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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 commit1bfe26fb08("bpf: Add verifier support for custom callback return range"), which changed the default behavior of callbacks to only support returning 0. This patch corrects that oversight by allowing bpf_user_ringbuf_drain() callbacks to return 0 or 1. A follow-on patch will update the user_ringbuf selftests to also return 1 from a bpf_user_ringbuf_drain() callback to prevent this from regressing in the future. Fixes:2057156738("bpf: Add bpf_user_ringbuf_drain() helper") Signed-off-by: David Vernet <void@manifault.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20221012232015.1510043-2-void@manifault.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.