1 files changed, 280 insertions, 219 deletions

diff --git a/kernel/padata.c b/kernel/padata.c
index 72777c10bb9c..e5819bb8bd1d 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -7,20 +7,11 @@
  * Copyright (C) 2008, 2009 secunet Security Networks AG
  * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.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.
+ * 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>
@@ -31,11 +22,30 @@
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/rcupdate.h>
-#include <linux/module.h>
 
-#define MAX_OBJ_NUM 1000
+#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)
 {
@@ -59,30 +69,82 @@ static int padata_cpu_hash(struct parallel_data *pd, unsigned int seq_nr)
 	return padata_index_to_cpu(pd, cpu_index);
 }
 
-static void padata_parallel_worker(struct work_struct *parallel_work)
+static struct padata_work *padata_work_alloc(void)
 {
-	struct padata_parallel_queue *pqueue;
-	LIST_HEAD(local_list);
+	struct padata_work *pw;
 
-	local_bh_disable();
-	pqueue = container_of(parallel_work,
-			      struct padata_parallel_queue, work);
+	lockdep_assert_held(&padata_works_lock);
 
-	spin_lock(&pqueue->parallel.lock);
-	list_replace_init(&pqueue->parallel.list, &local_list);
-	spin_unlock(&pqueue->parallel.lock);
+	if (list_empty(&padata_free_works))
+		return NULL;	/* No more work items allowed to be queued. */
 
-	while (!list_empty(&local_list)) {
-		struct padata_priv *padata;
+	pw = list_first_entry(&padata_free_works, struct padata_work, pw_list);
+	list_del(&pw->pw_list);
+	return pw;
+}
 
-		padata = list_entry(local_list.next,
-				    struct padata_priv, list);
+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;
+}
 
-		list_del_init(&padata->list);
+static int __init padata_work_alloc_mt(int nworks, void *data,
+				       struct list_head *head)
+{
+	int i;
 
-		padata->parallel(padata);
+	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();
 }
 
@@ -106,9 +168,9 @@ 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, target_cpu, err;
-	struct padata_parallel_queue *queue;
+	int i, cpu, cpu_index, err;
 	struct parallel_data *pd;
+	struct padata_work *pw;
 
 	rcu_read_lock_bh();
 
@@ -119,7 +181,7 @@ int padata_do_parallel(struct padata_shell *ps,
 		goto out;
 
 	if (!cpumask_test_cpu(*cb_cpu, pd->cpumask.cbcpu)) {
-		if (!cpumask_weight(pd->cpumask.cbcpu))
+		if (cpumask_empty(pd->cpumask.cbcpu))
 			goto out;
 
 		/* Select an alternate fallback CPU and notify the caller. */
@@ -136,25 +198,26 @@ int padata_do_parallel(struct padata_shell *ps,
 	if ((pinst->flags & PADATA_RESET))
 		goto out;
 
-	if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
-		goto out;
-
-	err = 0;
-	atomic_inc(&pd->refcnt);
+	refcount_inc(&pd->refcnt);
 	padata->pd = pd;
 	padata->cb_cpu = *cb_cpu;
 
-	padata->seq_nr = atomic_inc_return(&pd->seq_nr);
-	target_cpu = padata_cpu_hash(pd, padata->seq_nr);
-	padata->cpu = target_cpu;
-	queue = per_cpu_ptr(pd->pqueue, target_cpu);
+	spin_lock(&padata_works_lock);
+	padata->seq_nr = ++pd->seq_nr;
+	pw = padata_work_alloc();
+	spin_unlock(&padata_works_lock);
 
-	spin_lock(&queue->parallel.lock);
-	list_add_tail(&padata->list, &queue->parallel.list);
-	spin_unlock(&queue->parallel.lock);
+	rcu_read_unlock_bh();
 
-	queue_work(pinst->parallel_wq, &queue->work);
+	if (pw) {
+		padata_work_init(pw, padata_parallel_worker, padata, 0);
+		queue_work(pinst->parallel_wq, &pw->pw_work);
+	} else {
+		/* Maximum works limit exceeded, run in the current task. */
+		padata->parallel(padata);
+	}
 
