From patchwork Thu Jan 19 23:58:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13108996 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 195AAC004D4 for ; Thu, 19 Jan 2023 23:59:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230467AbjASX7b (ORCPT ); Thu, 19 Jan 2023 18:59:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230418AbjASX7L (ORCPT ); Thu, 19 Jan 2023 18:59:11 -0500 Received: from mail-qt1-f172.google.com (mail-qt1-f172.google.com [209.85.160.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43F6C9FDF7; Thu, 19 Jan 2023 15:58:49 -0800 (PST) Received: by mail-qt1-f172.google.com with SMTP id q15so3025262qtn.0; Thu, 19 Jan 2023 15:58:49 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=Dq/XFjJnJiWbDVyC0d12Dhba4pfFkLwME1GhoxP6Zr4=; b=BNrRi02dHCwB2lv7OxFzoVLL1Sa6RE6NoVslBsDOxR2xuuA7pZGPGqISkrXF2LHiYx 1cFDgZwR6cUBxs7mV5e5tUbEK8mPSyAbEpmViNEPdL42ZpFfTlaj8rRXsUny9VURm/CU Ym8irZEkOGoNkbJGqc1MUSeV2tJ44P9wIuGeGMyknF/O3ZNn600wVm4Xqox5kuzbcmf2 H0t89MGiL934709PC7zYDpJmQTlhayoYdCEZ6JQZXigE0cWZE3eNHDdgjykMjpYjGQyQ 6wCZM6cckZG4f29hYd8MgSB5IQKMVgdvNjKzkBBRRFntmw0533Ja6WHnDzg8ATvTFlsr QF0g== X-Gm-Message-State: AFqh2kpvVMgwEw1OsaScg1Zt26jqT7+qLeN0vWGJHcV02N6HdQf+HEES PsislVQKDrMfxelrTfH4v0WWg0uHBPOxkCul X-Google-Smtp-Source: AMrXdXsVxDrXoeV8LGOgsmvO7Q+4VbwzvUxEEtrRizbIH/2dc76/jZdxztBeYd3AAT4Mj/c43DVAiw== X-Received: by 2002:ac8:6a0e:0:b0:3ab:7928:526c with SMTP id t14-20020ac86a0e000000b003ab7928526cmr16642343qtr.17.1674172727437; Thu, 19 Jan 2023 15:58:47 -0800 (PST) Received: from localhost ([2620:10d:c091:480::1:2fc9]) by smtp.gmail.com with ESMTPSA id b5-20020a05620a04e500b006ee8874f5fasm24356275qkh.53.2023.01.19.15.58.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Jan 2023 15:58:46 -0800 (PST) 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, tj@kernel.org Subject: [PATCH bpf-next 7/8] bpf/docs: Document cpumask kfuncs in a new file Date: Thu, 19 Jan 2023 17:58:32 -0600 Message-Id: <20230119235833.2948341-8-void@manifault.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230119235833.2948341-1-void@manifault.com> References: <20230119235833.2948341-1-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 we've added a series of new cpumask kfuncs, we should document them so users can easily use them. This patch adds a new cpumasks.rst file to document them. Signed-off-by: David Vernet --- Documentation/bpf/cpumasks.rst | 357 +++++++++++++++++++++++++++++++++ Documentation/bpf/index.rst | 1 + Documentation/bpf/kfuncs.rst | 11 + kernel/bpf/cpumask.c | 208 +++++++++++++++++++ 4 files changed, 577 insertions(+) create mode 100644 Documentation/bpf/cpumasks.rst diff --git a/Documentation/bpf/cpumasks.rst b/Documentation/bpf/cpumasks.rst new file mode 100644 index 000000000000..ae6238965c50 --- /dev/null +++ b/Documentation/bpf/cpumasks.rst @@ -0,0 +1,357 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _cpumasks-header-label: + +================== +BPF cpumask kfuncs +================== + +1. Introduction +=============== + +``struct cpumask`` is a bitmap data structure in the kernel whose indices +reflect the CPUs on the system. Commonly, cpumasks are used to track which CPUs +a task is affinitized to, but they can also be used to e.g. track which cores +are associated with a scheduling domain, which cores on a machine are idle, +etc. + +BPF provides programs with a set of :ref:`kfuncs-header-label` that can be +used to allocate, mutate, query, and free cpumasks. + +2. BPF cpumask objects +====================== + +There are two different types of cpumasks that can be used by BPF programs. + +2.1 ``struct bpf_cpumask *`` +---------------------------- + +``struct