1 files changed, 558 insertions, 197 deletions

diff --git a/kernel/padata.c b/kernel/padata.c
index fdd8ae6..7510194 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -26,18 +26,19 @@
 #include <linux/mutex.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/sysfs.h>
 #include <linux/rcupdate.h>
 
-#define MAX_SEQ_NR INT_MAX - NR_CPUS
+#define MAX_SEQ_NR (INT_MAX - NR_CPUS)
 #define MAX_OBJ_NUM 1000
 
 static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
 {
 	int cpu, target_cpu;
 
-	target_cpu = cpumask_first(pd->cpumask);
+	target_cpu = cpumask_first(pd->cpumask.pcpu);
 	for (cpu = 0; cpu < cpu_index; cpu++)
-		target_cpu = cpumask_next(target_cpu, pd->cpumask);
+		target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);
 
 	return target_cpu;
 }
@@ -53,26 +54,27 @@ static int padata_cpu_hash(struct padata_priv *padata)
 	 * Hash the sequence numbers to the cpus by taking
 	 * seq_nr mod. number of cpus in use.
 	 */
-	cpu_index =  padata->seq_nr % cpumask_weight(pd->cpumask);
+	cpu_index =  padata->seq_nr % cpumask_weight(pd->cpumask.pcpu);
 
 	return padata_index_to_cpu(pd, cpu_index);
 }
 
-static void padata_parallel_worker(struct work_struct *work)
+static void padata_parallel_worker(struct work_struct *parallel_work)
 {
-	struct padata_queue *queue;
+	struct padata_parallel_queue *pqueue;
 	struct parallel_data *pd;
 	struct padata_instance *pinst;
 	LIST_HEAD(local_list);
 
 	local_bh_disable();
-	queue = container_of(work, struct padata_queue, pwork);
-	pd = queue->pd;
+	pqueue = container_of(parallel_work,
+			      struct padata_parallel_queue, work);
+	pd = pqueue->pd;
 	pinst = pd->pinst;
 
-	spin_lock(&queue->parallel.lock);
-	list_replace_init(&queue->parallel.list, &local_list);
-	spin_unlock(&queue->parallel.lock);
+	spin_lock(&pqueue->parallel.lock);
+	list_replace_init(&pqueue->parallel.list, &local_list);
+	spin_unlock(&pqueue->parallel.lock);
 
 	while (!list_empty(&local_list)) {
 		struct padata_priv *padata;
@@ -94,7 +96,7 @@ static void padata_parallel_worker(struct work_struct *work)
  * @pinst: padata instance
  * @padata: object to be parallelized
  * @cb_cpu: cpu the serialization callback function will run on,
- *          must be in the cpumask of padata.
+ *          must be in the serial cpumask of padata(i.e. cpumask.cbcpu).
  *
  * The parallelization callback function will run with BHs off.
  * Note: Every object which is parallelized by padata_do_parallel
@@ -104,15 +106,18 @@ int padata_do_parallel(struct padata_instance *pinst,
 		       struct padata_priv *padata, int cb_cpu)
 {
 	int target_cpu, err;
-	struct padata_queue *queue;
+	struct padata_parallel_queue *queue;
 	struct parallel_data *pd;
 
 	rcu_read_lock_bh();
 
 	pd = rcu_dereference(pinst->pd);
 
-	err = 0;
-	if (!(pinst->flags & PADATA_INIT))
+	err = -EINVAL;
+	if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)
+		goto out;
+
+	if (!cpumask_test_cpu(cb_cpu, pd->cpumask.cbcpu))
 		goto out;
 
 	err =  -EBUSY;
@@ -122,11 +127,7 @@ int padata_do_parallel(struct padata_instance *pinst,
 	if (atomic_read(&pd->refcnt) >= MAX_OBJ_NUM)
 		goto out;
 
-	err = -EINVAL;
-	if (!cpumask_test_cpu(cb_cpu, pd->cpumask))
-		goto out;
-
-	err = -EINPROGRESS;
+	err = 0;
 	atomic_inc(&pd->refcnt);
 	padata->pd = pd;
 	padata->cb_cpu = cb_cpu;
@@ -137,13 +138,13 @@ int padata_do_parallel(struct padata_instance *pinst,
 	padata->seq_nr = atomic_inc_return(&pd->seq_nr);
 
 	target_cpu = padata_cpu_hash(padata);
-	queue = per_cpu_ptr(pd->queue, target_cpu);
+	queue = per_cpu_ptr(pd->pqueue, target_cpu);
 
 	spin_lock(&queue->parallel.lock);
 	list_add_tail(&padata->list, &queue->parallel.list);
 	spin_unlock(&queue->parallel.lock);
 
