From: Eduard Zingerman <eddyz87@gmail.com>
To: Yureka Lilian <yuka@yuka.dev>,
Andrii Nakryiko <andrii@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>,
Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>
Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] bpf: fix reuse of DEVMAP
Date: Wed, 13 Aug 2025 14:59:50 -0700 [thread overview]
Message-ID: <77510736c4220e4f745fd152721e86689d8636d8.camel@gmail.com> (raw)
In-Reply-To: <20250813200912.3523279-2-yuka@yuka.dev>
On Wed, 2025-08-13 at 22:09 +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,
> but BPF_F_RDONLY_PROG being set on a map during creation is invalid.
>
> Thus, ignore the BPF_F_RDONLY_PROG flag on both sides when checking for
> compatibility with an existing DEVMAP.
>
> Ignoring it on both sides ensures that it continues to work on older
> kernels which don't set BPF_F_RDONLY_PROG on get_map_info.
>
> The same problem is handled in a third-party ebpf library:
> - https://github.com/cilium/ebpf/issues/925
> - https://github.com/cilium/ebpf/pull/930
>
> Fixes: 0cdbb4b09a06 ("devmap: Allow map lookups from eBPF")
> Signed-off-by: Yureka Lilian <yuka@yuka.dev>
> ---
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
next prev parent reply other threads:[~2025-08-13 21:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-13 20:09 [PATCH v2 0/2] " Yureka Lilian
2025-08-13 20:09 ` [PATCH v2 1/2] " Yureka Lilian
2025-08-13 21:59 ` Eduard Zingerman [this message]
2025-08-13 22:49 ` Andrii Nakryiko
2025-08-13 20:09 ` [PATCH v2 2/2] bpf: add test for DEVMAP reuse Yureka Lilian
2025-08-13 21:54 ` Eduard Zingerman
2025-08-13 22:01 ` [PATCH v2 0/2] bpf: fix reuse of DEVMAP Eduard Zingerman
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