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/* SPDX-License-Identifier: GPL-2.0-only */
* padata.h - header for the padata parallelization interface
* Copyright (C) 2008, 2009 secunet Security Networks AG
* Copyright (C) 2008, 2009 Steffen Klassert <>
* Copyright (c) 2020 Oracle and/or its affiliates.
* Author: Daniel Jordan <>
#ifndef PADATA_H
#define PADATA_H
#include <linux/compiler_types.h>
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/kobject.h>
#define PADATA_CPU_SERIAL 0x01
* struct padata_priv - Represents one job
* @list: List entry, to attach to the padata lists.
* @pd: Pointer to the internal control structure.
* @cb_cpu: Callback cpu for serializatioon.
* @seq_nr: Sequence number of the parallelized data object.
* @info: Used to pass information from the parallel to the serial function.
* @parallel: Parallel execution function.
* @serial: Serial complete function.
struct padata_priv {
struct list_head list;
struct parallel_data *pd;
int cb_cpu;
unsigned int seq_nr;
int info;
void (*parallel)(struct padata_priv *padata);
void (*serial)(struct padata_priv *padata);
* struct padata_list - one per work type per CPU
* @list: List head.
* @lock: List lock.
struct padata_list {
struct list_head list;
spinlock_t lock;
* struct padata_serial_queue - The percpu padata serial queue
* @serial: List to wait for serialization after reordering.
* @work: work struct for serialization.
* @pd: Backpointer to the internal control structure.
struct padata_serial_queue {
struct padata_list serial;
struct work_struct work;
struct parallel_data *pd;
* struct padata_parallel_queue - The percpu padata parallel queue
* @reorder: List to wait for reordering after parallel processing.
* @num_obj: Number of objects that are processed by this cpu.
struct padata_parallel_queue {
struct padata_list reorder;
atomic_t num_obj;
* struct padata_cpumask - The cpumasks for the parallel/serial workers
* @pcpu: cpumask for the parallel workers.
* @cbcpu: cpumask for the serial (callback) workers.
struct padata_cpumask {
cpumask_var_t pcpu;
cpumask_var_t cbcpu;
* struct parallel_data - Internal control structure, covers everything
* that depends on the cpumask in use.
* @ps: padata_shell object.
* @pqueue: percpu padata queues used for parallelization.
* @squeue: percpu padata queues used for serialuzation.
* @refcnt: Number of objects holding a reference on this parallel_data.
* @seq_nr: Sequence number of the parallelized data object.
* @processed: Number of already processed objects.
* @cpu: Next CPU to be processed.
* @cpumask: The cpumasks in use for parallel and serial workers.
* @reorder_work: work struct for reordering.
* @lock: Reorder lock.
struct parallel_data {
struct padata_shell *ps;
struct padata_parallel_queue __percpu *pqueue;
struct padata_serial_queue __percpu *squeue;
atomic_t refcnt;
unsigned int seq_nr;
unsigned int processed;
int cpu;
struct padata_cpumask cpumask;
struct work_struct reorder_work;
spinlock_t ____cacheline_aligned lock;
* struct padata_shell - Wrapper around struct parallel_data, its
* purpose is to allow the underlying control structure to be replaced
* on the fly using RCU.
* @pinst: padat instance.
* @pd: Actual parallel_data structure which may be substituted on the fly.
* @opd: Pointer to old pd to be freed by padata_replace.
* @list: List entry in padata_instance list.
struct padata_shell {
struct padata_instance *pinst;
struct parallel_data __rcu *pd;
struct parallel_data *opd;
struct list_head list;
* struct padata_mt_job - represents one multithreaded job
* @thread_fn: Called for each chunk of work that a padata thread does.
* @fn_arg: The thread function argument.
* @start: The start of the job (units are job-specific).
* @size: size of this node's work (units are job-specific).
* @align: Ranges passed to the thread function fall on this boundary, with the
* possible exceptions of the beginning and end of the job.
* @min_chunk: The minimum chunk size in job-specific units. This allows
* the client to communicate the minimum amount of work that's
* appropriate for one worker thread to do at once.
* @max_threads: Max threads to use for the job, actual number may be less
* depending on task size and minimum chunk size.
struct padata_mt_job {
void (*thread_fn)(unsigned long start, unsigned long end, void *arg);
void *fn_arg;
unsigned long start;
unsigned long size;
unsigned long align;
unsigned long min_chunk;
int max_threads;
* struct padata_instance - The overall control structure.
* @cpu_online_node: Linkage for CPU online callback.
* @cpu_dead_node: Linkage for CPU offline callback.
* @parallel_wq: The workqueue used for parallel work.
* @serial_wq: The workqueue used for serial work.
* @pslist: List of padata_shell objects attached to this instance.
* @cpumask: User supplied cpumasks for parallel and serial works.
* @rcpumask: Actual cpumasks based on user cpumask and cpu_online_mask.
* @kobj: padata instance kernel object.
* @lock: padata instance lock.
* @flags: padata flags.
struct padata_instance {
struct hlist_node cpu_online_node;
struct hlist_node cpu_dead_node;
struct workqueue_struct *parallel_wq;
struct workqueue_struct *serial_wq;
struct list_head pslist;
struct padata_cpumask cpumask;
struct padata_cpumask rcpumask;
struct kobject kobj;
struct mutex lock;
u8 flags;
#define PADATA_INIT 1
#define PADATA_RESET 2
extern void __init padata_init(void);
static inline void __init padata_init(void) {}
extern struct padata_instance *padata_alloc_possible(const char *name);
extern void padata_free(struct padata_instance *pinst);
extern struct padata_shell *padata_alloc_shell(struct padata_instance *pinst);
extern void padata_free_shell(struct padata_shell *ps);
extern int padata_do_parallel(struct padata_shell *ps,
struct padata_priv *padata, int *cb_cpu);
extern void padata_do_serial(struct padata_priv *padata);
extern void __init padata_do_multithreaded(struct padata_mt_job *job);
extern int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
cpumask_var_t cpumask);
extern int padata_start(struct padata_instance *pinst);
extern void padata_stop(struct padata_instance *pinst);