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