-	queue_work_on(target_cpu, pinst->wq, &queue->pwork);
+	queue_work_on(target_cpu, pinst->wq, &queue->work);
 
 out:
 	rcu_read_unlock_bh();
@@ -171,84 +172,52 @@ EXPORT_SYMBOL(padata_do_parallel);
  */
 static struct padata_priv *padata_get_next(struct parallel_data *pd)
 {
-	int cpu, num_cpus, empty, calc_seq_nr;
-	int seq_nr, next_nr, overrun, next_overrun;
-	struct padata_queue *queue, *next_queue;
+	int cpu, num_cpus;
+	int next_nr, next_index;
+	struct padata_parallel_queue *queue, *next_queue;
 	struct padata_priv *padata;
 	struct padata_list *reorder;
 
-	empty = 0;
-	next_nr = -1;
-	next_overrun = 0;
-	next_queue = NULL;
-
-	num_cpus = cpumask_weight(pd->cpumask);
-
-	for_each_cpu(cpu, pd->cpumask) {
-		queue = per_cpu_ptr(pd->queue, cpu);
-		reorder = &queue->reorder;
-
-		/*
-		 * Calculate the seq_nr of the object that should be
-		 * next in this reorder queue.
-		 */
-		overrun = 0;
-		calc_seq_nr = (atomic_read(&queue->num_obj) * num_cpus)
-			       + queue->cpu_index;
+	num_cpus = cpumask_weight(pd->cpumask.pcpu);
 
-		if (unlikely(calc_seq_nr > pd->max_seq_nr)) {
-			calc_seq_nr = calc_seq_nr - pd->max_seq_nr - 1;
-			overrun = 1;
-		}
-
-		if (!list_empty(&reorder->list)) {
-			padata = list_entry(reorder->list.next,
-					    struct padata_priv, list);
-
-			seq_nr  = padata->seq_nr;
-			BUG_ON(calc_seq_nr != seq_nr);
-		} else {
-			seq_nr = calc_seq_nr;
-			empty++;
-		}
-
-		if (next_nr < 0 || seq_nr < next_nr
-		    || (next_overrun && !overrun)) {
-			next_nr = seq_nr;
-			next_overrun = overrun;
-			next_queue = queue;
-		}
+	/*
+	 * Calculate the percpu reorder queue and the sequence
+	 * number of the next object.
+	 */
+	next_nr = pd->processed;
+	next_index = next_nr % num_cpus;
+	cpu = padata_index_to_cpu(pd, next_index);
+	next_queue = per_cpu_ptr(pd->pqueue, cpu);
+
+	if (unlikely(next_nr > pd->max_seq_nr)) {
+		next_nr = next_nr - pd->max_seq_nr - 1;
+		next_index = next_nr % num_cpus;
+		cpu = padata_index_to_cpu(pd, next_index);
+		next_queue = per_cpu_ptr(pd->pqueue, cpu);
+		pd->processed = 0;
 	}
 
 	padata = NULL;
 
-	if (empty == num_cpus)
-		goto out;
-
 	reorder = &next_queue->reorder;
 
 	if (!list_empty(&reorder->list)) {
 		padata = list_entry(reorder->list.next,
 				    struct padata_priv, list);
 
-		if (unlikely(next_overrun)) {
-			for_each_cpu(cpu, pd->cpumask) {
-				queue = per_cpu_ptr(pd->queue, cpu);
-				atomic_set(&queue->num_obj, 0);
-			}
-		}
+		BUG_ON(next_nr != padata->seq_nr);
 
 		spin_lock(&reorder->lock);
 		list_del_init(&padata->list);
 		atomic_dec(&pd->reorder_objects);
 		spin_unlock(&reorder->lock);
 
-		atomic_inc(&next_queue->num_obj);
+		pd->processed++;
 
 		goto out;
 	}
 
-	queue = per_cpu_ptr(pd->queue, smp_processor_id());
+	queue = per_cpu_ptr(pd->pqueue, smp_processor_id());
 	if (queue->cpu_index == next_queue->cpu_index) {
 		padata = ERR_PTR(-ENODATA);
 		goto out;
@@ -262,7 +231,7 @@ out:
 static void padata_reorder(struct parallel_data *pd)
 {
 	struct padata_priv *padata;
-	struct padata_queue *queue;
+	struct padata_serial_queue *squeue;
 	struct padata_instance *pinst = pd->pinst;
 