bpf_cpumask *`` is a cpumask that is allocated by BPF, on behalf of a +BPF program, and whose lifecycle is entirely controlled by BPF. These cpumasks +are RCU-protected, can be mutated, can be used as kptrs, and can be safely cast +to a ``struct cpumask *``. + +2.1.1 ``struct bpf_cpumask *`` lifecycle +---------------------------------------- + +A ``struct bpf_cpumask *`` is allocated, acquired, and released, using the +following functions: + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_create + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_acquire + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_release + +For example: + +.. code-block:: c + + /** + * A trivial example tracepoint program that shows how to + * acquire and release a struct bpf_cpumask *. + */ + SEC("tp_btf/task_newtask") + int BPF_PROG(task_acquire_release_example, struct task_struct *task, u64 clone_flags) + { + struct bpf_cpumask *cpumask, *acquired; + + cpumask = bpf_cpumask_create(); + if (!cpumask) + return 1; + + acquired = bpf_cpumask_acquire(cpumask); + bpf_cpumask_release(cpumask); + bpf_cpumask_acquire(acquired); + + return 0; + } + +---- + +2.1.1 ``struct bpf_cpumask *`` as kptrs +--------------------------------------- + +As mentioned above, these ``struct bpf_cpumask *`` objects can also be stored +in a map and used as kptrs. If a ``struct bpf_cpumask *`` is in a map, the +reference can be removed from the map with bpf_kptr_xchg(), or +opportunistically acquired with bpf_cpumask_kptr_get(): + + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_kptr_get + +Here is an example of a ``struct bpf_cpumask *`` being retrieved from a map: + +.. code-block:: c + + /* struct containing the struct bpf_cpumask kptr which is actually stored in the map. */ + struct __bpf_cpumasks_kfunc_map_value { + struct bpf_cpumask __kptr_ref * bpf_cpumask; + }; + + /* The map containing struct __bpf_cpumasks_kfunc_map_value entries. */ + struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, struct __bpf_cpumasks_kfunc_map_value); + __uint(max_entries, 1); + } __bpf_cpumasks_kfunc_map SEC(".maps"); + + /* ... */ + + /** + * A simple example tracepoint program showing how a + * struct bpf_cpumask * kptr that is stored in a map can + * be acquired using the bpf_cpumask_kptr_get() kfunc. + */ + SEC("tp_btf/cgroup_mkdir") + int BPF_PROG(cgrp_ancestor_example, struct cgroup *cgrp, const char *path) + { + struct bpf_cpumask *kptr; + struct __bpf_cpumasks_kfunc_map_value *v; + u32 key = 0; + + /* Assume a bpf_cpumask * kptr was previously stored in the map. */ + v = bpf_map_lookup_elem(&__bpf_cpumasks_kfunc_map, &key); + if (!v) + return -ENOENT; + + /* Acquire a reference to the bpf_cpumask * kptr that's already stored in the map. */ + kptr = bpf_cpumask_kptr_get(&v->cpumask); + if (!kptr) + /* If no bpf_cpumask was present in the map, it's because + * we're racing with another CPU that removed it with + * bpf_kptr_xchg() between the bpf_map_lookup_elem() + * above, and our call to bpf_cpumask_kptr_get(). + * bpf_cpumask_kptr_get() internally safely handles this + * race, and will return NULL if the cpumask is no longer + * present in the map by the time we invoke the kfunc. + */ + return -EBUSY; + + /* Free the reference we just took above. Note that the + * original struct bpf_cpumask * kptr is still in the map. It will + * be freed either at a later time if another context deletes + * it from the map, or automatically by the BPF subsystem if + * it's still present when the map is destroyed. + */ + bpf_cpumask_release(kptr); + + return 0; + } + +---- + +2.2 ``struct cpumask`` +---------------------- + +``struct cpumask`` is