Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1158 insertions, 0 deletions

diff --git a/kernel/padata.c b/kernel/padata.c
new file mode 100644
index 0000000000..179fb15180
--- /dev/null
+++ b/kernel/padata.c
@@ -0,0 +1,1158 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * padata.c - generic interface to process data streams in parallel
+ *
+ * See Documentation/core-api/padata.rst for more information.
+ *
+ * Copyright (C) 2008, 2009 secunet Security Networks AG
+ * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
+ *
+ * Copyright (c) 2020 Oracle and/or its affiliates.
+ * Author: Daniel Jordan <daniel.m.jordan@oracle.com>
+ */
+
+#include <linux/completion.h>
+#include <linux/export.h>
+#include <linux/cpumask.h>
+#include <linux/err.h>
+#include <linux/cpu.h>
+#include <linux/padata.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/rcupdate.h>
+
+#define	PADATA_WORK_ONSTACK	1	/* Work's memory is on stack */
+
+struct padata_work {
+	struct work_struct	pw_work;
+	struct list_head	pw_list;  /* padata_free_works linkage */
+	void			*pw_data;
+};
+
+static DEFINE_SPINLOCK(padata_works_lock);
+static struct padata_work *padata_works;
+static LIST_HEAD(padata_free_works);
+
+struct padata_mt_job_state {
+	spinlock_t		lock;
+	struct completion	completion;
+	struct padata_mt_job	*job;
+	int			nworks;
+	int			nworks_fini;
+	unsigned long		chunk_size;
+};
+
+static void padata_free_pd(struct parallel_data *pd);
+static void __init padata_mt_helper(struct work_struct *work);
+
+static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
+{
+	int cpu, target_cpu;
+
+	target_cpu = cpumask_first(pd->cpumask.pcpu);
+	for (cpu = 0; cpu < cpu_index; cpu++)
+		target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);
+
+	return target_cpu;
+}
+
+static int padata_cpu_hash(struct parallel_data *pd, unsigned int seq_nr)
+{
+	/*
+	 * Hash the sequence numbers to the cpus by taking
+	 * seq_nr mod. number of cpus in use.
+	 */
+	int cpu_index = seq_nr % cpumask_weight(pd->cpumask.pcpu);
+
+	return padata_index_to_cpu(pd, cpu_index);
+}
+
+static struct padata_work *padata_work_alloc(void)
+{
+	struct padata_work *pw;
+
+	lockdep_assert_held(&padata_works_lock);
+
+	if (list_empty(&padata_free_works))
+		return NULL;	/* No more work items allowed to be queued. */
+
+	pw = list_first_entry(&padata_free_works, struct padata_work, pw_list);
+	list_del(&pw->pw_list);
+	return pw;
+}
+
+/*
+ * This function is marked __ref because this function may be optimized in such
+ * a way that it directly refers to work_fn's address, which causes modpost to
+ * complain when work_fn is marked __init. This scenario was observed with clang
+ * LTO, where padata_work_init() was optimized to refer directly to
+ * padata_mt_helper() because the calls to padata_work_init() with other work_fn
+ * values were eliminated or inlined.
+ */
+static void __ref padata_work_init(struct padata_work *pw, work_func_t work_fn,
+				   void *data, int flags)
+{
+	if (flags & PADATA_WORK_ONSTACK)
+		INIT_WORK_ONSTACK(&pw->pw_work, work_fn);
+	else
+		INIT_WORK(&pw->pw_work, work_fn);
+	pw->pw_data = data;
+}
+
+static int __init padata_work_alloc_mt(int nworks, void *data,
+				       struct list_head *head)
+{
+	int i;
+
+	spin_lock(&padata_works_lock);
+	/* Start at 1 because the current task participates in the job. */
+	for (i = 1; i < nworks; ++i) {
+		struct padata_work *pw = padata_work_alloc();
+
+		if (!pw)
+			break;
+		padata_work_init(pw, padata_mt_helper, data, 0);
+		list_add(&pw->pw_list, head);
+	}
+	spin_unlock(&padata_works_lock);
+
+	return i;
+}
+
+static void padata_work_free(struct padata_work *pw)
+{
+	lockdep_assert_held(&padata_works_lock);
+	list_add(&pw->pw_list, &padata_free_works);
+}
+
+static void __init padata_works_free(struct list_head *works)
+{
+	struct padata_work *cur, *next;
+
+	if (list_empty(works))
+		return;
+
+	spin_lock(&padata_works_lock);
+	list_for_each_entry_safe(cur, next, works, pw_list) {
+		list_del(&cur->pw_list);
+		padata_work_free(cur);
+	}
+	spin_unlock(&padata_works_lock);
+}
+
+static void padata_parallel_worker(struct work_struct *parallel_work)
+{
+	struct padata_work *pw = container_of(parallel_work, struct padata_work,
+					      pw_work);
+	struct padata_priv *padata = pw->pw_data;
+
+	local_bh_disable();
+	padata->parallel(padata);
+	spin_lock(&padata_works_lock);
+	padata_work_free(pw);
+	spin_unlock(&padata_works_lock);
+	local_bh_enable();
+}
+
+/**
+ * padata_do_parallel - padata parallelization function
+ *
+ * @ps: padatashell
+ * @padata: object to be parallelized
+ * @cb_cpu: pointer to the CPU that the serialization callback function should
+ *          run on.  If it's not in the serial cpumask of @pinst
+ *          (i.e. cpumask.cbcpu), this function selects a fallback CPU and if
+ *          none found, returns -EINVAL.
