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Wed, 05 Feb 2025 09:00:33 -0800 (PST) Date: Wed, 5 Feb 2025 09:00:31 -0800 From: Yan Zhai To: Alexei Starovoitov Cc: Hou Tao , bpf , kernel-team Subject: Re: handling EINTR from bpf_map_lookup_batch Message-ID: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Feb 05, 2025 at 10:27:25AM -0600, Yan Zhai wrote: > On Wed, Feb 5, 2025 at 3:56 AM Alexei Starovoitov > wrote: > > > > Let's not invent new magic return values. > > > > But stepping back... why do we have this EINTR case at all? > > Can we always goto next_key for all map types? > > The command returns and a set of (key, value) pairs. > > It's always better to skip then get stuck in EINTR, > > since EINTR implies that the user space should retry and it > > might be successful next time. > > While here it's not the case. > > I don't see any selftests for EINTR, so I suspect it was added > > as escape path in case retry count exceeds 3 and author assumed > > that it should never happen in practice, so EINTR was expected > > to be 'never happens'. Clearly that's not the case. > > It makes more sense to me if we just goto the next key for all types. > At least for current users of generic batch lookup, arrays and > lpm_trie, I didn't notice in any case retry would help. > I opened a patch here: https://lore.kernel.org/bpf/Z6OYbS4WqQnmzi2z@debian.debian/ Yan