Merge branch 'Generic XDP improvements'

Kumar Kartikeya says:

====================

This small series makes some improvements to generic XDP mode and brings it
closer to native XDP. Patch 1 splits out generic XDP processing into reusable
parts, patch 2 adds pointer friendly wrappers for bitops (not have to cast back
and forth the address of local pointer to unsigned long *), patch 3 implements
generic cpumap support (details in commit) and patch 4 allows devmap bpf prog
execution before generic_xdp_tx is called.

Patch 5 just updates a couple of selftests to adapt to changes in behavior (in
that specifying devmap/cpumap prog fd in generic mode is now allowed).

Changelog:
----------
v5 -> v6
v5: https://lore.kernel.org/bpf/20210701002759.381983-1-memxor@gmail.com
 * Put rcpu->prog check before RCU-bh section to avoid do_softirq (Jesper)

v4 -> v5
v4: https://lore.kernel.org/bpf/20210628114746.129669-1-memxor@gmail.com
 * Add comments and examples for new bitops macros (Alexei)

v3 -> v4
v3: https://lore.kernel.org/bpf/20210622202835.1151230-1-memxor@gmail.com
 * Add detach now that attach of XDP program succeeds (Toke)
 * Clean up the test to use new ASSERT macros

v2 -> v3
v2: https://lore.kernel.org/bpf/20210622195527.1110497-1-memxor@gmail.com
 * list_for_each_entry -> list_for_each_entry_safe (due to deletion of skb)

v1 -> v2
v1: https://lore.kernel.org/bpf/20210620233200.855534-1-memxor@gmail.com


 * Move __ptr_{set,clear,test}_bit to bitops.h (Toke)
   Also changed argument order to match the bit op they wrap.
 * Remove map value size checking functions for cpumap/devmap (Toke)
 * Rework prog run for skb in cpu_map_kthread_run (Toke)
 * Set skb->dev to dst->dev after devmap prog has run
 * Don't set xdp rxq that will be overwritten in cpumap prog run
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>