to sock_zerocopy_put_abort. > > > > sock_zerocopy_put_abort depends on total rollback to revert the > > sk_zckey increment and suppress the completion notification (which > > must not happen on return with error). > > > > I don't immediately have a fix. Need to think about this some more.. > > [still out of sheer ignorance] How about tacking a refcnt for the whole > ip_append_data() scope, like in the tcp case? that will add an atomic > op per loop (likely, hitting the cache) but will remove some code hunk > in sock_zerocopy_put_abort() and sock_zerocopy_alloc().
The atomic op pair is indeed what I was trying to avoid. But I also need to solve the problem that the final decrement will happen from the freeing of the other skbs in __ip_flush_pending_frames, and will not suppress the notification. Freeing the entire queue inside __ip_append_data, effectively making it a true noop on error is one approach. But that is invasive, also to non zerocopy codepaths, so I would rather avoid that. Perhaps I need to handle the abort logic in udp_sendmsg directly, after both __ip_append_data and __ip_flush_pending_frames.