+	return 0;
 out:
 	rcu_read_unlock_bh();
 
@@ -175,13 +238,11 @@ EXPORT_SYMBOL(padata_do_parallel);
 static struct padata_priv *padata_find_next(struct parallel_data *pd,
 					    bool remove_object)
 {
-	struct padata_parallel_queue *next_queue;
 	struct padata_priv *padata;
 	struct padata_list *reorder;
 	int cpu = pd->cpu;
 
-	next_queue = per_cpu_ptr(pd->pqueue, cpu);
-	reorder = &next_queue->reorder;
+	reorder = per_cpu_ptr(pd->reorder_list, cpu);
 
 	spin_lock(&reorder->lock);
 	if (list_empty(&reorder->list)) {
@@ -216,7 +277,7 @@ static void padata_reorder(struct parallel_data *pd)
 	int cb_cpu;
 	struct padata_priv *padata;
 	struct padata_serial_queue *squeue;
-	struct padata_parallel_queue *next_queue;
+	struct padata_list *reorder;
 
 	/*
 	 * We need to ensure that only one cpu can work on dequeueing of
@@ -260,13 +321,12 @@ static void padata_reorder(struct parallel_data *pd)
 	 *
 	 * 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__after_atomic in padata_do_serial.
+	 * smp_mb in padata_do_serial.
 	 */
 	smp_mb();
 
-	next_queue = per_cpu_ptr(pd->pqueue, pd->cpu);
-	if (!list_empty(&next_queue->reorder.list) &&
-	    padata_find_next(pd, false))
+	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);
 }
 
@@ -310,7 +370,7 @@ static void padata_serial_worker(struct work_struct *serial_work)
 	}
 	local_bh_enable();
 
-	if (atomic_sub_and_test(cnt, &pd->refcnt))
+	if (refcount_sub_and_test(cnt, &pd->refcnt))
 		padata_free_pd(pd);
 }
 
@@ -325,24 +385,24 @@ static void padata_serial_worker(struct work_struct *serial_work)
 void padata_do_serial(struct padata_priv *padata)
 {
 	struct parallel_data *pd = padata->pd;
-	struct padata_parallel_queue *pqueue = per_cpu_ptr(pd->pqueue,
-							   padata->cpu);
+	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;
 
-	spin_lock(&pqueue->reorder.lock);
+	spin_lock(&reorder->lock);
 	/* Sort in ascending order of sequence number. */
-	list_for_each_entry_reverse(cur, &pqueue->reorder.list, list)
+	list_for_each_entry_reverse(cur, &reorder->list, list)
 		if (cur->seq_nr < padata->seq_nr)
 			break;
 	list_add(&padata->list, &cur->list);
-	spin_unlock(&pqueue->reorder.lock);
+	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__after_atomic();
+	smp_mb();
 
 	padata_reorder(pd);
 }
@@ -365,26 +425,96 @@ static int padata_setup_cpumasks(struct padata_instance *pinst)
 	return err;
 }
 
-static int pd_setup_cpumasks(struct parallel_data *pd,
-			     const struct cpumask *pcpumask,
-			     const struct cpumask *cbcpumask)
+static void __init padata_mt_helper(struct work_struct *w)
 {
-	int err = -ENOMEM;
+	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;
 
-	if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))
-		goto out;
-	if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL))
-		goto free_pcpu_mask;
+	spin_lock(&ps->lock);
 
-	cpumask_copy(pd->cpumask.pcpu, pcpumask);
-	cpumask_copy(pd->cpumask.cbcpu, cbcpumask);
+	while (job->size > 0) {
+		unsigned long start, size, end;
 
-	return 0;
+		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;
 
-free_pcpu_mask:
-	free_cpumask_var(pd->cpumask.pcpu);
-out:
-	return err;
+		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)
@@ -407,19 +537,15 @@ static void padata_init_squeues(struct parallel_data *pd)
 	}
 }
 