+ *
+ * The parallelization callback function will run with BHs off.
+ * Note: Every object which is parallelized by padata_do_parallel
+ * must be seen by padata_do_serial.
+ *
+ * Return: 0 on success or else negative error code.
+ */
+int padata_do_parallel(struct padata_shell *ps,
+		       struct padata_priv *padata, int *cb_cpu)
+{
+	struct padata_instance *pinst = ps->pinst;
+	int i, cpu, cpu_index, err;
+	struct parallel_data *pd;
+	struct padata_work *pw;
+
+	rcu_read_lock_bh();
+
+	pd = rcu_dereference_bh(ps->pd);
+
+	err = -EINVAL;
+	if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)
+		goto out;
+
+	if (!cpumask_test_cpu(*cb_cpu, pd->cpumask.cbcpu)) {
+		if (cpumask_empty(pd->cpumask.cbcpu))
+			goto out;
+
+		/* Select an alternate fallback CPU and notify the caller. */
+		cpu_index = *cb_cpu % cpumask_weight(pd->cpumask.cbcpu);
+
+		cpu = cpumask_first(pd->cpumask.cbcpu);
+		for (i = 0; i < cpu_index; i++)
+			cpu = cpumask_next(cpu, pd->cpumask.cbcpu);
+
+		*cb_cpu = cpu;
+	}
+
+	err = -EBUSY;
+	if ((pinst->flags & PADATA_RESET))
+		goto out;
+
+	refcount_inc(&pd->refcnt);
+	padata->pd = pd;
+	padata->cb_cpu = *cb_cpu;
+
+	spin_lock(&padata_works_lock);
+	padata->seq_nr = ++pd->seq_nr;
+	pw = padata_work_alloc();
+	spin_unlock(&padata_works_lock);
+
+	if (!pw) {
+		/* Maximum works limit exceeded, run in the current task. */
+		padata->parallel(padata);
+	}
+
+	rcu_read_unlock_bh();
+
+	if (pw) {
+		padata_work_init(pw, padata_parallel_worker, padata, 0);
+		queue_work(pinst->parallel_wq, &pw->pw_work);
+	}
+
+	return 0;
+out:
+	rcu_read_unlock_bh();
+
+	return err;
+}
+EXPORT_SYMBOL(padata_do_parallel);
+
+/*
+ * padata_find_next - Find the next object that needs serialization.
+ *
+ * Return:
+ * * A pointer to the control struct of the next object that needs
+ *   serialization, if present in one of the percpu reorder queues.
+ * * NULL, if the next object that needs serialization will
+ *   be parallel processed by another cpu and is not yet present in
+ *   the cpu's reorder queue.
+ */
+static struct padata_priv *padata_find_next(struct parallel_data *pd,
+					    bool remove_object)
+{
+	struct padata_priv *padata;
+	struct padata_list *reorder;
+	int cpu = pd->cpu;
+
+	reorder = per_cpu_ptr(pd->reorder_list, cpu);
+
+	spin_lock(&reorder->lock);
+	if (list_empty(&reorder->list)) {
+		spin_unlock(&reorder->lock);
+		return NULL;
+	}
+
+	padata = list_entry(reorder->list.next, struct padata_priv, list);
+
+	/*
+	 * Checks the rare case where two or more parallel jobs have hashed to
+	 * the same CPU and one of the later ones finishes first.
