From patchwork Thu Mar 16 01:41:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13176912 X-Patchwork-Delegate: bpf@iogearbox.net 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 4D64DC61DA4 for ; Thu, 16 Mar 2023 01:41:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229872AbjCPBll (ORCPT ); Wed, 15 Mar 2023 21:41:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229459AbjCPBlg (ORCPT ); Wed, 15 Mar 2023 21:41:36 -0400 Received: from mail-qt1-f179.google.com (mail-qt1-f179.google.com [209.85.160.179]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F4207B7D89; Wed, 15 Mar 2023 18:41:31 -0700 (PDT) Received: by mail-qt1-f179.google.com with SMTP id c18so277329qte.5; Wed, 15 Mar 2023 18:41:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678930890; 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=x5WS6KKdTFofb6bEzbdOSRo28ZlNPT8Pg4JD2YjEh/o=; b=dxZM2Ru5wkdwrm70UKwkWC/QWBoKkFZk9jt0ESDRPwF9OrgK05bI7qcInPmSabuwMr msfT/qZbSIFEoewzJTF4pIeM/qCsUlO7+8PIPh2LKrexM9iEyyw5b6JMNINPFfB8r9cu KGT0SvQNQFEoZrRBBbBsVcIJyW2XTjy6pA1VaiMpFh+96eonDdIwcaFcsKCJlEZZkPk+ ycfIpLojSN3599IMeIq0M/4FqNG1fhKJwk03TZTR976IXDwk6u04kydSSWJp1dXduOxI l9Hwch57+80rA4qqP/1+dfUqK/4I/AfCKu5OGeHWezFYDMsK1WCE3Cbr/qL1V0nxyOHJ R+Dw== X-Gm-Message-State: AO0yUKUXvq7SprnoQQPFAazWJbCWtohdtFEHmgXHZ0AzpItwaXrLMUIb ZqX6+Nnp02YmhucKygc2jhtjKbwECToyWgWX X-Google-Smtp-Source: AK7set+62/FUD1hxv9bzam/0biCdSALeg9Mog6Spcx9nOiVx9MjxbxPoD/vRyBsjvg7+Zy7w6dDspA== X-Received: by 2002:ac8:7d02:0:b0:3bf:daae:7f2a with SMTP id g2-20020ac87d02000000b003bfdaae7f2amr3221891qtb.68.1678930889901; Wed, 15 Mar 2023 18:41:29 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:5c58]) by smtp.gmail.com with ESMTPSA id c1-20020ac853c1000000b003bfc1f49ad1sm4938505qtq.87.2023.03.15.18.41.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Mar 2023 18:41:29 -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, yhs@meta.com, 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 Subject: [PATCH bpf-next 4/5] bpf: Remove bpf_cpumask_kptr_get() kfunc Date: Wed, 15 Mar 2023 20:41:21 -0500 Message-Id: <20230316014122.678082-5-void@manifault.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230316014122.678082-1-void@manifault.com> References: <20230316014122.678082-1-void@manifault.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Now that struct bpf_cpumask is RCU safe, there's no need for this kfunc. Rather than doing the following: private(MASK) static struct bpf_cpumask __kptr *global; int BPF_PROG(prog, s32 cpu, ...) { struct bpf_cpumask *cpumask; bpf_rcu_read_lock(); cpumask = bpf_cpumask_kptr_get(&global); if (!cpumask) { bpf_rcu_read_unlock(); return -1; } bpf_cpumask_setall(cpumask); ... bpf_cpumask_release(cpumask); bpf_rcu_read_unlock(); } Programs can instead simply do this (assume same global cpumask): int BPF_PROG(prog, ...) { struct bpf_cpumask *cpumask; bpf_rcu_read_lock(); cpumask = global; if (!cpumask) { bpf_rcu_read_unlock(); return -1; } bpf_cpumask_setall(cpumask); ... bpf_rcu_read_unlock(); } In other words, no extra atomic acquire / release, and less boilerplate code. This patch removes both the kfunc, and its selftests. A subsequent patch will update the BPF documentation to use the new method for accessing cpumasks with RCU protection. Signed-off-by: David Vernet --- kernel/bpf/cpumask.c | 29 ------------------ .../selftests/bpf/prog_tests/cpumask.c | 1 - .../selftests/bpf/progs/cpumask_common.h | 1 - .../selftests/bpf/progs/cpumask_failure.c | 24 --------------- .../selftests/bpf/progs/cpumask_success.c | 30 ------------------- 5 files changed, 85 deletions(-) diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index 9ab462c5848a..5329d07114e9 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -81,34 +81,6 @@ __bpf_kfunc struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask) return cpumask; } -/** - * bpf_cpumask_kptr_get() - Attempt to acquire a reference to a BPF cpumask - * stored in a map. - * @cpumaskp: A pointer to a BPF cpumask map value. - * - * Attempts to acquire a reference to a BPF cpumask stored in a map value. The - * cpumask returned by this function must either be embedded in a map as a - * kptr, or freed with bpf_cpumask_release(). This function may return NULL if - * no BPF cpumask was found in the specified map value. - */ -__bpf_kfunc struct bpf_cpumask *bpf_cpumask_kptr_get(struct bpf_cpumask **cpumaskp) -{ - struct bpf_cpumask *cpumask; - - /* The BPF memory allocator frees memory backing its caches in an RCU - * callback. Thus, we can safely use RCU to ensure that the cpumask is - * safe to read. - */ - rcu_read_lock(); - - cpumask = READ_ONCE(*cpumaskp); - if (cpumask && !refcount_inc_not_zero(&cpumask->usage)) - cpumask = NULL; - - rcu_read_unlock(); - return cpumask; -} - static void cpumask_free_cb(struct rcu_head *head) { struct bpf_cpumask *cpumask; @@ -434,7 +406,6 @@ BTF_SET8_START(cpumask_kfunc_btf_ids) BTF_ID_FLAGS(func, bpf_cpumask_create, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cpumask_release, KF_RELEASE | KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_cpumask_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) -BTF_ID_FLAGS(func, bpf_cpumask_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cpumask_first, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_first_zero, KF_RCU) BTF_ID_FLAGS(func, bpf_cpumask_set_cpu, KF_RCU) diff --git a/tools/testing/selftests/bpf/prog_tests/cpumask.c b/tools/testing/selftests/bpf/prog_tests/cpumask.c index 6c0fe23498c7..cdf4acc18e4c 100644 --- a/tools/testing/selftests/bpf/prog_tests/cpumask.c +++ b/tools/testing/selftests/bpf/prog_tests/cpumask.c @@ -16,7 +16,6 @@ static const char * const cpumask_success_testcases[] = { "test_copy_any_anyand", "test_insert_leave", "test_insert_remove_release", - "test_insert_kptr_get_release", "test_global_mask_rcu", }; diff --git a/tools/testing/selftests/bpf/progs/cpumask_common.h b/tools/testing/selftests/bpf/progs/cpumask_common.h index 7623782fbd62..0c5b785a93e4 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_common.h +++ b/tools/testing/selftests/bpf/progs/cpumask_common.h @@ -26,7 +26,6 @@ struct array_map { struct bpf_cpumask *bpf_cpumask_create(void) __ksym; void bpf_cpumask_release(struct bpf_cpumask *cpumask) __ksym; struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask) __ksym; -struct bpf_cpumask *bpf_cpumask_kptr_get(struct bpf_cpumask **cpumask) __ksym; u32 bpf_cpumask_first(const struct cpumask *cpumask) __ksym; u32 bpf_cpumask_first_zero(const struct cpumask *cpumask) __ksym; void bpf_cpumask_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) __ksym; diff --git a/tools/testing/selftests/bpf/progs/cpumask_failure.c b/tools/testing/selftests/bpf/progs/cpumask_failure.c index 9f726d55f747..db4f94e72b61 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_failure.c +++ b/tools/testing/selftests/bpf/progs/cpumask_failure.c @@ -94,30 +94,6 @@ int BPF_PROG(test_insert_remove_no_release, struct task_struct *task, u64 clone_ return 0; } -SEC("tp_btf/task_newtask") -__failure __msg("Unreleased reference") -int BPF_PROG(test_kptr_get_no_release, struct task_struct *task, u64 clone_flags) -{ - struct bpf_cpumask *cpumask; - struct __cpumask_map_value *v; - - cpumask = create_cpumask(); - if (!cpumask) - return 0; - - if (cpumask_map_insert(cpumask)) - return 0; - - v = cpumask_map_value_lookup(); - if (!v) - return 0; - - cpumask = bpf_cpumask_kptr_get(&v->cpumask); - - /* cpumask is never released. */ - return 0; -} - SEC("tp_btf/task_newtask") __failure __msg("NULL pointer passed to trusted arg0") int BPF_PROG(test_cpumask_null, struct task_struct *task, u64 clone_flags) diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c index fe928ff72a06..2fcdd7f68ac7 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_success.c +++ b/tools/testing/selftests/bpf/progs/cpumask_success.c @@ -394,36 +394,6 @@ int BPF_PROG(test_insert_remove_release, struct task_struct *task, u64 clone_fla return 0; } -SEC("tp_btf/task_newtask") -int BPF_PROG(test_insert_kptr_get_release, struct task_struct *task, u64 clone_flags) -{ - struct bpf_cpumask *cpumask; - struct __cpumask_map_value *v; - - cpumask = create_cpumask(); - if (!cpumask) - return 0; - - if (cpumask_map_insert(cpumask)) { - err = 3; - return 0; - } - - v = cpumask_map_value_lookup(); - if (!v) { - err = 4; - return 0; - } - - cpumask = bpf_cpumask_kptr_get(&v->cpumask); - if (cpumask) - bpf_cpumask_release(cpumask); - else - err = 5; - - return 0; -} - SEC("tp_btf/task_newtask") int BPF_PROG(test_global_mask_rcu, struct task_struct *task, u64 clone_flags) {