-/* Initialize all percpu queues used by parallel workers */
-static void padata_init_pqueues(struct parallel_data *pd)
+/* Initialize per-CPU reorder lists */
+static void padata_init_reorder_list(struct parallel_data *pd)
 {
 	int cpu;
-	struct padata_parallel_queue *pqueue;
+	struct padata_list *list;
 
 	for_each_cpu(cpu, pd->cpumask.pcpu) {
-		pqueue = per_cpu_ptr(pd->pqueue, cpu);
-
-		__padata_list_init(&pqueue->reorder);
-		__padata_list_init(&pqueue->parallel);
-		INIT_WORK(&pqueue->work, padata_parallel_worker);
-		atomic_set(&pqueue->num_obj, 0);
+		list = per_cpu_ptr(pd->reorder_list, cpu);
+		__padata_list_init(list);
 	}
 }
 
@@ -427,43 +553,46 @@ static void padata_init_pqueues(struct parallel_data *pd)
 static struct parallel_data *padata_alloc_pd(struct padata_shell *ps)
 {
 	struct padata_instance *pinst = ps->pinst;
-	const struct cpumask *cbcpumask;
-	const struct cpumask *pcpumask;
 	struct parallel_data *pd;
 
-	cbcpumask = pinst->rcpumask.cbcpu;
-	pcpumask = pinst->rcpumask.pcpu;
-
 	pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
 	if (!pd)
 		goto err;
 
-	pd->pqueue = alloc_percpu(struct padata_parallel_queue);
-	if (!pd->pqueue)
+	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_pqueue;
+		goto err_free_reorder_list;
 
 	pd->ps = ps;
-	if (pd_setup_cpumasks(pd, pcpumask, cbcpumask))
+
+	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_pqueues(pd);
+	padata_init_reorder_list(pd);
 	padata_init_squeues(pd);
-	atomic_set(&pd->seq_nr, -1);
-	atomic_set(&pd->refcnt, 1);
+	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_pqueue:
-	free_percpu(pd->pqueue);
+err_free_reorder_list:
+	free_percpu(pd->reorder_list);
 err_free_pd:
 	kfree(pd);
 err:
@@ -474,7 +603,7 @@ static void padata_free_pd(struct parallel_data *pd)
 {
 	free_cpumask_var(pd->cpumask.pcpu);
 	free_cpumask_var(pd->cpumask.cbcpu);
-	free_percpu(pd->pqueue);
+	free_percpu(pd->reorder_list);
 	free_percpu(pd->squeue);
 	kfree(pd);
 }
@@ -512,16 +641,10 @@ static int padata_replace_one(struct padata_shell *ps)
 static int padata_replace(struct padata_instance *pinst)
 {
 	struct padata_shell *ps;
-	int err;
+	int err = 0;
 
 	pinst->flags |= PADATA_RESET;
 
-	cpumask_and(pinst->rcpumask.pcpu, pinst->cpumask.pcpu,
-		    cpu_online_mask);
-
-	cpumask_and(pinst->rcpumask.cbcpu, pinst->cpumask.cbcpu,
-		    cpu_online_mask);
-
 	list_for_each_entry(ps, &pinst->pslist, list) {
 		err = padata_replace_one(ps);
 		if (err)
@@ -531,7 +654,7 @@ static int padata_replace(struct padata_instance *pinst)
 	synchronize_rcu();
 
 	list_for_each_entry_continue_reverse(ps, &pinst->pslist, list)
-		if (atomic_dec_and_test(&ps->opd->refcnt))
+		if (refcount_dec_and_test(&ps->opd->refcnt))
 			padata_free_pd(ps->opd);
 
 	pinst->flags &= ~PADATA_RESET;
@@ -597,7 +720,7 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
 	struct cpumask *serial_mask, *parallel_mask;
 	int err = -EINVAL;
 
-	get_online_cpus();
+	cpus_read_lock();
 	mutex_lock(&pinst->lock);
 
 	switch (cpumask_type) {
@@ -617,49 +740,12 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
 
 out:
 	mutex_unlock(&pinst->lock);
-	put_online_cpus();
+	cpus_read_unlock();
 
 	return err;
 }
 EXPORT_SYMBOL(padata_set_cpumask);
 
