mainline inclusion
from mainline-5.13-rc1
commit 5c507329
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5c507329000e282dce91e6c98ee6ffa61a8a5e49

-------------------------------------------------

In 'bpf_ringbuf_reserve()' we require the flag to '0' at the moment.

For 'bpf_ringbuf_{discard,submit,output}' a flag of '0' might send a
notification to the process if needed.
Signed-off-by: NPedro Tammela <pctammela@mojatatu.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210412192434.944343-1-pctammela@mojatatu.com
(cherry picked from commit 5c507329)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>