the object that actually contains the cpumask bitmap +being queried, mutated, etc. A ``struct bpf_cpumask`` wraps a ``struct +cpumask``, which is why it's safe to cast it as such (note however that it is +**not** safe to cast a ``struct cpumask *`` to a ``struct bpf_cpumask *``, and +the verifier will reject any program that tries to do so). + +As we'll see below, any kfunc that mutates its cpumask argument will take a +``struct bpf_cpumask *`` as that argument. Any argument that simply queries the +cpumask will instead take a ``struct cpumask *``. + +3. cpumask kfuncs +================= + +Above, we described the kfuncs that can be used to allocate, acquire, release, +etc a ``struct bpf_cpumask *``. This section of the document will describe the +kfuncs for mutating and querying cpumasks. + +3.1 Mutating cpumasks +--------------------- + +Some cpumask kfuncs are "read-only" in that they don't mutate any of their +arguments, whereas others mutate at least one argument (which means that the +argument must be a ``struct bpf_cpumask *``, as described above). + +This section will describe all of the cpumask kfuncs which mutate at least one +argument. :ref:`cpumasks-querying-label` below describes the read-only kfuncs. + +3.1.1 Setting and clearing CPUs +------------------------------- + +bpf_cpumask_set_cpu() and bpf_cpumask_clear_cpu() can be used to set and clear +a CPU in a ``struct bpf_cpumask`` respectively: + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_set_cpu bpf_cpumask_clear_cpu + +These kfuncs are pretty straightforward, and can be used, for example, as +follows: + +.. code-block:: c + + /** + * A sample tracepoint showing how a cpumask can be queried. + */ + SEC("tp_btf/task_newtask") + int BPF_PROG(test_set_clear_cpu, struct task_struct *task, u64 clone_flags) + { + struct bpf_cpumask *cpumask; + + cpumask = bpf_cpumask_create(); + if (!cpumask) + return -ENOMEM; + + bpf_cpumask_set_cpu(0, cpumask); + if (!bpf_cpumask_test_cpu(0, cast(cpumask))) + /* Should never happen. */ + goto release_exit; + + bpf_cpumask_clear_cpu(0, cpumask); + if (bpf_cpumask_test_cpu(0, cast(cpumask))) + /* Should never happen. */ + goto release_exit; + + /* struct cpumask * pointers such as task->cpus_ptr can also be queried. */ + if (bpf_cpumask_test_cpu(0, task->cpus_ptr)) + bpf_printk("task %s can use CPU %d", task->comm, 0); + + release_exit: + bpf_cpumask_release(cpumask); + return 0; + } + +---- + +bpf_cpumask_test_and_set_cpu() and bpf_cpumask_test_and_clear_cpu() are +analogous kfuncs that allow callers to atomically test and set (or clear) CPUs: + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_test_and_set_cpu bpf_cpumask_test_and_clear_cpu + +---- + +We can also set and clear entire ``struct bpf_cpumask *`` objects in one +operation using bpf_cpumask_setall() and bpf_cpumask_clear(): + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_setall bpf_cpumask_clear + +3.1.2 Operations between cpumasks +--------------------------------- + +In addition to setting and clearing individual CPUs in a single cpumask, +callers can also perform bitwise operations between multiple cpumasks using +bpf_cpumask_and(), bpf_cpumask_or(), and bpf_cpumask_xor(): + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_and bpf_cpumask_or bpf_cpumask_xor + +The following is an example of how they may be used. Note that some of the +kfuncs shown in this example will be covered in more detail below. + +.. code-block:: c + + /** + * A sample tracepoint showing how a cpumask can be mutated using + bitwise operators (and queried). + */ + SEC("tp_btf/task_newtask") + int BPF_PROG(test_set_clear_cpu, struct task_struct *task, u64 clone_flags) + { + struct bpf_cpumask *mask1, *mask2, *dst1, *dst2; + int ret = -EINVAL; + + mask1 = bpf_cpumask_create(); + if (!mask1) + return -ENOMEM; + + mask2 = bpf_cpumask_create(); + if (!mask2) { + bpf_cpumask_release(mask1); + return -ENOMEM; + } + + // ...Safely create the other two masks... */ + + bpf_cpumask_set_cpu(0, mask1); + bpf_cpumask_set_cpu(1, mask2); + bpf_cpumask_and(dst1, (const struct cpumask *)mask1, (const struct cpumask *)mask2); + if (!bpf_cpumask_empty((const struct cpumask *)dst1)) + /* Should never happen. */ + goto release_exit; + + bpf_cpumask_or(dst1, (const struct cpumask *)mask1, (const struct cpumask *)mask2); + if (!bpf_cpumask_test_cpu(0, (const struct cpumask *)dst1)) + /* Should never happen. */ + goto release_exit; + + if (!bpf_cpumask_test_cpu(1, (const struct cpumask *)dst1)) + /* Should never happen. */ + goto release_exit; + + bpf_cpumask_xor(dst2, (const struct cpumask *)mask1, (const struct cpumask *)mask2); + if (!bpf_cpumask_equal((const struct cpumask *)dst1, + (const struct cpumask *)dst2)) + /* Should never happen. */ + goto release_exit; + + err = 0; + + release_exit: + bpf_cpumask_release(mask1); + bpf_cpumask_release(mask2); + bpf_cpumask_release(dst1); + bpf_cpumask_release(dst2); + return 0; + } + +---- + +The contents of an entire cpumask may be copied to another using +bpf_cpumask_copy(): + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_copy + +---- + +.. _cpumasks-querying-label: + +3.2 Querying cpumasks +--------------------- + +In addition to the above kfuncs, there is also a set of read-only kfuncs that +can be used to query the contents of cpumasks. + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_first bpf_cpumask_first_zero bpf_cpumask_test_cpu + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_equal bpf_cpumask_intersects bpf_cpumask_subset + bpf_cpumask_empty bpf_cpumask_full + +.. kernel-doc:: kernel/bpf/cpumask.c + :identifiers: bpf_cpumask_any bpf_cpumask_any_and + +---- + +Some example usages of these querying kfuncs were shown above. We will not +replicate those exmaples here. Note, however, that all of the aforementioned +kfuncs are tested in `tools/testing/selftests/bpf/progs/cpumask_success.c`_, so +please take a look there if you're looking for more examples of how they can be +used. + +.. _tools/testing/selftests/bpf/progs/cpumask_success.c: + https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/bpf/progs/cpumask_success.c + + +4. Adding BPF cpumask kfuncs +============================ + +The set of supported BPF cpumask kfuncs are not (yet) a 1-1 match with the +cpumask operations in include/linux/cpumask.h. Any of those cpumask operations +could easily be encapsulated in a new kfunc if and when required. If you'd like +to support a new cpumask operation, please feel free to submit a patch. If you +do add a new cpumask kfunc, please document it here, and add any relevant +selftest testcases to the cpumask selftest suite. diff --git a/Documentation/bpf/index.rst b/Documentation/bpf/index.rst index b81533d8b061..dbb39e8f9889 100644 --- a/Documentation/bpf/index.rst +++ b/Documentation/bpf/index.rst @@ -20,6 +20,7 @@ that goes into great technical depth about the BPF Architecture. syscall_api helpers kfuncs + cpumasks programs maps bpf_prog_run diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index 9fd7fb539f85..a74f9e74087b 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -1,3 +1,7 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _kfuncs-header-label: + ============================= BPF Kernel Functions (kfuncs) ============================= @@ -420,3 +424,10 @@ the