On Sun, 21 Feb 2021 21:09:54 +0100
Björn Töpel [off-list ref] wrote:

From: Björn Töpel <redacted>

The XDP_REDIRECT implementations for maps and non-maps are fairly
similar, but obviously need to take different code paths depending on
if the target is using a map or not. Today, the redirect targets for
XDP either uses a map, or is based on ifindex.

Here, an explicit redirect type is added to bpf_redirect_info, instead
of the actual map. Redirect type, map item/ifindex, and the map_id (if
any) is passed to xdp_do_redirect().

In addition to making the code easier to follow, using an explicit
type in bpf_redirect_info has a slight positive performance impact by
avoiding a pointer indirection for the map type lookup, and instead
use the cacheline for bpf_redirect_info.

Since the actual map is not passed via bpf_redirect_info anymore, the
map lookup is only done in the BPF helper. This means that the
bpf_clear_redirect_map() function can be removed. The actual map item
is RCU protected.

The bpf_redirect_info flags member is not used by XDP, and not
read/written any more. The map member is only written to when
required/used, and not unconditionally.

v1->v2 : Removed warning when CONFIG_BPF_SYSCALL was not set. (lkp)
       : Cleaned up case-clause in xdp_do_generic_redirect_map(). (Toke)
rfc->v1: Use map_id, and remove bpf_clear_redirect_map(). (Toke)

Acked-by: Toke Høiland-Jørgensen <redacted>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Björn Töpel <redacted>
---
 include/linux/bpf.h        |   1 +
 include/linux/filter.h     |  11 ++-
 include/trace/events/xdp.h |  66 +++++++++------
 kernel/bpf/cpumap.c        |   1 -
 kernel/bpf/devmap.c        |   1 -
 net/core/filter.c          | 165 ++++++++++++++++---------------------
 net/xdp/xskmap.c           |   1 -
 7 files changed, 122 insertions(+), 124 deletions(-)

I like it! :-)

Acked-by: Jesper Dangaard Brouer <redacted>

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer