Initial commit: OpenHarmony-v4.0-ReleaseOpenHarmony-v4.0-Release

1 files changed, 1159 insertions, 0 deletions

diff --git a/kernel/padata.c b/kernel/padata.c
new file mode 100644
index 000000000..11ca3ebd8
--- /dev/null
+++ b/kernel/padata.c
@@ -0,0 +1,1159 @@
+// 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>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#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;
+}
+
+static void 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_weight(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;
+
+        atomic_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 (atomic_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 / job->min_chunk, 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;
+        atomic_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 (atomic_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;
+
+        get_online_cpus();
+        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);
+        put_online_cpus();
+
+        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 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;
+
+        get_online_cpus();
+
+        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
+
+        put_online_cpus();
+
+        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:
+        put_online_cpus();
+        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;
+
+        get_online_cpus();
+        pd = padata_alloc_pd(ps);
+        put_online_cpus();
+
+        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)
+{
+        if (!ps)
+                return;
+
+        mutex_lock(&ps->pinst->lock);
+        list_del(&ps->list);
+        padata_free_pd(rcu_dereference_protected(ps->pd, 1));
+        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");
+}