+	 */
+	if (padata->seq_nr != pd->processed) {
+		spin_unlock(&reorder->lock);
+		return NULL;
+	}
+
+	if (remove_object) {
+		list_del_init(&padata->list);
+		++pd->processed;
+		pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false);
+	}
+
+	spin_unlock(&reorder->lock);
+	return padata;
+}
+
+static void padata_reorder(struct parallel_data *pd)
+{
+	struct padata_instance *pinst = pd->ps->pinst;
+	int cb_cpu;
+	struct padata_priv *padata;
+	struct padata_serial_queue *squeue;
+	struct padata_list *reorder;
+
+	/*
+	 * We need to ensure that only one cpu can work on dequeueing of
+	 * the reorder queue the time. Calculating in which percpu reorder
+	 * queue the next object will arrive takes some time. A spinlock
+	 * would be highly contended. Also it is not clear in which order
+	 * the objects arrive to the reorder queues. So a cpu could wait to
+	 * get the lock just to notice that there is nothing to do at the
+	 * moment. Therefore we use a trylock and let the holder of the lock
+	 * care for all the objects enqueued during the holdtime of the lock.
+	 */
+	if (!spin_trylock_bh(&pd->lock))
+		return;
+
+	while (1) {
+		padata = padata_find_next(pd, true);
+
+		/*
+		 * If the next object that needs serialization is parallel
+		 * processed by another cpu and is still on it's way to the
+		 * cpu's reorder queue, nothing to do for now.
+		 */
+		if (!padata)
+			break;
+
+		cb_cpu = padata->cb_cpu;
+		squeue = per_cpu_ptr(pd->squeue, cb_cpu);
+
+		spin_lock(&squeue->serial.lock);
+		list_add_tail(&padata->list, &squeue->serial.list);
+		spin_unlock(&squeue->serial.lock);
+
+		queue_work_on(cb_cpu, pinst->serial_wq, &squeue->work);
+	}
+
+	spin_unlock_bh(&pd->lock);
+
+	/*
+	 * The next object that needs serialization might have arrived to
+	 * the reorder queues in the meantime.
+	 *
+	 * Ensure reorder queue is read after pd->lock is dropped so we see
+	 * new objects from another task in padata_do_serial.  Pairs with
+	 * smp_mb in padata_do_serial.
+	 */
+	smp_mb();
+
+	reorder = per_cpu_ptr(pd->reorder_list, pd->cpu);
+	if (!list_empty(&reorder->list) && padata_find_next(pd, false))
+		queue_work(pinst->serial_wq, &pd->reorder_work);
+}
+
+static void invoke_padata_reorder(struct work_struct *work)
+{
+	struct parallel_data *pd;
+
+	local_bh_disable();
+	pd = container_of(work, struct parallel_data, reorder_work);
+	padata_reorder(pd);
+	local_bh_enable();
+}
+
+static void padata_serial_worker(struct work_struct *serial_work)
+{
+	struct padata_serial_queue *squeue;
+	struct parallel_data *pd;
+	LIST_HEAD(local_list);
+	int cnt;
+
+	local_bh_disable();
+	squeue = container_of(serial_work, struct padata_serial_queue, work);
+	pd = squeue->pd;
+
+	spin_lock(&squeue->serial.lock);
+	list_replace_init(&squeue->serial.list, &local_list);
+	spin_unlock(&squeue->serial.lock);
+
+	cnt = 0;
+
+	while (!list_empty(&local_list)) {
+		struct padata_priv *padata;
+
+		padata = list_entry(local_list.next,
+				    struct padata_priv, list);
+
+		list_del_init(&padata->list);
+
+		padata->serial(padata);
+		cnt++;
+	}
+	local_bh_enable();
+
+	if (refcount_sub_and_test(cnt, &pd->refcnt))
+		padata_free_pd(pd);
+}
+
+/**
+ * padata_do_serial - padata serialization function
+ *
+ * @padata: object to be serialized.
+ *
+ * padata_do_serial must be called for every parallelized object.
+ * The serialization callback function will run with BHs off.
+ */
+void padata_do_serial(struct padata_priv *padata)
+{
+	struct parallel_data *pd = padata->pd;
+	int hashed_cpu = padata_cpu_hash(pd, padata->seq_nr);
+	struct padata_list *reorder = per_cpu_ptr(pd->reorder_list, hashed_cpu);
+	struct padata_priv *cur;
+	struct list_head *pos;
+
+	spin_lock(&reorder->lock);
+	/* Sort in ascending order of sequence number. */
+	list_for_each_prev(pos, &reorder->list) {
+		cur = list_entry(pos, struct padata_priv, list);
+		if (cur->seq_nr < padata->seq_nr)
+			break;
+	}
+	list_add(&padata->list, pos);
+	spin_unlock(&reorder->lock);
+
+	/*
+	 * Ensure the addition to the reorder list is ordered correctly
+	 * with the trylock of pd->lock in padata_reorder.  Pairs with smp_mb
+	 * in padata_reorder.