 	/*
@@ -301,13 +270,13 @@ static void padata_reorder(struct parallel_data *pd)
 			return;
 		}
 
-		queue = per_cpu_ptr(pd->queue, padata->cb_cpu);
+		squeue = per_cpu_ptr(pd->squeue, padata->cb_cpu);
 
-		spin_lock(&queue->serial.lock);
-		list_add_tail(&padata->list, &queue->serial.list);
-		spin_unlock(&queue->serial.lock);
+		spin_lock(&squeue->serial.lock);
+		list_add_tail(&padata->list, &squeue->serial.list);
+		spin_unlock(&squeue->serial.lock);
 
-		queue_work_on(padata->cb_cpu, pinst->wq, &queue->swork);
+		queue_work_on(padata->cb_cpu, pinst->wq, &squeue->work);
 	}
 
 	spin_unlock_bh(&pd->lock);
@@ -333,19 +302,19 @@ static void padata_reorder_timer(unsigned long arg)
 	padata_reorder(pd);
 }
 
-static void padata_serial_worker(struct work_struct *work)
+static void padata_serial_worker(struct work_struct *serial_work)
 {
-	struct padata_queue *queue;
+	struct padata_serial_queue *squeue;
 	struct parallel_data *pd;
 	LIST_HEAD(local_list);
 
 	local_bh_disable();
-	queue = container_of(work, struct padata_queue, swork);
-	pd = queue->pd;
+	squeue = container_of(serial_work, struct padata_serial_queue, work);
+	pd = squeue->pd;
 
-	spin_lock(&queue->serial.lock);
-	list_replace_init(&queue->serial.list, &local_list);
-	spin_unlock(&queue->serial.lock);
+	spin_lock(&squeue->serial.lock);
+	list_replace_init(&squeue->serial.list, &local_list);
+	spin_unlock(&squeue->serial.lock);
 
 	while (!list_empty(&local_list)) {
 		struct padata_priv *padata;
@@ -372,18 +341,18 @@ static void padata_serial_worker(struct work_struct *work)
 void padata_do_serial(struct padata_priv *padata)
 {
 	int cpu;
-	struct padata_queue *queue;
+	struct padata_parallel_queue *pqueue;
 	struct parallel_data *pd;
 
 	pd = padata->pd;
 
 	cpu = get_cpu();
-	queue = per_cpu_ptr(pd->queue, cpu);
+	pqueue = per_cpu_ptr(pd->pqueue, cpu);
 
-	spin_lock(&queue->reorder.lock);
+	spin_lock(&pqueue->reorder.lock);
 	atomic_inc(&pd->reorder_objects);
-	list_add_tail(&padata->list, &queue->reorder.list);
-	spin_unlock(&queue->reorder.lock);
+	list_add_tail(&padata->list, &pqueue->reorder.list);
+	spin_unlock(&pqueue->reorder.lock);
 
 	put_cpu();
 
@@ -391,52 +360,89 @@ void padata_do_serial(struct padata_priv *padata)
 }
 EXPORT_SYMBOL(padata_do_serial);
 
-/* Allocate and initialize the internal cpumask dependend resources. */
-static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst,
-					     const struct cpumask *cpumask)
+static int padata_setup_cpumasks(struct parallel_data *pd,
+				 const struct cpumask *pcpumask,
+				 const struct cpumask *cbcpumask)
 {
-	int cpu, cpu_index, num_cpus;
-	struct padata_queue *queue;
-	struct parallel_data *pd;
-
-	cpu_index = 0;
+	if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))
+		return -ENOMEM;
 
-	pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
-	if (!pd)
-		goto err;
+	cpumask_and(pd->cpumask.pcpu, pcpumask, cpu_active_mask);
+	if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL)) {
+		free_cpumask_var(pd->cpumask.cbcpu);
+		return -ENOMEM;
+	}
 
-	pd->queue = alloc_percpu(struct padata_queue);
-	if (!pd->queue)
-		goto err_free_pd;
+	cpumask_and(pd->cpumask.cbcpu, cbcpumask, cpu_active_mask);
+	return 0;
+}
 
