linux-kernel - Re: [PATCH] bpf: fix reuse of DEVMAP

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Message-ID: <a94bafca6b9a03be3d09b76341c89ddef6ce9bbb.camel@gmail.com>
Date: Mon, 11 Aug 2025 10:29:41 -0700
From: Eduard Zingerman <eddyz87@...il.com>
To: Yureka Lilian <yuka@...a.dev>, Andrii Nakryiko <andrii@...nel.org>, 
 Alexei Starovoitov	 <ast@...nel.org>, Daniel Borkmann
 <daniel@...earbox.net>, Martin KaFai Lau	 <martin.lau@...ux.dev>, Song Liu
 <song@...nel.org>, Yonghong Song	 <yonghong.song@...ux.dev>, John Fastabend
 <john.fastabend@...il.com>, KP Singh	 <kpsingh@...nel.org>, Stanislav
 Fomichev <sdf@...ichev.me>, Hao Luo	 <haoluo@...gle.com>, Jiri Olsa
 <jolsa@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bpf: fix reuse of DEVMAP

On Mon, 2025-08-11 at 11:39 +0200, Yureka Lilian wrote:
> Previously, re-using pinned DEVMAP maps would always fail, because
> get_map_info on a DEVMAP always returns flags with BPF_F_RDONLY_PROG set,
> it BPF_F_RDONLY_PROG being set on a map being created is invalid.
> 
> Thus, match the BPF_F_RDONLY_PROG flag being set on the new map when
> checking for compatibility with an existing DEVMAP
> 
> The same problem is handled in third-party ebpf library:
> - https://github.com/cilium/ebpf/issues/925
> - https://github.com/cilium/ebpf/pull/930
> 
> Signed-off-by: Yureka Lilian <yuka@...a.dev>
> ---

The change makes sense to me, could you please add a selftest?

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