+	 */
+	smp_mb();
+
+	padata_reorder(pd);
+}
+EXPORT_SYMBOL(padata_do_serial);
+
+static int padata_setup_cpumasks(struct padata_instance *pinst)
+{
+	struct workqueue_attrs *attrs;
+	int err;
+
+	attrs = alloc_workqueue_attrs();
+	if (!attrs)
+		return -ENOMEM;
+
+	/* Restrict parallel_wq workers to pd->cpumask.pcpu. */
+	cpumask_copy(attrs->cpumask, pinst->cpumask.pcpu);
+	err = apply_workqueue_attrs(pinst->parallel_wq, attrs);
+	free_workqueue_attrs(attrs);
+
+	return err;
+}
+
+static void __init padata_mt_helper(struct work_struct *w)
+{
+	struct padata_work *pw = container_of(w, struct padata_work, pw_work);
+	struct padata_mt_job_state *ps = pw->pw_data;
+	struct padata_mt_job *job = ps->job;
+	bool done;
+
+	spin_lock(&ps->lock);
+
+	while (job->size > 0) {
+		unsigned long start, size, end;
+
+		start = job->start;
+		/* So end is chunk size aligned if enough work remains. */
+		size = roundup(start + 1, ps->chunk_size) - start;
+		size = min(size, job->size);
+		end = start + size;
+
+		job->start = end;
+		job->size -= size;
+
+		spin_unlock(&ps->lock);
+		job->thread_fn(start, end, job->fn_arg);
+		spin_lock(&ps->lock);
+	}
+
+	++ps->nworks_fini;
+	done = (ps->nworks_fini == ps->nworks);
+	spin_unlock(&ps->lock);
+
+	if (done)
+		complete(&ps->completion);
+}
+
+/**
+ * padata_do_multithreaded - run a multithreaded job
+ * @job: Description of the job.
+ *
+ * See the definition of struct padata_mt_job for more details.
+ */
+void __init padata_do_multithreaded(struct padata_mt_job *job)
+{
+	/* In case threads finish at different times. */
+	static const unsigned long load_balance_factor = 4;
+	struct padata_work my_work, *pw;
+	struct padata_mt_job_state ps;
+	LIST_HEAD(works);
+	int nworks;
+
+	if (job->size == 0)
+		return;
+
+	/* Ensure at least one thread when size < min_chunk. */
+	nworks = max(job->size / max(job->min_chunk, job->align), 1ul);
+	nworks = min(nworks, job->max_threads);
+
+	if (nworks == 1) {
+		/* Single thread, no coordination needed, cut to the chase. */
+		job->thread_fn(job->start, job->start + job->size, job->fn_arg);
+		return;
+	}
+
+	spin_lock_init(&ps.lock);
+	init_completion(&ps.completion);
+	ps.job	       = job;
+	ps.nworks      = padata_work_alloc_mt(nworks, &ps, &works);
+	ps.nworks_fini = 0;
+
+	/*
+	 * Chunk size is the amount of work a helper does per call to the
+	 * thread function.  Load balance large jobs between threads by
+	 * increasing the number of chunks, guarantee at least the minimum
+	 * chunk size from the caller, and honor the caller's alignment.
+	 */
+	ps.chunk_size = job->size / (ps.nworks * load_balance_factor);
+	ps.chunk_size = max(ps.chunk_size, job->min_chunk);
+	ps.chunk_size = roundup(ps.chunk_size, job->align);
+
+	list_for_each_entry(pw, &works, pw_list)
+		queue_work(system_unbound_wq, &pw->pw_work);
+
+	/* Use the current thread, which saves starting a workqueue worker. */
+	padata_work_init(&my_work, padata_mt_helper, &ps, PADATA_WORK_ONSTACK);
+	padata_mt_helper(&my_work.pw_work);
+
+	/* Wait for all the helpers to finish. */
+	wait_for_completion(&ps.completion);
+
+	destroy_work_on_stack(&my_work.pw_work);
+	padata_works_free(&works);
+}
+
+static void __padata_list_init(struct padata_list *pd_list)
+{
+	INIT_LIST_HEAD(&pd_list->list);
+	spin_lock_init(&pd_list->lock);
+}
+
+/* Initialize all percpu queues used by serial workers */
+static void padata_init_squeues(struct parallel_data *pd)
+{
+	int cpu;
+	struct padata_serial_queue *squeue;
+
+	for_each_cpu(cpu, pd->cpumask.cbcpu) {
+		squeue = per_cpu_ptr(pd->squeue, cpu);
+		squeue->pd = pd;
+		__padata_list_init(&squeue->serial);
+		INIT_WORK(&squeue->work, padata_serial_worker);
+	}
+}
+
+/* Initialize per-CPU reorder lists */
+static void padata_init_reorder_list(struct parallel_data *pd)
+{
+	int cpu;
+	struct padata_list *list;