-	if (!alloc_cpumask_var(&pd->cpumask, GFP_KERNEL))
-		goto err_free_queue;
+static void __padata_list_init(struct padata_list *pd_list)
+{
+	INIT_LIST_HEAD(&pd_list->list);
+	spin_lock_init(&pd_list->lock);
+}
 
-	cpumask_and(pd->cpumask, cpumask, cpu_active_mask);
+/* 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) {
-		queue = per_cpu_ptr(pd->queue, cpu);
+	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);
+	}
+}
 
-		queue->pd = pd;
+/* Initialize all percpu queues used by parallel workers */
+static void padata_init_pqueues(struct parallel_data *pd)
+{
+	int cpu_index, num_cpus, cpu;
+	struct padata_parallel_queue *pqueue;
 
-		queue->cpu_index = cpu_index;
+	cpu_index = 0;
+	for_each_cpu(cpu, pd->cpumask.pcpu) {
+		pqueue = per_cpu_ptr(pd->pqueue, cpu);
+		pqueue->pd = pd;
+		pqueue->cpu_index = cpu_index;
 		cpu_index++;
 
-		INIT_LIST_HEAD(&queue->reorder.list);
-		INIT_LIST_HEAD(&queue->parallel.list);
-		INIT_LIST_HEAD(&queue->serial.list);
-		spin_lock_init(&queue->reorder.lock);
-		spin_lock_init(&queue->parallel.lock);
-		spin_lock_init(&queue->serial.lock);
-
-		INIT_WORK(&queue->pwork, padata_parallel_worker);
-		INIT_WORK(&queue->swork, padata_serial_worker);
-		atomic_set(&queue->num_obj, 0);
+		__padata_list_init(&pqueue->reorder);
+		__padata_list_init(&pqueue->parallel);
+		INIT_WORK(&pqueue->work, padata_parallel_worker);
+		atomic_set(&pqueue->num_obj, 0);
 	}
 
-	num_cpus = cpumask_weight(pd->cpumask);
-	pd->max_seq_nr = (MAX_SEQ_NR / num_cpus) * num_cpus - 1;
+	num_cpus = cpumask_weight(pd->cpumask.pcpu);
+	pd->max_seq_nr = num_cpus ? (MAX_SEQ_NR / num_cpus) * num_cpus - 1 : 0;
+}
+
+/* Allocate and initialize the internal cpumask dependend resources. */
+static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst,
+					     const struct cpumask *pcpumask,
+					     const struct cpumask *cbcpumask)
+{
+	struct parallel_data *pd;
 
+	pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);
+	if (!pd)
+		goto err;
+
+	pd->pqueue = alloc_percpu(struct padata_parallel_queue);
+	if (!pd->pqueue)
+		goto err_free_pd;
+
+	pd->squeue = alloc_percpu(struct padata_serial_queue);
+	if (!pd->squeue)
+		goto err_free_pqueue;
+	if (padata_setup_cpumasks(pd, pcpumask, cbcpumask) < 0)
+		goto err_free_squeue;
+
+	padata_init_pqueues(pd);
+	padata_init_squeues(pd);
 	setup_timer(&pd->timer, padata_reorder_timer, (unsigned long)pd);
 	atomic_set(&pd->seq_nr, -1);
 	atomic_set(&pd->reorder_objects, 0);
@@ -446,8 +452,10 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst,
 
 	return pd;
 
-err_free_queue:
-	free_percpu(pd->queue);
+err_free_squeue:
+	free_percpu(pd->squeue);
+err_free_pqueue:
+	free_percpu(pd->pqueue);
 err_free_pd:
 	kfree(pd);
 err:
@@ -456,8 +464,10 @@ err:
 
 static void padata_free_pd(struct parallel_data *pd)
 {
-	free_cpumask_var(pd->cpumask);
-	free_percpu(pd->queue);
+	free_cpumask_var(pd->cpumask.pcpu);
+	free_cpumask_var(pd->cpumask.cbcpu);
+	free_percpu(pd->pqueue);
+	free_percpu(pd->squeue);
 	kfree(pd);
 }
 
@@ -465,11 +475,12 @@ static void padata_free_pd(struct parallel_data *pd)
 static void padata_flush_queues(struct parallel_data *pd)
 {
 	int cpu;
-	struct padata_queue *queue;
+	struct padata_parallel_queue *pqueue;
+	struct padata_serial_queue *squeue;
 
