Commit bdbda395 authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

bpf/docs: Document cpumask kfuncs in a new file 



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: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-6-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 7b6abcfa

Documentation/bpf/cpumasks.rst

0 → 100644
+393 −0
Original line number Diff line number Diff line 
.. 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



        struct cpumask_map_value {

                struct bpf_cpumask __kptr_ref * cpumask;

        };



        struct array_map {

                __uint(type, BPF_MAP_TYPE_ARRAY);

                __type(key, int);

                __type(value, struct cpumask_map_value);

                __uint(max_entries, 65536);

        } cpumask_map SEC(".maps");



        static int cpumask_map_insert(struct bpf_cpumask *mask, u32 pid)

        {

                struct cpumask_map_value local, *v;

                long status;

                struct bpf_cpumask *old;

                u32 key = pid;



                local.cpumask = NULL;

                status = bpf_map_update_elem(&cpumask_map, &key, &local, 0);

                if (status) {

                        bpf_cpumask_release(mask);

                        return status;

                }



                v = bpf_map_lookup_elem(&cpumask_map, &key);

                if (!v) {

                        bpf_cpumask_release(mask);

                        return -ENOENT;

                }



                old = bpf_kptr_xchg(&v->cpumask, mask);

                if (old)

                        bpf_cpumask_release(old);



                return 0;

        }



        /**

         * A sample tracepoint showing how a task's cpumask can be queried and

         * recorded as a kptr.

         */

        SEC("tp_btf/task_newtask")

        int BPF_PROG(record_task_cpumask, struct task_struct *task, u64 clone_flags)

        {

                struct bpf_cpumask *cpumask;

                int ret;



                cpumask = bpf_cpumask_create();

                if (!cpumask)

                        return -ENOMEM;



                if (!bpf_cpumask_full(task->cpus_ptr))

                        bpf_printk("task %s has CPU affinity", task->comm);



                bpf_cpumask_copy(cpumask, task->cpus_ptr);

                return cpumask_map_insert(cpumask, task->pid);

        }



----



2.1.1 ``struct bpf_cpumask *`` as kptrs

---------------------------------------



As mentioned and illustrated 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 stored in the map. */

	struct cpumasks_kfunc_map_value {

		struct bpf_cpumask __kptr_ref * bpf_cpumask;

	};



	/* The map containing struct cpumasks_kfunc_map_value entries. */

	struct {

		__uint(type, BPF_MAP_TYPE_ARRAY);

		__type(key, int);

		__type(value, struct cpumasks_kfunc_map_value);

		__uint(max_entries, 1);

	} 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 cpumasks_kfunc_map_value *v;

		u32 key = 0;



		/* Assume a bpf_cpumask * kptr was previously stored in the map. */

		v = bpf_map_lookup_elem(&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

complementary 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_and_or_xor, struct task_struct *task, u64 clone_flags)

        {

                struct bpf_cpumask *mask1, *mask2, *dst1, *dst2;



                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;



         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.

Documentation/bpf/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ that goes into great technical depth about the BPF Architecture. 
   syscall_api

   helpers

   kfuncs

   cpumasks

   programs

   maps

   bpf_prog_run

Documentation/bpf/kfuncs.rst

+11 −0
Original line number Diff line number Diff line 
.. 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.

kernel/bpf/cpumask.c

+208 −0
Original line number Diff line number Diff line
@@ -38,6 +38,16 @@ __diag_push(); 
__diag_ignore_all("-Wmissing-prototypes",

		  "Global kfuncs as their definitions will be in BTF");



/**

 * 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;
@@ -52,12 +62,31 @@ 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;
@@ -76,6 +105,14 @@ 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)
@@ -88,16 +125,36 @@ 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))
@@ -106,6 +163,11 @@ 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))
@@ -114,6 +176,15 @@ 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))
@@ -122,6 +193,15 @@ 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))
@@ -130,6 +210,16 @@ 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))
@@ -138,16 +228,36 @@ 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)
@@ -155,6 +265,14 @@ 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)
@@ -162,6 +280,14 @@ 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)
@@ -169,41 +295,123 @@ 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);