-/**
- * padata_start - start the parallel processing
- *
- * @pinst: padata instance to start
- *
- * Return: 0 on success or negative error code
- */
-int padata_start(struct padata_instance *pinst)
-{
-	int err = 0;
-
-	mutex_lock(&pinst->lock);
-
-	if (pinst->flags & PADATA_INVALID)
-		err = -EINVAL;
-
-	__padata_start(pinst);
-
-	mutex_unlock(&pinst->lock);
-
-	return err;
-}
-EXPORT_SYMBOL(padata_start);
-
-/**
- * padata_stop - stop the parallel processing
- *
- * @pinst: padata instance to stop
- */
-void padata_stop(struct padata_instance *pinst)
-{
-	mutex_lock(&pinst->lock);
-	__padata_stop(pinst);
-	mutex_unlock(&pinst->lock);
-}
-EXPORT_SYMBOL(padata_stop);
-
 #ifdef CONFIG_HOTPLUG_CPU
 
 static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
@@ -703,7 +789,7 @@ 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, node);
+	pinst = hlist_entry_safe(node, struct padata_instance, cpu_online_node);
 	if (!pinst_has_cpu(pinst, cpu))
 		return 0;
 
@@ -718,7 +804,7 @@ 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, node);
+	pinst = hlist_entry_safe(node, struct padata_instance, cpu_dead_node);
 	if (!pinst_has_cpu(pinst, cpu))
 		return 0;
 
@@ -734,15 +820,13 @@ static enum cpuhp_state hp_online;
 static void __padata_free(struct padata_instance *pinst)
 {
 #ifdef CONFIG_HOTPLUG_CPU
-	cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD, &pinst->node);
-	cpuhp_state_remove_instance_nocalls(hp_online, &pinst->node);
+	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));
 
-	padata_stop(pinst);
-	free_cpumask_var(pinst->rcpumask.cbcpu);
-	free_cpumask_var(pinst->rcpumask.pcpu);
 	free_cpumask_var(pinst->cpumask.pcpu);
 	free_cpumask_var(pinst->cpumask.cbcpu);
 	destroy_workqueue(pinst->serial_wq);
@@ -877,18 +961,12 @@ static struct kobj_type padata_attr_type = {
 };
 
 /**
- * padata_alloc - allocate and initialize a padata instance and specify
- *                cpumasks for serial and parallel workers.
- *
+ * padata_alloc - allocate and initialize a padata instance
  * @name: used to identify the instance
- * @pcpumask: cpumask that will be used for padata parallelization
- * @cbcpumask: cpumask that will be used for padata serialization
  *
  * Return: new instance on success, NULL on error
  */
-static struct padata_instance *padata_alloc(const char *name,
-					    const struct cpumask *pcpumask,
-					    const struct cpumask *cbcpumask)
+struct padata_instance *padata_alloc(const char *name)
 {
 	struct padata_instance *pinst;
 
@@ -901,7 +979,7 @@ static struct padata_instance *padata_alloc(const char *name,
 	if (!pinst->parallel_wq)
 		goto err_free_inst;
 
-	get_online_cpus();
+	cpus_read_lock();
 
 	pinst->serial_wq = alloc_workqueue("%s_serial", WQ_MEM_RECLAIM |
 					   WQ_CPU_INTENSIVE, 1, name);
@@ -914,72 +992,45 @@ static struct padata_instance *padata_alloc(const char *name,
 		free_cpumask_var(pinst->cpumask.pcpu);
 		goto err_free_serial_wq;
 	}
-	if (!padata_validate_cpumask(pinst, pcpumask) ||
-	    !padata_validate_cpumask(pinst, cbcpumask))
-		goto err_free_masks;
-
-	if (!alloc_cpumask_var(&pinst->rcpumask.pcpu, GFP_KERNEL))
-		goto err_free_masks;
-	if (!alloc_cpumask_var(&pinst->rcpumask.cbcpu, GFP_KERNEL))
-		goto err_free_rcpumask_pcpu;
 