-	for_each_cpu(cpu, pd->cpumask) {
-		queue = per_cpu_ptr(pd->queue, cpu);
-		flush_work(&queue->pwork);
+	for_each_cpu(cpu, pd->cpumask.pcpu) {
+		pqueue = per_cpu_ptr(pd->pqueue, cpu);
+		flush_work(&pqueue->work);
 	}
 
 	del_timer_sync(&pd->timer);
@@ -477,19 +488,39 @@ static void padata_flush_queues(struct parallel_data *pd)
 	if (atomic_read(&pd->reorder_objects))
 		padata_reorder(pd);
 
-	for_each_cpu(cpu, pd->cpumask) {
-		queue = per_cpu_ptr(pd->queue, cpu);
-		flush_work(&queue->swork);
+	for_each_cpu(cpu, pd->cpumask.cbcpu) {
+		squeue = per_cpu_ptr(pd->squeue, cpu);
+		flush_work(&squeue->work);
 	}
 
 	BUG_ON(atomic_read(&pd->refcnt) != 0);
 }
 
+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();
+
+	get_online_cpus();
+	padata_flush_queues(pinst->pd);
+	put_online_cpus();
+}
+
 /* Replace the internal control stucture with a new one. */
 static void padata_replace(struct padata_instance *pinst,
 			   struct parallel_data *pd_new)
 {
 	struct parallel_data *pd_old = pinst->pd;
+	int notification_mask = 0;
 
 	pinst->flags |= PADATA_RESET;
 
@@ -497,41 +528,162 @@ static void padata_replace(struct padata_instance *pinst,
 
 	synchronize_rcu();
 
+	if (!cpumask_equal(pd_old->cpumask.pcpu, pd_new->cpumask.pcpu))
+		notification_mask |= PADATA_CPU_PARALLEL;
+	if (!cpumask_equal(pd_old->cpumask.cbcpu, pd_new->cpumask.cbcpu))
+		notification_mask |= PADATA_CPU_SERIAL;
+
 	padata_flush_queues(pd_old);
 	padata_free_pd(pd_old);
 
+	if (notification_mask)
+		blocking_notifier_call_chain(&pinst->cpumask_change_notifier,
+					     notification_mask,
+					     &pd_new->cpumask);
+
 	pinst->flags &= ~PADATA_RESET;
 }
 
 /**
- * padata_set_cpumask - set the cpumask that padata should use
+ * padata_register_cpumask_notifier - Registers a notifier that will be called
+ *                             if either pcpu or cbcpu or both cpumasks change.
  *
- * @pinst: padata instance
- * @cpumask: the cpumask to use
+ * @pinst: A poineter to padata instance
+ * @nblock: A pointer to notifier block.
  */
-int padata_set_cpumask(struct padata_instance *pinst,
-			cpumask_var_t cpumask)
+int padata_register_cpumask_notifier(struct padata_instance *pinst,
+				     struct notifier_block *nblock)
 {
+	return blocking_notifier_chain_register(&pinst->cpumask_change_notifier,
+						nblock);
+}
+EXPORT_SYMBOL(padata_register_cpumask_notifier);
+
+/**
+ * padata_unregister_cpumask_notifier - Unregisters cpumask notifier
+ *        registered earlier  using padata_register_cpumask_notifier
+ *
+ * @pinst: A pointer to data instance.
+ * @nlock: A pointer to notifier block.
+ */
+int padata_unregister_cpumask_notifier(struct padata_instance *pinst,
+				       struct notifier_block *nblock)
+{
+	return blocking_notifier_chain_unregister(
+		&pinst->cpumask_change_notifier,
+		nblock);
+}
+EXPORT_SYMBOL(padata_unregister_cpumask_notifier);
+
+
+/* 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_active_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;
 	struct parallel_data *pd;
-	int err = 0;
+
+	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:
+	pd = padata_alloc_pd(pinst, pcpumask, cbcpumask);
+	if (!pd)
+		return -ENOMEM;
+
+	cpumask_copy(pinst->cpumask.pcpu, pcpumask);
+	cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
+
+	padata_replace(pinst, pd);
+
+	if (valid)
+		__padata_start(pinst);
+
+	return 0;
+}
+
+/**
+ * padata_set_cpumasks - Set both parallel and serial cpumasks. The first
+ *                       one is used by parallel workers and the second one
+ *                       by the wokers doing serialization.
+ *
+ * @pinst: padata instance
+ * @pcpumask: the cpumask to use for parallel workers
+ * @cbcpumask: the cpumsak to use for serial workers
+ */
+int padata_set_cpumasks(struct padata_instance *pinst, cpumask_var_t pcpumask,
+			cpumask_var_t cbcpumask)
+{
+	int err;
 
 	mutex_lock(&pinst->lock);
+	get_online_cpus();
 
