[PATCH v4 bpf 0/3] AF_XDP Socket Creation Fixes

[Ciara Loftus <ciara.loftus@intel.com>]

This series fixes some issues around socket creation for AF_XDP.

Patch 1 fixes a potential NULL pointer dereference in
xsk_socket__create_shared.

Patch 2 ensures that the umem passed to xsk_socket__create(_shared)
remains unchanged in event of failure.

Patch 3 makes it possible for xsk_socket__create(_shared) to
succeed even if the rx and tx XDP rings have already been set up by
introducing a new fields to struct xsk_umem which represent the ring
setup status for the xsk which shares the fd with the umem.

v3->v4:
* Reduced nesting in xsk_put_ctx as suggested by Alexei.
* Use bools instead of a u8 and flags to represent the
  ring setup status as suggested by Björn.

v2->v3:
* Instead of ignoring the return values of the setsockopt calls, introduce
  a new flag to determine whether or not to call them based on the ring
  setup status as suggested by Alexei.

v1->v2:
* Simplified restoring the _save pointers as suggested by Magnus.
* Fixed the condition which determines whether to unmap umem rings
 when socket create fails.

This series applies on commit 861de02e5f3f2a104eecc5af1d248cb7bf8c5f75

Ciara Loftus (3):
  libbpf: ensure umem pointer is non-NULL before dereferencing
  libbpf: restore umem state after socket create failure
  libbpf: only create rx and tx XDP rings when necessary

 tools/lib/bpf/xsk.c | 57 +++++++++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 20 deletions(-)

-- 
2.17.1