From nobody Thu Dec 18 18:49:16 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6777AC41513 for ; Mon, 14 Aug 2023 19:00:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231761AbjHNS7i (ORCPT ); Mon, 14 Aug 2023 14:59:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41922 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231828AbjHNS7X (ORCPT ); Mon, 14 Aug 2023 14:59:23 -0400 Received: from mail-qt1-f170.google.com (mail-qt1-f170.google.com [209.85.160.170]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8519310F2; Mon, 14 Aug 2023 11:59:22 -0700 (PDT) Received: by mail-qt1-f170.google.com with SMTP id d75a77b69052e-40ff796e8ddso36052591cf.2; Mon, 14 Aug 2023 11:59:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692039561; x=1692644361; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=tFsZYglbIoheMRdnUX+qlZ0MFAe72xqHNVYG2PQUmMI=; b=kmlHjjL+NrrCbl48hiCNs3SFWVjWqyUuvQkwkx1W/MxM3BEZAKa9YbJ0iYtQPvLROd EGfrWtvrzW0pm/jHPdzz8gG+wvP1yIYkS4peLkZ59KzTivbrq64Fwy3FJU9v08aSshGv 2wLfQX9PLHB3k0nzqpc4Z0gfJIiDH4BaZ6bsCvwapwbjm7DIm/j2gpDJPg7pfXGc+mcK NQ60ygvhc30WCWPyACc1rXqf9V71GEbJHsPmvIZyWkcTQmaj+2MTzaI7BFXHAeVAitCO SJGua1QlD117IvMzBMK7P6lkSORoSdYxMCLNE1BMS8oWjPh95Zexwiw130Ek6RvsGB3T dWMA== X-Gm-Message-State: AOJu0YxCkalGLFLit1P3zgmdHHDazMPxPyXeDgzgFSemZ62FcK3YdIBJ MJXCxdf4D2fWi/QkBm++7s2aDRXUxvUBuBa9 X-Google-Smtp-Source: AGHT+IFrP3BKp7vJH8r6t9jh/zesUXJcFDd7e6j/KQDpSz31cru/oAx9m+dOyy1rkEiPQvfFCgdsHQ== X-Received: by 2002:ac8:5b91:0:b0:40f:bc9a:3262 with SMTP id a17-20020ac85b91000000b0040fbc9a3262mr13578948qta.21.1692039561291; Mon, 14 Aug 2023 11:59:21 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:93a1]) by smtp.gmail.com with ESMTPSA id m19-20020ac86893000000b00403cce833eesm3288487qtq.27.2023.08.14.11.59.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Aug 2023 11:59:20 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, tj@kernel.org, clm@meta.com, thinker.li@gmail.com, netdev@vger.kernel.org Subject: [PATCH bpf-next v3 1/2] bpf: Support default .validate() and .update() behavior for struct_ops links Date: Mon, 14 Aug 2023 13:59:07 -0500 Message-ID: <20230814185908.700553-2-void@manifault.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230814185908.700553-1-void@manifault.com> References: <20230814185908.700553-1-void@manifault.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Currently, if a struct_ops map is loaded with BPF_F_LINK, it must also define the .validate() and .update() callbacks in its corresponding struct bpf_struct_ops in the kernel. Enabling struct_ops link is useful in its own right to ensure that the map is unloaded if an application crashes. For example, with sched_ext, we want to automatically unload the host-wide scheduler if the application crashes. We would likely never support updating elements of a sched_ext struct_ops map, so we'd have to implement these callbacks showing that they _can't_ support element updates just to benefit from the basic lifetime management of struct_ops links. Let's enable struct_ops maps to work with BPF_F_LINK even if they haven't defined these callbacks, by assuming that a struct_ops map element cannot be updated by default. Acked-by: Kui-Feng Lee Signed-off-by: David Vernet --- kernel/bpf/bpf_struct_ops.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index eaff04eefb31..fdc3e8705a3c 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -509,9 +509,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_= map *map, void *key, } =20 if (st_map->map.map_flags & BPF_F_LINK) { - err =3D st_ops->validate(kdata); - if (err) - goto reset_unlock; + err =3D 0; + if (st_ops->validate) { + err =3D st_ops->validate(kdata); + if (err) + goto reset_unlock; + } set_memory_rox((long)st_map->image, 1); /* Let bpf_link handle registration & unregistration. * @@ -663,9 +666,6 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union b= pf_attr *attr) if (attr->value_size !=3D vt->size) return ERR_PTR(-EINVAL); =20 - if (attr->map_flags & BPF_F_LINK && (!st_ops->validate || !st_ops->update= )) - return ERR_PTR(-EOPNOTSUPP); - t =3D st_ops->type; =20 st_map_size =3D sizeof(*st_map) + @@ -823,6 +823,9 @@ static int bpf_struct_ops_map_link_update(struct bpf_li= nk *link, struct bpf_map if (!bpf_struct_ops_valid_to_reg(new_map)) return -EINVAL; =20 + if (!st_map->st_ops->update) + return -EOPNOTSUPP; + mutex_lock(&update_mutex); =20 old_map =3D rcu_dereference_protected(st_link->map, lockdep_is_held(&upda= te_mutex)); --=20 2.41.0