+	err = __padata_set_cpumasks(pinst, pcpumask, cbcpumask);
+
+	put_online_cpus();
+	mutex_unlock(&pinst->lock);
+
+	return err;
+
+}
+EXPORT_SYMBOL(padata_set_cpumasks);
+
+/**
+ * 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
+ */
+int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
+		       cpumask_var_t cpumask)
+{
+	struct cpumask *serial_mask, *parallel_mask;
+	int err = -EINVAL;
+
+	mutex_lock(&pinst->lock);
 	get_online_cpus();
 
-	pd = padata_alloc_pd(pinst, cpumask);
-	if (!pd) {
-		err = -ENOMEM;
-		goto out;
+	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;
 	}
 
-	cpumask_copy(pinst->cpumask, cpumask);
-
-	padata_replace(pinst, pd);
+	err =  __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
 
 out:
 	put_online_cpus();
-
 	mutex_unlock(&pinst->lock);
 
 	return err;
@@ -543,30 +695,48 @@ static int __padata_add_cpu(struct padata_instance *pinst, int cpu)
 	struct parallel_data *pd;
 
 	if (cpumask_test_cpu(cpu, cpu_active_mask)) {
-		pd = padata_alloc_pd(pinst, pinst->cpumask);
+		pd = padata_alloc_pd(pinst, pinst->cpumask.pcpu,
+				     pinst->cpumask.cbcpu);
 		if (!pd)
 			return -ENOMEM;
 
 		padata_replace(pinst, pd);
+
+		if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) &&
+		    padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
+			__padata_start(pinst);
 	}
 
 	return 0;
 }
 
-/**
- * padata_add_cpu - add a cpu to the padata cpumask
+ /**
+ * padata_add_cpu - add a cpu to one or both(parallel and serial)
+ *                  padata cpumasks.
  *
  * @pinst: padata instance
  * @cpu: cpu to add
+ * @mask: bitmask of flags specifying to which cpumask @cpu shuld be added.
+ *        The @mask may be any combination of the following flags:
+ *          PADATA_CPU_SERIAL   - serial cpumask
+ *          PADATA_CPU_PARALLEL - parallel cpumask
  */
-int padata_add_cpu(struct padata_instance *pinst, int cpu)
+
+int padata_add_cpu(struct padata_instance *pinst, int cpu, int mask)
 {
 	int err;
 
+	if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
+		return -EINVAL;
+
 	mutex_lock(&pinst->lock);
 
 	get_online_cpus();
-	cpumask_set_cpu(cpu, pinst->cpumask);
+	if (mask & PADATA_CPU_SERIAL)
+		cpumask_set_cpu(cpu, pinst->cpumask.cbcpu);
+	if (mask & PADATA_CPU_PARALLEL)
+		cpumask_set_cpu(cpu, pinst->cpumask.pcpu);
+
 	err = __padata_add_cpu(pinst, cpu);
 	put_online_cpus();
 
@@ -578,10 +748,16 @@ EXPORT_SYMBOL(padata_add_cpu);
 
 static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
 {
-	struct parallel_data *pd;
+	struct parallel_data *pd = NULL;
 
 	if (cpumask_test_cpu(cpu, cpu_online_mask)) {
-		pd = padata_alloc_pd(pinst, pinst->cpumask);
+
+		if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) ||
+		    !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))
+			__padata_stop(pinst);
+
+		pd = padata_alloc_pd(pinst, pinst->cpumask.pcpu,
+				     pinst->cpumask.cbcpu);
 		if (!pd)
 			return -ENOMEM;
 
@@ -591,20 +767,32 @@ static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
 	return 0;
 }
 