verifier. bpf_cgroup_ancestor() can be used as follows: bpf_cgroup_release(parent); return 0; } + +3.3 struct cpumask * kfuncs +--------------------------- + +BPF provides a set of kfuncs that can be used to query, allocate, mutate, and +destroy struct cpumask * objects. Please refer to :ref:`cpumasks-header-label` +for more details. diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c index e1fa15a7e079..91fdd07ee9fc 100644 --- a/kernel/bpf/cpumask.c +++ b/kernel/bpf/cpumask.c @@ -35,6 +35,16 @@ static bool cpu_valid(u32 cpu) return cpu < nr_cpu_ids; } +/** + * bpf_cpumask_create() - Create a mutable BPF cpumask. + * + * Allocates a cpumask that can be queried, mutated, acquired, and released by + * a BPF program. The cpumask returned by this function must either be embedded + * in a map as a kptr, or freed with bpf_cpumask_release(). + * + * bpf_cpumask_create() allocates memory using the BPF memory allocator, and + * will not block. It may return NULL if no memory is available. + */ struct bpf_cpumask *bpf_cpumask_create(void) { struct bpf_cpumask *cpumask; @@ -49,12 +59,31 @@ struct bpf_cpumask *bpf_cpumask_create(void) return cpumask; } +/** + * bpf_cpumask_acquire() - Acquire a reference to a BPF cpumask. + * @cpumask: The BPF cpumask being acquired. The cpumask must be a trusted + * pointer. + * + * Acquires a reference to a BPF cpumask. The cpumask returned by this function + * must either be embedded in a map as a kptr, or freed with + * bpf_cpumask_release(). + */ struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask) { refcount_inc(&cpumask->usage); 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. + */ struct bpf_cpumask *bpf_cpumask_kptr_get(struct bpf_cpumask **cpumaskp) { struct bpf_cpumask *cpumask; @@ -73,6 +102,14 @@ struct bpf_cpumask *bpf_cpumask_kptr_get(struct bpf_cpumask **cpumaskp) return cpumask; } +/** + * bpf_cpumask_release() - Release a previously acquired BPF cpumask. + * @cpumask: The cpumask being released. + * + * Releases a previously acquired reference to a BPF cpumask. When the final + * reference of the BPF cpumask has been released, it is subsequently freed in + * an RCU callback in the BPF memory allocator. + */ void bpf_cpumask_release(struct bpf_cpumask *cpumask) { if (!cpumask) @@ -85,16 +122,36 @@ void bpf_cpumask_release(struct bpf_cpumask *cpumask) } } +/** + * bpf_cpumask_first() - Get the index of the first nonzero bit in the cpumask. + * @cpumask: The cpumask being queried. + * + * Find the index of the first nonzero bit of the cpumask. A struct bpf_cpumask + * pointer may be safely passed to this function. + */ u32 bpf_cpumask_first(const struct cpumask *cpumask) { return cpumask_first(cpumask); } +/** + * bpf_cpumask_first_zero() - Get the index of the first unset bit in the + * cpumask. + * @cpumask: The cpumask being queried. + * + * Find the index of the first unset bit of the cpumask. A struct bpf_cpumask + * pointer may be safely passed to this function. + */ u32 bpf_cpumask_first_zero(const struct cpumask *cpumask) { return cpumask_first_zero(cpumask); } +/** + * bpf_cpumask_set_cpu() - Set a bit for a CPU in a BPF cpumask. + * @cpu: The CPU to be set in the cpumask. + * @cpumask: The BPF cpumask in which a bit is being set. + */ void bpf_cpumask_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) { if (!cpu_valid(cpu)) @@ -103,6 +160,11 @@ void bpf_cpumask_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) cpumask_set_cpu(cpu, (struct cpumask *)cpumask); } +/** + * bpf_cpumask_clear_cpu() - Clear a bit for a CPU in a BPF cpumask. + * @cpu: The CPU to be cleared from the cpumask. + * @cpumask: The BPF cpumask in which a bit is being