[PATCH 0/2] Allow bpf_user_ringbuf_drain() callbacks to return 1

[David Vernet <void@manifault.com>]

The bpf_user_ringbuf_drain() helper function allows a BPF program to
specify a callback that is invoked when draining entries from a
BPF_MAP_TYPE_USER_RINGBUF ring buffer map. The API is meant to allow the
callback to return 0 if it wants to continue draining samples, and 1 if
it's done draining. Unfortunately, bpf_user_ringbuf_drain() landed shortly
after commit 1bfe26fb0827 ("bpf: Add verifier support for custom
callback return range"), which changed the default behavior of callbacks
to only support returning 0, and the corresponding necessary change to
bpf_user_ringbuf_drain() callbacks was missed.

This patch set fixes this oversight, and updates the user_ringbuf
selftests to return 1 in a callback to catch future instances of
regression.

This patch set should be merged to the bpf tree.

David Vernet (2):
  bpf: Allow bpf_user_ringbuf_drain() callbacks to return 1
  selftests/bpf: Make bpf_user_ringbuf_drain() selftest callback return
    1

 kernel/bpf/verifier.c                                    | 1 +
 tools/testing/selftests/bpf/progs/user_ringbuf_success.c | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

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2.38.0