-/**
- * padata_remove_cpu - remove a cpu from the padata cpumask
+ /**
+ * padata_remove_cpu - remove a cpu from the one or both(serial and paralell)
+ *                     padata cpumasks.
  *
  * @pinst: padata instance
  * @cpu: cpu to remove
+ * @mask: bitmask specifying from which cpumask @cpu should be removed
+ *        The @mask may be any combination of the following flags:
+ *          PADATA_CPU_SERIAL   - serial cpumask
+ *          PADATA_CPU_PARALLEL - parallel cpumask
  */
-int padata_remove_cpu(struct padata_instance *pinst, int cpu)
+int padata_remove_cpu(struct padata_instance *pinst, int cpu, int mask)
 {
 	int err;
 
+	if (!(mask & (PADATA_CPU_SERIAL | PADATA_CPU_PARALLEL)))
+		return -EINVAL;
+
 	mutex_lock(&pinst->lock);
 
 	get_online_cpus();
-	cpumask_clear_cpu(cpu, pinst->cpumask);
+	if (mask & PADATA_CPU_SERIAL)
+		cpumask_clear_cpu(cpu, pinst->cpumask.cbcpu);
+	if (mask & PADATA_CPU_PARALLEL)
+		cpumask_clear_cpu(cpu, pinst->cpumask.pcpu);
+
 	err = __padata_remove_cpu(pinst, cpu);
 	put_online_cpus();
 
@@ -619,11 +807,20 @@ EXPORT_SYMBOL(padata_remove_cpu);
  *
  * @pinst: padata instance to start
  */
-void padata_start(struct padata_instance *pinst)
+int padata_start(struct padata_instance *pinst)
 {
+	int err = 0;
+
 	mutex_lock(&pinst->lock);
-	pinst->flags |= PADATA_INIT;
+
+	if (pinst->flags & PADATA_INVALID)
+		err =-EINVAL;
+
+	 __padata_start(pinst);
+
 	mutex_unlock(&pinst->lock);
+
+	return err;
 }
 EXPORT_SYMBOL(padata_start);
 
@@ -635,12 +832,20 @@ EXPORT_SYMBOL(padata_start);
 void padata_stop(struct padata_instance *pinst)
 {
 	mutex_lock(&pinst->lock);
-	pinst->flags &= ~PADATA_INIT;
+	__padata_stop(pinst);
 	mutex_unlock(&pinst->lock);
 }
 EXPORT_SYMBOL(padata_stop);
 
 #ifdef CONFIG_HOTPLUG_CPU
+
+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_callback(struct notifier_block *nfb,
 			       unsigned long action, void *hcpu)
 {
@@ -653,7 +858,7 @@ static int padata_cpu_callback(struct notifier_block *nfb,
 	switch (action) {
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
-		if (!cpumask_test_cpu(cpu, pinst->cpumask))
+		if (!pinst_has_cpu(pinst, cpu))
 			break;
 		mutex_lock(&pinst->lock);
 		err = __padata_add_cpu(pinst, cpu);
@@ -664,7 +869,7 @@ static int padata_cpu_callback(struct notifier_block *nfb,
 
 	case CPU_DOWN_PREPARE:
 	case CPU_DOWN_PREPARE_FROZEN:
-		if (!cpumask_test_cpu(cpu, pinst->cpumask))
+		if (!pinst_has_cpu(pinst, cpu))
 			break;
 		mutex_lock(&pinst->lock);
 		err = __padata_remove_cpu(pinst, cpu);
@@ -675,7 +880,7 @@ static int padata_cpu_callback(struct notifier_block *nfb,
 
 	case CPU_UP_CANCELED:
 	case CPU_UP_CANCELED_FROZEN:
-		if (!cpumask_test_cpu(cpu, pinst->cpumask))
+		if (!pinst_has_cpu(pinst, cpu))
 			break;
 		mutex_lock(&pinst->lock);
 		__padata_remove_cpu(pinst, cpu);
@@ -683,7 +888,7 @@ static int padata_cpu_callback(struct notifier_block *nfb,
 
 	case CPU_DOWN_FAILED:
 	case CPU_DOWN_FAILED_FROZEN:
-		if (!cpumask_test_cpu(cpu, pinst->cpumask))
+		if (!pinst_has_cpu(pinst, cpu))
 			break;
 		mutex_lock(&pinst->lock);
 		__padata_add_cpu(pinst, cpu);
@@ -694,36 +899,202 @@ static int padata_cpu_callback(struct notifier_block *nfb,
 }
 #endif
 
