From nobody Sat Oct 4 17:31:16 2025 Received: from mail.cyberchaos.dev (mail.cyberchaos.dev [195.39.247.168]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3431915855E; Thu, 14 Aug 2025 18:02:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.39.247.168 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755194531; cv=none; b=G0SN+QJnNlSx/NtbOhFvTyXoZT7dhrf5X2T4i4KEeoPG22NWoQvAvIyMytbM+HXk5Ou3b3+vB/KPNgV1+eGM+skvSQRy8MesfWSOtPXM6wbJF7Inh0IYEc0kbGS8d+PMJL7PEoxY4lE5cIHY5+LV+wQks0XW3cy635FnAmwf/tg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755194531; c=relaxed/simple; bh=gETrYTUSxPyYNdyon9BOH6C2hcZqinpne34HGLVzowc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lzUPACve7MYbE/V5iTUM5QwqwVQ3s5WyZZGWinE17a/oxIUMZiCNxCGRg3Efcbm+iyHHuvzLJlWRxQuq4kTzoeyMMDJSNlNHJv6QeblA2ZKr8eO9r+ymQPZkASb9aokCiMB9pvpTtVVFRcSQLjKNP8jut4mEeH2zrdRczbSDEUY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=yuka.dev; spf=pass smtp.mailfrom=yuka.dev; dkim=pass (1024-bit key) header.d=yuka.dev header.i=@yuka.dev header.b=lePV3CC3; arc=none smtp.client-ip=195.39.247.168 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=yuka.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=yuka.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=yuka.dev header.i=@yuka.dev header.b="lePV3CC3" From: Yureka Lilian DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yuka.dev; s=mail; t=1755194526; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sdxi0jU5vM3I1jrMekEXPFlRfKSHNBslgCtIr7Ic8W0=; b=lePV3CC3cAfRWS53LJwdV0+LzstjpROUjhvLrLfhzFil/Xf9C7ofDetp2CncB7mKo8rhz2 bzG9QV2MvcRAkrQjQ1fqJUBHMF/joPwOP+5QUVEsnj827gl7xZAWn20oC3xk0i93HrsK+5 3kq6xOGeCuzP/4rjMj3AVb6P3ihVkW8= To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa Cc: Yureka Lilian , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] libbpf: fix reuse of DEVMAP Date: Thu, 14 Aug 2025 20:01:12 +0200 Message-ID: <20250814180113.1245565-3-yuka@yuka.dev> In-Reply-To: <20250814180113.1245565-2-yuka@yuka.dev> References: <20250814180113.1245565-2-yuka@yuka.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 in the flags returned from get_map_info when checking for compatibility with an existing DEVMAP. 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 --- tools/lib/bpf/libbpf.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index d41ee26b9..affcbb231 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5088,6 +5088,17 @@ static bool map_is_reuse_compat(const struct bpf_map= *map, int map_fd) return false; } =20 + /* get_map_info on a DEVMAP will always return flags with + * BPF_F_RDONLY_PROG set, but it will never be set on a map + * being created. + * Thus, ignore the BPF_F_RDONLY_PROG flag in the flags + * returned from get_map_info when checking for compatibility + * with an existing DEVMAP. + */ + if (map->def.type =3D=3D BPF_MAP_TYPE_DEVMAP || map->def.type =3D=3D BPF_= MAP_TYPE_DEVMAP_HASH) { + map_info.map_flags &=3D ~BPF_F_RDONLY_PROG; + } + return (map_info.type =3D=3D map->def.type && map_info.key_size =3D=3D map->def.key_size && map_info.value_size =3D=3D map->def.value_size && --=20 2.50.1