OSCL-LXR linux-6.0.1/​kernel/​padata.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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;
 }
 
 static void padata_work_init(struct padata_work *pw, work_func_t work_fn,
                  void *data, int flags)
 {
     if (flags & PADATA_WORK_ONSTACK)
         INIT_WORK_ONSTACK(&pw->pw_work, work_fn);
     else
         INIT_WORK(&pw->pw_work, work_fn);
     pw->pw_data = data;
 }
 
 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);
 
     rcu_read_unlock_bh();
 
     if (pw) {
         padata_work_init(pw, padata_parallel_worker, padata, 0);
         queue_work(pinst->parallel_wq, &pw->pw_work);
     } else {
         /* Maximum works limit exceeded, run in the current task. */
         padata->parallel(padata);
     }
 
     return 0;
 out:
     rcu_read_unlock_bh();
 
     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;
 
     spin_lock(&reorder->lock);
     /* Sort in ascending order of sequence number. */
     list_for_each_entry_reverse(cur, &reorder->list, list)
         if (cur->seq_nr < padata->seq_nr)
             break;
     list_add(&padata->list, &cur->list);
     spin_unlock(&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 / job->min_chunk, 1ul);
     nworks = min(nworks, job->max_threads);
 
     if (nworks == 1) {
         /* Single thread, no coordination needed, cut to the chase. */
         job->thread_fn(job->start, job->start + job->size, job->fn_arg);
         return;
     }
 
     spin_lock_init(&ps.lock);
     init_completion(&ps.completion);
     ps.job         = job;
     ps.nworks      = padata_work_alloc_mt(nworks, &ps, &works);
     ps.nworks_fini = 0;
 
     /*
      * Chunk size is the amount of work a helper does per call to the
      * thread function.  Load balance large jobs between threads by
      * increasing the number of chunks, guarantee at least the minimum
      * chunk size from the caller, and honor the caller's alignment.
      */
     ps.chunk_size = job->size / (ps.nworks * load_balance_factor);
     ps.chunk_size = max(ps.chunk_size, job->min_chunk);
     ps.chunk_size = roundup(ps.chunk_size, job->align);
 
     list_for_each_entry(pw, &works, pw_list)
         queue_work(system_unbound_wq, &pw->pw_work);
 
     /* Use the current thread, which saves starting a workqueue worker. */
     padata_work_init(&my_work, padata_mt_helper, &ps, PADATA_WORK_ONSTACK);
     padata_mt_helper(&my_work.pw_work);
 
     /* Wait for all the helpers to finish. */
     wait_for_completion(&ps.completion);
 
     destroy_work_on_stack(&my_work.pw_work);
     padata_works_free(&works);
 }
 
 static void __padata_list_init(struct padata_list *pd_list)
 {
     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,
     &parallel_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 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)
 {
     if (!ps)
         return;
 
     mutex_lock(&ps->pinst->lock);
     list_del(&ps->list);
     padata_free_pd(rcu_dereference_protected(ps->pd, 1));
     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");
 }

This page was automatically generated by the 2.1.0 LXR engine. The LXR team