+static void __padata_free(struct padata_instance *pinst)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+	unregister_hotcpu_notifier(&pinst->cpu_notifier);
+#endif
+
+	padata_stop(pinst);
+	padata_free_pd(pinst->pd);
+	free_cpumask_var(pinst->cpumask.pcpu);
+	free_cpumask_var(pinst->cpumask.cbcpu);
+	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 = bitmap_scnprintf(buf, PAGE_SIZE, cpumask_bits(cpumask),
+			       nr_cpu_ids);
+	if (PAGE_SIZE - len < 2)
+		len = -EINVAL;
+	else
+		len += sprintf(buf + len, "\n");
+
+	mutex_unlock(&pinst->lock);
+	return len;
+}
+
+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,
+};
+
+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_attrs = padata_default_attrs,
+	.release = padata_sysfs_release,
+};
+
 /**
- * padata_alloc - allocate and initialize a padata instance
+ * padata_alloc_possible - Allocate and initialize padata instance.
+ *                         Use the cpu_possible_mask for serial and
+ *                         parallel workers.
  *
- * @cpumask: cpumask that padata uses for parallelization
  * @wq: workqueue to use for the allocated padata instance
  */
-struct padata_instance *padata_alloc(const struct cpumask *cpumask,
-				     struct workqueue_struct *wq)
+struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq)
+{
+	return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask);
+}
+EXPORT_SYMBOL(padata_alloc_possible);
+
+/**
+ * padata_alloc - allocate and initialize a padata instance and specify
+ *                cpumasks for serial and parallel workers.
+ *
+ * @wq: workqueue to use for the allocated padata instance
+ * @pcpumask: cpumask that will be used for padata parallelization
+ * @cbcpumask: cpumask that will be used for padata serialization
+ */
+struct padata_instance *padata_alloc(struct workqueue_struct *wq,
+				     const struct cpumask *pcpumask,
+				     const struct cpumask *cbcpumask)
 {
 	struct padata_instance *pinst;
-	struct parallel_data *pd;
+	struct parallel_data *pd = NULL;
 
 	pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);
 	if (!pinst)
 		goto err;
 
 	get_online_cpus();
-
-	pd = padata_alloc_pd(pinst, cpumask);
-	if (!pd)
+	if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
 		goto err_free_inst;
+	if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) {
+		free_cpumask_var(pinst->cpumask.pcpu);
+		goto err_free_inst;
+	}
+	if (!padata_validate_cpumask(pinst, pcpumask) ||
+	    !padata_validate_cpumask(pinst, cbcpumask))
+		goto err_free_masks;
 
-	if (!alloc_cpumask_var(&pinst->cpumask, GFP_KERNEL))
-		goto err_free_pd;
+	pd = padata_alloc_pd(pinst, pcpumask, cbcpumask);
+	if (!pd)
+		goto err_free_masks;
 
 	rcu_assign_pointer(pinst->pd, pd);
 
 	pinst->wq = wq;
 
-	cpumask_copy(pinst->cpumask, cpumask);
+	cpumask_copy(pinst->cpumask.pcpu, pcpumask);
+	cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);
 
 	pinst->flags = 0;
 
@@ -735,12 +1106,15 @@ struct padata_instance *padata_alloc(const struct cpumask *cpumask,
 
 	put_online_cpus();
 
+	BLOCKING_INIT_NOTIFIER_HEAD(&pinst->cpumask_change_notifier);
+	kobject_init(&pinst->kobj, &padata_attr_type);
 	mutex_init(&pinst->lock);
 
 	return pinst;
 
-err_free_pd:
-	padata_free_pd(pd);
+err_free_masks:
+	free_cpumask_var(pinst->cpumask.pcpu);
+	free_cpumask_var(pinst->cpumask.cbcpu);
 err_free_inst:
 	kfree(pinst);
 	put_online_cpus();
@@ -756,19 +1130,6 @@ EXPORT_SYMBOL(padata_alloc);
  */
 void padata_free(struct padata_instance *pinst)
 {
-	padata_stop(pinst);
-
-	synchronize_rcu();
-
-#ifdef CONFIG_HOTPLUG_CPU
-	unregister_hotcpu_notifier(&pinst->cpu_notifier);
-#endif
-	get_online_cpus();
-	padata_flush_queues(pinst->pd);
-	put_online_cpus();
-
-	padata_free_pd(pinst->pd);
-	free_cpumask_var(pinst->cpumask);
-	kfree(pinst);
+	kobject_put(&pinst->kobj);
 }
 EXPORT_SYMBOL(padata_free);