+
+	for_each_cpu(cpu, pd->cpumask.pcpu) {
+		list = per_cpu_ptr(pd->reorder_list, cpu);
+		__padata_list_init(list);
+	}
+}
+
+/* Allocate and initialize the internal cpumask dependend resources. */
+static struct parallel_data *padata_alloc_pd(struct padata_shell *ps)
+{
+	struct padata_instance *pinst = ps->pinst;
+	struct parallel_data *pd;
+
+	pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
+	if (!pd)
+		goto err;
+
+	pd->reorder_list = alloc_percpu(struct padata_list);
+	if (!pd->reorder_list)
+		goto err_free_pd;
+
+	pd->squeue = alloc_percpu(struct padata_serial_queue);
+	if (!pd->squeue)
+		goto err_free_reorder_list;
+
+	pd->ps = ps;
+
+	if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))
+		goto err_free_squeue;
+	if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL))
+		goto err_free_pcpu;
+
+	cpumask_and(pd->cpumask.pcpu, pinst->cpumask.pcpu, cpu_online_mask);
+	cpumask_and(pd->cpumask.cbcpu, pinst->cpumask.cbcpu, cpu_online_mask);
+
+	padata_init_reorder_list(pd);
+	padata_init_squeues(pd);
+	pd->seq_nr = -1;
+	refcount_set(&pd->refcnt, 1);
+	spin_lock_init(&pd->lock);
+	pd->cpu = cpumask_first(pd->cpumask.pcpu);
+	INIT_WORK(&pd->reorder_work, invoke_padata_reorder);
+
+	return pd;
+
+err_free_pcpu:
+	free_cpumask_var(pd->cpumask.pcpu);
+err_free_squeue:
+	free_percpu(pd->squeue);
+err_free_reorder_list:
+	free_percpu(pd->reorder_list);
+err_free_pd:
+	kfree(pd);
+err:
+	return NULL;
+}
+
+static void padata_free_pd(struct parallel_data *pd)
+{
+	free_cpumask_var(pd->cpumask.pcpu);
+	free_cpumask_var(pd->cpumask.cbcpu);
+	free_percpu(pd->reorder_list);
+	free_percpu(pd->squeue);
+	kfree(pd);
+}
+
+static void __padata_start(struct padata_instance *pinst)
+{
+	pinst->flags |= PADATA_INIT;
+}
+
+static void __padata_stop(struct padata_instance *pinst)
+{
+	if (!(pinst->flags & PADATA_INIT))
+		return;
+
+	pinst->flags &= ~PADATA_INIT;
+
+	synchronize_rcu();
+}
+
+/* Replace the internal control structure with a new one. */
+static int padata_replace_one(struct padata_shell *ps)
+{
+	struct parallel_data *pd_new;
+
+	pd_new = padata_alloc_pd(ps);
+	if (!pd_new)
+		return -ENOMEM;
+
+	ps->opd = rcu_dereference_protected(ps->pd, 1);
+	rcu_assign_pointer(ps->pd, pd_new);
+
+	return 0;
+}
+
+static int padata_replace(struct padata_instance *pinst)
+{
+	struct padata_shell *ps;
+	int err = 0;
+
+	pinst->flags |= PADATA_RESET;
+
+	list_for_each_entry(ps, &pinst->pslist, list) {
+		err = padata_replace_one(ps);
+		if (err)
+			break;
+	}
+
+	synchronize_rcu();
+
+	list_for_each_entry_continue_reverse(ps, &pinst->pslist, list)
+		if (refcount_dec_and_test(&ps->opd->refcnt))
+			padata_free_pd(ps->opd);
+
+	pinst->flags &= ~PADATA_RESET;
+
+	return err;
+}
+
+/* If cpumask contains no active cpu, we mark the instance as invalid. */
+static bool padata_validate_cpumask(struct padata_instance *pinst,
+				    const struct cpumask *cpumask)
+{
+	if (!cpumask_intersects(cpumask, cpu_online_mask)) {
+		pinst->flags |= PADATA_INVALID;
+		return false;
+	}
+
+	pinst->flags &= ~PADATA_INVALID;
+	return true;
+}
+
+static int __padata_set_cpumasks(struct padata_instance *pinst,
+				 cpumask_var_t pcpumask,
+				 cpumask_var_t cbcpumask)
+{
+	int valid;
+	int err;
+
+	valid = padata_validate_cpumask(pinst, pcpumask);
+	if (!valid) {
+		__padata_stop(pinst);
+		goto out_replace;
+	}
+
+	valid = padata_validate_cpumask(pinst, cbcpumask);
+	if (!valid)
+		__padata_stop(pinst);
+
+out_replace:
+	cpumask_copy(pinst->cpumask.pcpu, pcpumask);
+	cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
+
+	err = padata_setup_cpumasks(pinst) ?: padata_replace(pinst);
+
+	if (valid)
+		__padata_start(pinst);
+
+	return err;
+}
+
+/**
+ * padata_set_cpumask - Sets specified by @cpumask_type cpumask to the value
+ *                      equivalent to @cpumask.