cleared. + */ void bpf_cpumask_clear_cpu(u32 cpu, struct bpf_cpumask *cpumask) { if (!cpu_valid(cpu)) @@ -111,6 +173,15 @@ void bpf_cpumask_clear_cpu(u32 cpu, struct bpf_cpumask *cpumask) cpumask_clear_cpu(cpu, (struct cpumask *)cpumask); } +/** + * bpf_cpumask_test_cpu() - Test whether a CPU is set in a cpumask. + * @cpu: The CPU being queried for. + * @cpumask: The cpumask being queried for containing a CPU. + * + * Return: + * * true - @cpu is set in the cpumask + * * false - @cpu was not set in the cpumask, or @cpu is an invalid cpu. + */ bool bpf_cpumask_test_cpu(u32 cpu, const struct cpumask *cpumask) { if (!cpu_valid(cpu)) @@ -119,6 +190,15 @@ bool bpf_cpumask_test_cpu(u32 cpu, const struct cpumask *cpumask) return cpumask_test_cpu(cpu, (struct cpumask *)cpumask); } +/** + * bpf_cpumask_test_and_set_cpu() - Atomically test and set a CPU in a BPF cpumask. + * @cpu: The CPU being set and queried for. + * @cpumask: The BPF cpumask being set and queried for containing a CPU. + * + * Return: + * * true - @cpu is set in the cpumask + * * false - @cpu was not set in the cpumask, or @cpu is invalid. + */ bool bpf_cpumask_test_and_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) { if (!cpu_valid(cpu)) @@ -127,6 +207,16 @@ bool bpf_cpumask_test_and_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) return cpumask_test_and_set_cpu(cpu, (struct cpumask *)cpumask); } +/** + * bpf_cpumask_test_and_clear_cpu() - Atomically test and clear a CPU in a BPF + * cpumask. + * @cpu: The CPU being cleared and queried for. + * @cpumask: The BPF cpumask being cleared and queried for containing a CPU. + * + * Return: + * * true - @cpu is set in the cpumask + * * false - @cpu was not set in the cpumask, or @cpu is invalid. + */ bool bpf_cpumask_test_and_clear_cpu(u32 cpu, struct bpf_cpumask *cpumask) { if (!cpu_valid(cpu)) @@ -135,16 +225,36 @@ bool bpf_cpumask_test_and_clear_cpu(u32 cpu, struct bpf_cpumask *cpumask) return cpumask_test_and_clear_cpu(cpu, (struct cpumask *)cpumask); } +/** + * bpf_cpumask_setall() - Set all of the bits in a BPF cpumask. + * @cpumask: The BPF cpumask having all of its bits set. + */ void bpf_cpumask_setall(struct bpf_cpumask *cpumask) { cpumask_setall((struct cpumask *)cpumask); } +/** + * bpf_cpumask_clear() - Clear all of the bits in a BPF cpumask. + * @cpumask: The BPF cpumask being cleared. + */ void bpf_cpumask_clear(struct bpf_cpumask *cpumask) { cpumask_clear((struct cpumask *)cpumask); } +/** + * bpf_cpumask_and() - AND two cpumasks and store the result. + * @dst: The BPF cpumask where the result is being stored. + * @src1: The first input. + * @src2: The second input. + * + * Return: + * * true - @dst has at least one bit set following the operation + * * false - @dst is empty following the operation + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ bool bpf_cpumask_and(struct bpf_cpumask *dst, const struct cpumask *src1, const struct cpumask *src2) @@ -152,6 +262,14 @@ bool bpf_cpumask_and(struct bpf_cpumask *dst, return cpumask_and((struct cpumask *)dst, src1, src2); } +/** + * bpf_cpumask_or() - OR two cpumasks and store the result. + * @dst: The BPF cpumask where the result is being stored. + * @src1: The first input. + * @src2: The second input. + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ void bpf_cpumask_or(struct bpf_cpumask *dst, const struct cpumask *src1, const struct cpumask *src2) @@ -159,6 +277,14 @@ void bpf_cpumask_or(struct bpf_cpumask *dst, cpumask_or((struct cpumask *)dst, src1, src2); } +/** + * bpf_cpumask_xor() - XOR two cpumasks and store the result. + * @dst: The BPF cpumask where the result is being stored. + * @src1: The first