 	INIT_LIST_HEAD(&pinst->pslist);
 
-	cpumask_copy(pinst->cpumask.pcpu, pcpumask);
-	cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
-	cpumask_and(pinst->rcpumask.pcpu, pcpumask, cpu_online_mask);
-	cpumask_and(pinst->rcpumask.cbcpu, cbcpumask, cpu_online_mask);
+	cpumask_copy(pinst->cpumask.pcpu, cpu_possible_mask);
+	cpumask_copy(pinst->cpumask.cbcpu, cpu_possible_mask);
 
 	if (padata_setup_cpumasks(pinst))
-		goto err_free_rcpumask_cbcpu;
+		goto err_free_masks;
 
-	pinst->flags = 0;
+	__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->node);
+	cpuhp_state_add_instance_nocalls_cpuslocked(hp_online,
+						    &pinst->cpu_online_node);
 	cpuhp_state_add_instance_nocalls_cpuslocked(CPUHP_PADATA_DEAD,
-						    &pinst->node);
+						    &pinst->cpu_dead_node);
 #endif
 
-	put_online_cpus();
+	cpus_read_unlock();
 
 	return pinst;
 
-err_free_rcpumask_cbcpu:
-	free_cpumask_var(pinst->rcpumask.cbcpu);
-err_free_rcpumask_pcpu:
-	free_cpumask_var(pinst->rcpumask.pcpu);
 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();
+	cpus_read_unlock();
 	destroy_workqueue(pinst->parallel_wq);
 err_free_inst:
 	kfree(pinst);
 err:
 	return NULL;
 }
-
-/**
- * padata_alloc_possible - Allocate and initialize padata instance.
- *                         Use the cpu_possible_mask for serial and
- *                         parallel workers.
- *
- * @name: used to identify the instance
- *
- * Return: new instance on success, NULL on error
- */
-struct padata_instance *padata_alloc_possible(const char *name)
-{
-	return padata_alloc(name, cpu_possible_mask, cpu_possible_mask);
-}
-EXPORT_SYMBOL(padata_alloc_possible);
+EXPORT_SYMBOL(padata_alloc);
 
 /**
  * padata_free - free a padata instance
@@ -1010,9 +1061,9 @@ struct padata_shell *padata_alloc_shell(struct padata_instance *pinst)
 
 	ps->pinst = pinst;
 
-	get_online_cpus();
+	cpus_read_lock();
 	pd = padata_alloc_pd(ps);
-	put_online_cpus();
+	cpus_read_unlock();
 
 	if (!pd)
 		goto out_free_ps;
@@ -1038,43 +1089,53 @@ EXPORT_SYMBOL(padata_alloc_shell);
  */
 void padata_free_shell(struct padata_shell *ps)
 {
-	struct padata_instance *pinst = ps->pinst;
+	if (!ps)
+		return;
 
-	mutex_lock(&pinst->lock);
+	mutex_lock(&ps->pinst->lock);
 	list_del(&ps->list);
 	padata_free_pd(rcu_dereference_protected(ps->pd, 1));
-	mutex_unlock(&pinst->lock);
+	mutex_unlock(&ps->pinst->lock);
 
 	kfree(ps);
 }
 EXPORT_SYMBOL(padata_free_shell);
 
-#ifdef CONFIG_HOTPLUG_CPU
-
-static __init int padata_driver_init(void)
+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)
-		return ret;
+		goto err;
 	hp_online = ret;
 
 	ret = cpuhp_setup_state_multi(CPUHP_PADATA_DEAD, "padata:dead",
 				      NULL, padata_cpu_dead);
-	if (ret < 0) {
-		cpuhp_remove_multi_state(hp_online);
-		return ret;
-	}
-	return 0;
-}
-module_init(padata_driver_init);
+	if (ret < 0)
+		goto remove_online_state;
+#endif
 
-static __exit void padata_driver_exit(void)
-{
+	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);
-}
-module_exit(padata_driver_exit);
+err:
 #endif
+	pr_warn("padata: initialization failed\n");
+}