+ * @pinst: padata instance
+ * @cpumask_type: PADATA_CPU_SERIAL or PADATA_CPU_PARALLEL corresponding
+ *                to parallel and serial cpumasks respectively.
+ * @cpumask: the cpumask to use
+ *
+ * Return: 0 on success or negative error code
+ */
+int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
+		       cpumask_var_t cpumask)
+{
+	struct cpumask *serial_mask, *parallel_mask;
+	int err = -EINVAL;
+
+	cpus_read_lock();
+	mutex_lock(&pinst->lock);
+
+	switch (cpumask_type) {
+	case PADATA_CPU_PARALLEL:
+		serial_mask = pinst->cpumask.cbcpu;
+		parallel_mask = cpumask;
+		break;
+	case PADATA_CPU_SERIAL:
+		parallel_mask = pinst->cpumask.pcpu;
+		serial_mask = cpumask;
+		break;
+	default:
+		 goto out;
+	}
+
+	err =  __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
+
+out:
+	mutex_unlock(&pinst->lock);
+	cpus_read_unlock();
+
+	return err;
+}
+EXPORT_SYMBOL(padata_set_cpumask);
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
+{
+	int err = 0;
+
+	if (cpumask_test_cpu(cpu, cpu_online_mask)) {
+		err = padata_replace(pinst);
+
+		if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) &&
+		    padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
+			__padata_start(pinst);
+	}
+
+	return err;
+}
+
+static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
+{
+	int err = 0;
+
+	if (!cpumask_test_cpu(cpu, cpu_online_mask)) {
+		if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) ||
+		    !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
+			__padata_stop(pinst);
+
+		err = padata_replace(pinst);
+	}
+
+	return err;
+}
+
+static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu)
+{
+	return cpumask_test_cpu(cpu, pinst->cpumask.pcpu) ||
+		cpumask_test_cpu(cpu, pinst->cpumask.cbcpu);
+}
+
+static int padata_cpu_online(unsigned int cpu, struct hlist_node *node)
+{
+	struct padata_instance *pinst;
+	int ret;
+
+	pinst = hlist_entry_safe(node, struct padata_instance, cpu_online_node);
+	if (!pinst_has_cpu(pinst, cpu))
+		return 0;
+
+	mutex_lock(&pinst->lock);
+	ret = __padata_add_cpu(pinst, cpu);
+	mutex_unlock(&pinst->lock);
+	return ret;
+}
+
+static int padata_cpu_dead(unsigned int cpu, struct hlist_node *node)
+{
+	struct padata_instance *pinst;
+	int ret;
+
+	pinst = hlist_entry_safe(node, struct padata_instance, cpu_dead_node);
+	if (!pinst_has_cpu(pinst, cpu))
+		return 0;
+
+	mutex_lock(&pinst->lock);
+	ret = __padata_remove_cpu(pinst, cpu);
+	mutex_unlock(&pinst->lock);
+	return ret;
+}
+
+static enum cpuhp_state hp_online;
+#endif
+
+static void __padata_free(struct padata_instance *pinst)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+	cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD,
+					    &pinst->cpu_dead_node);
+	cpuhp_state_remove_instance_nocalls(hp_online, &pinst->cpu_online_node);
+#endif
+
+	WARN_ON(!list_empty(&pinst->pslist));
+
+	free_cpumask_var(pinst->cpumask.pcpu);
+	free_cpumask_var(pinst->cpumask.cbcpu);
+	destroy_workqueue(pinst->serial_wq);
+	destroy_workqueue(pinst->parallel_wq);
+	kfree(pinst);
+}
+
+#define kobj2pinst(_kobj)					\
+	container_of(_kobj, struct padata_instance, kobj)
+#define attr2pentry(_attr)					\
+	container_of(_attr, struct padata_sysfs_entry, attr)
+
+static void padata_sysfs_release(struct kobject *kobj)
+{
+	struct padata_instance *pinst = kobj2pinst(kobj);
+	__padata_free(pinst);
+}
+
+struct padata_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct padata_instance *, struct attribute *, char *);
+	ssize_t (*store)(struct padata_instance *, struct attribute *,
+			 const char *, size_t);
+};
+
+static ssize_t show_cpumask(struct padata_instance *pinst,
+			    struct attribute *attr,  char *buf)
+{
+	struct cpumask *cpumask;
+	ssize_t len;
+
+	mutex_lock(&pinst->lock);
+	if (!strcmp(attr->name, "serial_cpumask"))
+		cpumask = pinst->cpumask.cbcpu;
+	else
+		cpumask = pinst->cpumask.pcpu;
+
+	len = snprintf(buf, PAGE_SIZE, "%*pb\n",
+		       nr_cpu_ids, cpumask_bits(cpumask));
+	mutex_unlock(&pinst->lock);
+	return len < PAGE_SIZE ? len : -EINVAL;
+}
+
+static ssize_t store_cpumask(struct padata_instance *pinst,
+			     struct attribute *attr,
+			     const char *buf, size_t count)
+{
+	cpumask_var_t new_cpumask;
+	ssize_t ret;
+	int mask_type;
+
+	if (!alloc_cpumask_var(&new_cpumask, GFP_KERNEL))
+		return -ENOMEM;
+
+	ret = bitmap_parse(buf, count, cpumask_bits(new_cpumask),
+			   nr_cpumask_bits);
+	if (ret < 0)
+		goto out;
+
+	mask_type = !strcmp(attr->name, "serial_cpumask") ?