input. + * @src2: The second input. + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ void bpf_cpumask_xor(struct bpf_cpumask *dst, const struct cpumask *src1, const struct cpumask *src2) @@ -166,41 +292,123 @@ void bpf_cpumask_xor(struct bpf_cpumask *dst, cpumask_xor((struct cpumask *)dst, src1, src2); } +/** + * bpf_cpumask_equal() - Check two cpumasks for equality. + * @src1: The first input. + * @src2: The second input. + * + * Return: + * * true - @src1 and @src2 have the same bits set. + * * false - @src1 and @src2 differ in at least one bit. + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ bool bpf_cpumask_equal(const struct cpumask *src1, const struct cpumask *src2) { return cpumask_equal(src1, src2); } +/** + * bpf_cpumask_intersects() - Check two cpumasks for overlap. + * @src1: The first input. + * @src2: The second input. + * + * Return: + * * true - @src1 and @src2 have at least one of the same bits set. + * * false - @src1 and @src2 don't have any of the same bits set. + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ bool bpf_cpumask_intersects(const struct cpumask *src1, const struct cpumask *src2) { return cpumask_intersects(src1, src2); } +/** + * bpf_cpumask_subset() - Check if a cpumask is a subset of another. + * @src1: The first cpumask being checked as a subset. + * @src2: The second cpumask being checked as a superset. + * + * Return: + * * true - All of the bits of @src1 are set in @src2. + * * false - At least one bit in @src1 is not set in @src2. + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ bool bpf_cpumask_subset(const struct cpumask *src1, const struct cpumask *src2) { return cpumask_subset(src1, src2); } +/** + * bpf_cpumask_empty() - Check if a cpumask is empty. + * @cpumask: The cpumask being checked. + * + * Return: + * * true - None of the bits in @cpumask are set. + * * false - At least one bit in @cpumask is set. + * + * A struct bpf_cpumask pointer may be safely passed to @cpumask. + */ bool bpf_cpumask_empty(const struct cpumask *cpumask) { return cpumask_empty(cpumask); } +/** + * bpf_cpumask_full() - Check if a cpumask has all bits set. + * @cpumask: The cpumask being checked. + * + * Return: + * * true - All of the bits in @cpumask are set. + * * false - At least one bit in @cpumask is cleared. + * + * A struct bpf_cpumask pointer may be safely passed to @cpumask. + */ bool bpf_cpumask_full(const struct cpumask *cpumask) { return cpumask_full(cpumask); } +/** + * bpf_cpumask_copy() - Copy the contents of a cpumask into a BPF cpumask. + * @dst: The BPF cpumask being copied into. + * @src: The cpumask being copied. + * + * A struct bpf_cpumask pointer may be safely passed to @src. + */ void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask *src) { cpumask_copy((struct cpumask *)dst, src); } +/** + * bpf_cpumask_any() - Return a random set CPU from a cpumask. + * @cpumask: The cpumask being queried. + * + * Return: + * * A random set bit within [0, num_cpus) if at least one bit is set. + * * >= num_cpus if no bit is set. + * + * A struct bpf_cpumask pointer may be safely passed to @src. + */ u32 bpf_cpumask_any(const struct cpumask *cpumask) { return cpumask_any(cpumask); } +/** + * bpf_cpumask_any_and() - Return a random set CPU from the AND of two + * cpumasks. + * @src1: The first cpumask. + * @src2: The second cpumask. + * + * Return: + * * A random set bit within [0, num_cpus) if at least one bit is set. + * * >= num_cpus if no bit is set. + * + * struct bpf_cpumask pointers may be safely passed to @src1 and @src2. + */ u32 bpf_cpumask_any_and(const struct cpumask *src1, const struct cpumask *src2) { return cpumask_any_and(src1, src2);