From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta1.migadu.com (out-177.mta1.migadu.com [95.215.58.177]) (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 760A6255E34 for ; Fri, 18 Apr 2025 22:47:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745016456; cv=none; b=hPJejFkuXn3WKcby3KnhYj3rxhitU6gH2rzDusPTz0gAV4gpBKaGe2htEx//wToI4mgPF+i4mBJt35eJdUZ2JU+O+qKzs6ILK/wZU0FrHVKCivAX3kFihLFS96cT6bYrv3fKlr2OoIQLuodg7t4H/pCAgNyRIKLe/MDSeQbpFc4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745016456; c=relaxed/simple; bh=Ya1zEAYNutolwv6KH1vqLiZ54drfZW43K2kgHG1e6dY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=elzkXZCKQHp0KjeRgmyR0xMNp8kUJIdR3BbXvJjX/ldUFXVszuY6c6hoXVCR+muuIHUYPNv1iRUBtSdicxNw3MfeJTuPtYBk3NlO76Z8Zc0WG5/GH8w23VoltlpnsHKqrnyYnMbUgBd26VbtKDTzF8GjZ6Yto8hwlKxGoatP1YQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=xtKtOTMn; arc=none smtp.client-ip=95.215.58.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="xtKtOTMn" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1745016452; 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=F0Jov62g6P3kuxMg3ohcNB00iUIpotsSk9z8qoAzQOE=; b=xtKtOTMnEtxdfp0clvr/p3wdzobNUVoQJCnBVa5mzBkNOMTfATSzbzbcHo/TYnUkfXxOmI qjL8q0hD4FMJDbZoybhXR0beVT/hZNcUSmxdbOuhhrK90QiGJxMzUC3BCm+sMNgF4DASin JCe2yFPjlWUseiFqn/pOIWM0d6O3N3w= From: Martin KaFai Lau To: bpf@vger.kernel.org Cc: 'Alexei Starovoitov ' , 'Andrii Nakryiko ' , 'Daniel Borkmann ' , netdev@vger.kernel.org, kernel-team@meta.com, 'Amery Hung ' Subject: [RFC PATCH bpf-next 09/12] bpf: Add bpf_list_{front,back} kfunc Date: Fri, 18 Apr 2025 15:46:47 -0700 Message-ID: <20250418224652.105998-10-martin.lau@linux.dev> In-Reply-To: <20250418224652.105998-1-martin.lau@linux.dev> References: <20250418224652.105998-1-martin.lau@linux.dev> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Martin KaFai Lau In the kernel fq qdisc implementation, it only needs to look at the fields of the first node in a list but does not always need to remove it from the list. It is more convenient to have a peek kfunc for the list. It works similar to the bpf_rbtree_first(). This patch adds bpf_list_{front,back} kfunc. The verifier is changed such that the kfunc returning "struct bpf_list_node *" will be marked as non-owning. The exception is the KF_ACQUIRE kfunc. The net effect is only the new bpf_list_{front,back} kfuncs will have its return pointer marked as non-owning. Signed-off-by: Martin KaFai Lau --- kernel/bpf/helpers.c | 22 ++++++++++++++++++++++ kernel/bpf/verifier.c | 12 ++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 36150d340c16..78cefb41266a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2293,6 +2293,26 @@ __bpf_kfunc struct bpf_list_node *bpf_list_pop_back(struct bpf_list_head *head) return __bpf_list_del(head, true); } +__bpf_kfunc struct bpf_list_node *bpf_list_front(struct bpf_list_head *head) +{ + struct list_head *h = (struct list_head *)head; + + if (list_empty(h) || unlikely(!h->next)) + return NULL; + + return (struct bpf_list_node *)h->next; +} + +__bpf_kfunc struct bpf_list_node *bpf_list_back(struct bpf_list_head *head) +{ + struct list_head *h = (struct list_head *)head; + + if (list_empty(h) || unlikely(!h->next)) + return NULL; + + return (struct bpf_list_node *)h->prev; +} + __bpf_kfunc struct bpf_rb_node *bpf_rbtree_remove(struct bpf_rb_root *root, struct bpf_rb_node *node) { @@ -3236,6 +3256,8 @@ BTF_ID_FLAGS(func, bpf_list_push_front_impl) BTF_ID_FLAGS(func, bpf_list_push_back_impl) BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_list_pop_back, KF_ACQUIRE | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_list_front, KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_list_back, KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_release, KF_RELEASE) BTF_ID_FLAGS(func, bpf_rbtree_remove, KF_ACQUIRE | KF_RET_NULL) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index aacde0274e0f..78a9b3d1cd29 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12079,6 +12079,8 @@ enum special_kfunc_type { KF_bpf_list_push_back_impl, KF_bpf_list_pop_front, KF_bpf_list_pop_back, + KF_bpf_list_front, + KF_bpf_list_back, KF_bpf_cast_to_kern_ctx, KF_bpf_rdonly_cast, KF_bpf_rcu_read_lock, @@ -12124,6 +12126,8 @@ BTF_ID(func, bpf_list_push_front_impl) BTF_ID(func, bpf_list_push_back_impl) BTF_ID(func, bpf_list_pop_front) BTF_ID(func, bpf_list_pop_back) +BTF_ID(func, bpf_list_front) +BTF_ID(func, bpf_list_back) BTF_ID(func, bpf_cast_to_kern_ctx) BTF_ID(func, bpf_rdonly_cast) BTF_ID(func, bpf_rbtree_remove) @@ -12160,6 +12164,8 @@ BTF_ID(func, bpf_list_push_front_impl) BTF_ID(func, bpf_list_push_back_impl) BTF_ID(func, bpf_list_pop_front) BTF_ID(func, bpf_list_pop_back) +BTF_ID(func, bpf_list_front) +BTF_ID(func, bpf_list_back) BTF_ID(func, bpf_cast_to_kern_ctx) BTF_ID(func, bpf_rdonly_cast) BTF_ID(func, bpf_rcu_read_lock) @@ -12598,7 +12604,9 @@ static bool is_bpf_list_api_kfunc(u32 btf_id) return btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] || btf_id == special_kfunc_list[KF_bpf_list_push_back_impl] || btf_id == special_kfunc_list[KF_bpf_list_pop_front] || - btf_id == special_kfunc_list[KF_bpf_list_pop_back]; + btf_id == special_kfunc_list[KF_bpf_list_pop_back] || + btf_id == special_kfunc_list[KF_bpf_list_front] || + btf_id == special_kfunc_list[KF_bpf_list_back]; } static bool is_bpf_rbtree_api_kfunc(u32 btf_id) @@ -13902,7 +13910,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (is_kfunc_ret_null(&meta)) regs[BPF_REG_0].id = id; regs[BPF_REG_0].ref_obj_id = id; - } else if (is_rbtree_node_type(ptr_type)) { + } else if (is_rbtree_node_type(ptr_type) || is_list_node_type(ptr_type)) { ref_set_non_owning(env, ®s[BPF_REG_0]); } -- 2.47.1