+		PADATA_CPU_SERIAL : PADATA_CPU_PARALLEL;
+	ret = padata_set_cpumask(pinst, mask_type, new_cpumask);
+	if (!ret)
+		ret = count;
+
+out:
+	free_cpumask_var(new_cpumask);
+	return ret;
+}
+
+#define PADATA_ATTR_RW(_name, _show_name, _store_name)		\
+	static struct padata_sysfs_entry _name##_attr =		\
+		__ATTR(_name, 0644, _show_name, _store_name)
+#define PADATA_ATTR_RO(_name, _show_name)		\
+	static struct padata_sysfs_entry _name##_attr = \
+		__ATTR(_name, 0400, _show_name, NULL)
+
+PADATA_ATTR_RW(serial_cpumask, show_cpumask, store_cpumask);
+PADATA_ATTR_RW(parallel_cpumask, show_cpumask, store_cpumask);
+
+/*
+ * Padata sysfs provides the following objects:
+ * serial_cpumask   [RW] - cpumask for serial workers
+ * parallel_cpumask [RW] - cpumask for parallel workers
+ */
+static struct attribute *padata_default_attrs[] = {
+	&serial_cpumask_attr.attr,
+	&parallel_cpumask_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(padata_default);
+
+static ssize_t padata_sysfs_show(struct kobject *kobj,
+				 struct attribute *attr, char *buf)
+{
+	struct padata_instance *pinst;
+	struct padata_sysfs_entry *pentry;
+	ssize_t ret = -EIO;
+
+	pinst = kobj2pinst(kobj);
+	pentry = attr2pentry(attr);
+	if (pentry->show)
+		ret = pentry->show(pinst, attr, buf);
+
+	return ret;
+}
+
+static ssize_t padata_sysfs_store(struct kobject *kobj, struct attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct padata_instance *pinst;
+	struct padata_sysfs_entry *pentry;
+	ssize_t ret = -EIO;
+
+	pinst = kobj2pinst(kobj);
+	pentry = attr2pentry(attr);
+	if (pentry->show)
+		ret = pentry->store(pinst, attr, buf, count);
+
+	return ret;
+}
+
+static const struct sysfs_ops padata_sysfs_ops = {
+	.show = padata_sysfs_show,
+	.store = padata_sysfs_store,
+};
+
+static const struct kobj_type padata_attr_type = {
+	.sysfs_ops = &padata_sysfs_ops,
+	.default_groups = padata_default_groups,
+	.release = padata_sysfs_release,
+};
+
+/**
+ * padata_alloc - allocate and initialize a padata instance
+ * @name: used to identify the instance
+ *
+ * Return: new instance on success, NULL on error
+ */
+struct padata_instance *padata_alloc(const char *name)
+{
+	struct padata_instance *pinst;
+
+	pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
+	if (!pinst)
+		goto err;
+
+	pinst->parallel_wq = alloc_workqueue("%s_parallel", WQ_UNBOUND, 0,
+					     name);
+	if (!pinst->parallel_wq)
+		goto err_free_inst;
+
+	cpus_read_lock();
+
+	pinst->serial_wq = alloc_workqueue("%s_serial", WQ_MEM_RECLAIM |
+					   WQ_CPU_INTENSIVE, 1, name);
+	if (!pinst->serial_wq)
+		goto err_put_cpus;
+
+	if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
+		goto err_free_serial_wq;
+	if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) {
+		free_cpumask_var(pinst->cpumask.pcpu);
+		goto err_free_serial_wq;
+	}
+
+	INIT_LIST_HEAD(&pinst->pslist);
+
+	cpumask_copy(pinst->cpumask.pcpu, cpu_possible_mask);
+	cpumask_copy(pinst->cpumask.cbcpu, cpu_possible_mask);
+
+	if (padata_setup_cpumasks(pinst))
+		goto err_free_masks;
