diff options
| -rw-r--r-- | include/linux/padata.h | 3 | ||||
| -rw-r--r-- | kernel/padata.c | 118 |
2 files changed, 68 insertions, 53 deletions
diff --git a/include/linux/padata.h b/include/linux/padata.h index e7978f8942ca..43d3fd9d17fc 100644 --- a/include/linux/padata.h +++ b/include/linux/padata.h @@ -35,6 +35,7 @@ struct padata_priv { struct parallel_data *pd; int cb_cpu; int cpu; + unsigned int seq_nr; int info; void (*parallel)(struct padata_priv *padata); void (*serial)(struct padata_priv *padata); @@ -105,6 +106,7 @@ struct padata_cpumask { * @reorder_objects: Number of objects waiting in the reorder queues. * @refcnt: Number of objects holding a reference on this parallel_data. * @max_seq_nr: Maximal used sequence number. + * @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. @@ -117,6 +119,7 @@ struct parallel_data { atomic_t reorder_objects; atomic_t refcnt; atomic_t seq_nr; + unsigned int processed; int cpu; struct padata_cpumask cpumask; struct work_struct reorder_work; diff --git a/kernel/padata.c b/kernel/padata.c index 669f5d53d357..832224dcf2e1 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -46,18 +46,13 @@ static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index) return target_cpu; } -static int padata_cpu_hash(struct parallel_data *pd) +static int padata_cpu_hash(struct parallel_data *pd, unsigned int seq_nr) { - unsigned int seq_nr; - int cpu_index; - /* * Hash the sequence numbers to the cpus by taking * seq_nr mod. number of cpus in use. */ - - seq_nr = atomic_inc_return(&pd->seq_nr); - cpu_index = seq_nr % cpumask_weight(pd->cpumask.pcpu); + int cpu_index = seq_nr % cpumask_weight(pd->cpumask.pcpu); return padata_index_to_cpu(pd, cpu_index); } @@ -144,7 +139,8 @@ int padata_do_parallel(struct padata_instance *pinst, padata->pd = pd; padata->cb_cpu = *cb_cpu; - target_cpu = padata_cpu_hash(pd); + padata->seq_nr = atomic_inc_return(&pd->seq_nr); + target_cpu = padata_cpu_hash(pd, padata->seq_nr); padata->cpu = target_cpu; queue = per_cpu_ptr(pd->pqueue, target_cpu); @@ -152,7 +148,7 @@ int padata_do_parallel(struct padata_instance *pinst, list_add_tail(&padata->list, &queue->parallel.list); spin_unlock(&queue->parallel.lock); - queue_work_on(target_cpu, pinst->parallel_wq, &queue->work); + queue_work(pinst->parallel_wq, &queue->work); out: rcu_read_unlock_bh(); @@ -162,21 +158,19 @@ out: EXPORT_SYMBOL(padata_do_parallel); /* - * padata_get_next - Get the next object that needs serialization. + * padata_find_next - Find the next object that needs serialization. * * Return values are: * * A pointer to the control struct of the next object that needs * serialization, if present in one of the percpu reorder queues. * - * -EINPROGRESS, if the next object that needs serialization will + * 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. - * - * -ENODATA, if this cpu has to do the parallel processing for - * the next object. */ -static struct padata_priv *padata_get_next(struct parallel_data *pd) +static struct padata_priv *padata_find_next(struct parallel_data *pd, + bool remove_object) { struct padata_parallel_queue *next_queue; struct padata_priv *padata; @@ -187,28 +181,30 @@ static struct padata_priv *padata_get_next(struct parallel_data *pd) reorder = &next_queue->reorder; spin_lock(&reorder->lock); - if (!list_empty(&reorder->list)) { - padata = list_entry(reorder->list.next, - struct padata_priv, list); - - list_del_init(&padata->list); - atomic_dec(&pd->reorder_objects); + if (list_empty(&reorder->list)) { + spin_unlock(&reorder->lock); + return NULL; + } - pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, - false); + 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); - goto out; + return NULL; } - spin_unlock(&reorder->lock); - if (__this_cpu_read(pd->pqueue->cpu_index) == next_queue->cpu_index) { - padata = ERR_PTR(-ENODATA); - goto out; + if (remove_object) { + list_del_init(&padata->list); + atomic_dec(&pd->reorder_objects); + ++pd->processed; + pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false); } - padata = ERR_PTR(-EINPROGRESS); -out: + spin_unlock(&reorder->lock); return padata; } @@ -234,26 +230,16 @@ static void padata_reorder(struct parallel_data *pd) return; while (1) { - padata = padata_get_next(pd); + 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 (PTR_ERR(padata) == -EINPROGRESS) + if (!padata) break; - /* - * This cpu has to do the parallel processing of the next - * object. It's waiting in the cpu's parallelization queue, - * so exit immediately. - */ - if (PTR_ERR(padata) == -ENODATA) { - spin_unlock_bh(&pd->lock); - return; - } - cb_cpu = padata->cb_cpu; squeue = per_cpu_ptr(pd->squeue, cb_cpu); @@ -277,7 +263,8 @@ static void padata_reorder(struct parallel_data *pd) smp_mb(); next_queue = per_cpu_ptr(pd->pqueue, pd->cpu); - if (!list_empty(&next_queue->reorder.list)) + if (!list_empty(&next_queue->reorder.list) && + padata_find_next(pd, false)) queue_work(pinst->serial_wq, &pd->reorder_work); } @@ -332,9 +319,14 @@ void padata_do_serial(struct padata_priv *padata) struct parallel_data *pd = padata->pd; struct padata_parallel_queue *pqueue = per_cpu_ptr(pd->pqueue, padata->cpu); + struct padata_priv *cur; spin_lock(&pqueue->reorder.lock); - list_add_tail(&padata->list, &pqueue->reorder.list); + /* Sort in ascending order of sequence number. */ + list_for_each_entry_reverse(cur, &pqueue->reorder.list, list) + if (cur->seq_nr < padata->seq_nr) + break; + list_add(&padata->list, &cur->list); atomic_inc(&pd->reorder_objects); spin_unlock(&pqueue->reorder.lock); @@ -353,17 +345,36 @@ static int padata_setup_cpumasks(struct parallel_data *pd, const struct cpumask *pcpumask, const struct cpumask *cbcpumask) { - if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL)) - return -ENOMEM; + struct workqueue_attrs *attrs; + int err = -ENOMEM; + if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL)) + goto out; cpumask_and(pd->cpumask.pcpu, pcpumask, cpu_online_mask); - if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL)) { - free_cpumask_var(pd->cpumask.pcpu); - return -ENOMEM; - } + if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL)) + goto free_pcpu_mask; cpumask_and(pd->cpumask.cbcpu, cbcpumask, cpu_online_mask); + + attrs = alloc_workqueue_attrs(); + if (!attrs) + goto free_cbcpu_mask; + + /* Restrict parallel_wq workers to pd->cpumask.pcpu. */ + cpumask_copy(attrs->cpumask, pd->cpumask.pcpu); + err = apply_workqueue_attrs(pd->pinst->parallel_wq, attrs); + free_workqueue_attrs(attrs); + if (err < 0) + goto free_cbcpu_mask; + return 0; + +free_cbcpu_mask: + free_cpumask_var(pd->cpumask.cbcpu); +free_pcpu_mask: + free_cpumask_var(pd->cpumask.pcpu); +out: + return err; } static void __padata_list_init(struct padata_list *pd_list) @@ -429,6 +440,8 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst, pd->squeue = alloc_percpu(struct padata_serial_queue); if (!pd->squeue) goto err_free_pqueue; + + pd->pinst = pinst; if (padata_setup_cpumasks(pd, pcpumask, cbcpumask) < 0) goto err_free_squeue; @@ -437,7 +450,6 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst, atomic_set(&pd->seq_nr, -1); atomic_set(&pd->reorder_objects, 0); atomic_set(&pd->refcnt, 0); - pd->pinst = pinst; spin_lock_init(&pd->lock); pd->cpu = cpumask_first(pd->cpumask.pcpu); INIT_WORK(&pd->reorder_work, invoke_padata_reorder); @@ -968,8 +980,8 @@ static struct padata_instance *padata_alloc(const char *name, if (!pinst) goto err; - pinst->parallel_wq = alloc_workqueue("%s_parallel", WQ_MEM_RECLAIM | - WQ_CPU_INTENSIVE, 1, name); + pinst->parallel_wq = alloc_workqueue("%s_parallel", WQ_UNBOUND, 0, + name); if (!pinst->parallel_wq) goto err_free_inst; |