diff options
Diffstat (limited to 'kernel/padata.c')
| -rw-r--r-- | kernel/padata.c | 1158 |
1 files changed, 1158 insertions, 0 deletions
diff --git a/kernel/padata.c b/kernel/padata.c new file mode 100644 index 000000000..179fb1518 --- /dev/null +++ b/kernel/padata.c @@ -0,0 +1,1158 @@ +// 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> + */ + +#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(&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_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); + 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 / 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. + */ + 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; + 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"); +} |