+
+	__padata_start(pinst);
+
+	kobject_init(&pinst->kobj, &padata_attr_type);
+	mutex_init(&pinst->lock);
+
+#ifdef CONFIG_HOTPLUG_CPU
+	cpuhp_state_add_instance_nocalls_cpuslocked(hp_online,
+						    &pinst->cpu_online_node);
+	cpuhp_state_add_instance_nocalls_cpuslocked(CPUHP_PADATA_DEAD,
+						    &pinst->cpu_dead_node);
+#endif
+
+	cpus_read_unlock();
+
+	return pinst;
+
+err_free_masks:
+	free_cpumask_var(pinst->cpumask.pcpu);
+	free_cpumask_var(pinst->cpumask.cbcpu);
+err_free_serial_wq:
+	destroy_workqueue(pinst->serial_wq);
+err_put_cpus:
+	cpus_read_unlock();
+	destroy_workqueue(pinst->parallel_wq);
+err_free_inst:
+	kfree(pinst);
+err:
+	return NULL;
+}
+EXPORT_SYMBOL(padata_alloc);
+
+/**
+ * padata_free - free a padata instance
+ *
+ * @pinst: padata instance to free
+ */
+void padata_free(struct padata_instance *pinst)
+{
+	kobject_put(&pinst->kobj);
+}
+EXPORT_SYMBOL(padata_free);
+
+/**
+ * padata_alloc_shell - Allocate and initialize padata shell.
+ *
+ * @pinst: Parent padata_instance object.
+ *
+ * Return: new shell on success, NULL on error
+ */
+struct padata_shell *padata_alloc_shell(struct padata_instance *pinst)
+{
+	struct parallel_data *pd;
+	struct padata_shell *ps;
+
+	ps = kzalloc(sizeof(*ps), GFP_KERNEL);
+	if (!ps)
+		goto out;
+
+	ps->pinst = pinst;
+
+	cpus_read_lock();
+	pd = padata_alloc_pd(ps);
+	cpus_read_unlock();
+
+	if (!pd)
+		goto out_free_ps;
+
+	mutex_lock(&pinst->lock);
+	RCU_INIT_POINTER(ps->pd, pd);
+	list_add(&ps->list, &pinst->pslist);
+	mutex_unlock(&pinst->lock);
+
+	return ps;
+
+out_free_ps:
+	kfree(ps);
+out:
+	return NULL;
+}
+EXPORT_SYMBOL(padata_alloc_shell);
+
+/**
+ * padata_free_shell - free a padata shell
+ *
+ * @ps: padata shell to free
+ */
+void padata_free_shell(struct padata_shell *ps)
+{
+	struct parallel_data *pd;
+
+	if (!ps)
+		return;
+
+	mutex_lock(&ps->pinst->lock);
+	list_del(&ps->list);
+	pd = rcu_dereference_protected(ps->pd, 1);
+	if (refcount_dec_and_test(&pd->refcnt))
+		padata_free_pd(pd);
+	mutex_unlock(&ps->pinst->lock);
+
+	kfree(ps);
+}
+EXPORT_SYMBOL(padata_free_shell);
+
+void __init padata_init(void)
+{
+	unsigned int i, possible_cpus;
+#ifdef CONFIG_HOTPLUG_CPU
+	int ret;
+
+	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "padata:online",
+				      padata_cpu_online, NULL);
+	if (ret < 0)
+		goto err;
+	hp_online = ret;
+
+	ret = cpuhp_setup_state_multi(CPUHP_PADATA_DEAD, "padata:dead",
+				      NULL, padata_cpu_dead);
+	if (ret < 0)
+		goto remove_online_state;
+#endif
+
+	possible_cpus = num_possible_cpus();
+	padata_works = kmalloc_array(possible_cpus, sizeof(struct padata_work),
+				     GFP_KERNEL);
+	if (!padata_works)
+		goto remove_dead_state;
+
+	for (i = 0; i < possible_cpus; ++i)
+		list_add(&padata_works[i].pw_list, &padata_free_works);
+
+	return;
+
+remove_dead_state:
+#ifdef CONFIG_HOTPLUG_CPU
+	cpuhp_remove_multi_state(CPUHP_PADATA_DEAD);
+remove_online_state:
+	cpuhp_remove_multi_state(hp_online);
+err:
+#endif
+	pr_warn("padata: initialization failed\n");
+}