diff options
Diffstat (limited to 'kernel/padata.c')
-rw-r--r-- | kernel/padata.c | 61 |
1 files changed, 26 insertions, 35 deletions
diff --git a/kernel/padata.c b/kernel/padata.c index e4a8f8d9b31a..6939111b3cbe 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -34,6 +34,8 @@ #define MAX_OBJ_NUM 1000 +static void padata_free_pd(struct parallel_data *pd); + static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index) { int cpu, target_cpu; @@ -274,7 +276,12 @@ static void padata_reorder(struct parallel_data *pd) * The next object that needs serialization might have arrived to * the reorder queues in the meantime, we will be called again * from the timer function if no one else cares for it. + * + * Ensure reorder_objects is read after pd->lock is dropped so we see + * an increment from another task in padata_do_serial. Pairs with + * smp_mb__after_atomic in padata_do_serial. */ + smp_mb(); if (atomic_read(&pd->reorder_objects) && !(pinst->flags & PADATA_RESET)) mod_timer(&pd->timer, jiffies + HZ); @@ -296,6 +303,7 @@ 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); @@ -305,6 +313,8 @@ static void padata_serial_worker(struct work_struct *serial_work) list_replace_init(&squeue->serial.list, &local_list); spin_unlock(&squeue->serial.lock); + cnt = 0; + while (!list_empty(&local_list)) { struct padata_priv *padata; @@ -314,9 +324,12 @@ static void padata_serial_worker(struct work_struct *serial_work) list_del_init(&padata->list); padata->serial(padata); - atomic_dec(&pd->refcnt); + cnt++; } local_bh_enable(); + + if (atomic_sub_and_test(cnt, &pd->refcnt)) + padata_free_pd(pd); } /** @@ -343,6 +356,13 @@ void padata_do_serial(struct padata_priv *padata) list_add_tail(&padata->list, &pqueue->reorder.list); spin_unlock(&pqueue->reorder.lock); + /* + * Ensure the atomic_inc of reorder_objects above is ordered correctly + * with the trylock of pd->lock in padata_reorder. Pairs with smp_mb + * in padata_reorder. + */ + smp_mb__after_atomic(); + put_cpu(); padata_reorder(pd); @@ -432,7 +452,7 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst, setup_timer(&pd->timer, padata_reorder_timer, (unsigned long)pd); atomic_set(&pd->seq_nr, -1); atomic_set(&pd->reorder_objects, 0); - atomic_set(&pd->refcnt, 0); + atomic_set(&pd->refcnt, 1); pd->pinst = pinst; spin_lock_init(&pd->lock); @@ -457,31 +477,6 @@ static void padata_free_pd(struct parallel_data *pd) kfree(pd); } -/* Flush all objects out of the padata queues. */ -static void padata_flush_queues(struct parallel_data *pd) -{ - int cpu; - struct padata_parallel_queue *pqueue; - struct padata_serial_queue *squeue; - - for_each_cpu(cpu, pd->cpumask.pcpu) { - pqueue = per_cpu_ptr(pd->pqueue, cpu); - flush_work(&pqueue->work); - } - - del_timer_sync(&pd->timer); - - if (atomic_read(&pd->reorder_objects)) - padata_reorder(pd); - - for_each_cpu(cpu, pd->cpumask.cbcpu) { - squeue = per_cpu_ptr(pd->squeue, cpu); - flush_work(&squeue->work); - } - - BUG_ON(atomic_read(&pd->refcnt) != 0); -} - static void __padata_start(struct padata_instance *pinst) { pinst->flags |= PADATA_INIT; @@ -495,10 +490,6 @@ static void __padata_stop(struct padata_instance *pinst) pinst->flags &= ~PADATA_INIT; synchronize_rcu(); - - get_online_cpus(); - padata_flush_queues(pinst->pd); - put_online_cpus(); } /* Replace the internal control structure with a new one. */ @@ -519,8 +510,8 @@ static void padata_replace(struct padata_instance *pinst, if (!cpumask_equal(pd_old->cpumask.cbcpu, pd_new->cpumask.cbcpu)) notification_mask |= PADATA_CPU_SERIAL; - padata_flush_queues(pd_old); - padata_free_pd(pd_old); + if (atomic_dec_and_test(&pd_old->refcnt)) + padata_free_pd(pd_old); if (notification_mask) blocking_notifier_call_chain(&pinst->cpumask_change_notifier, @@ -623,8 +614,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type, struct cpumask *serial_mask, *parallel_mask; int err = -EINVAL; - mutex_lock(&pinst->lock); get_online_cpus(); + mutex_lock(&pinst->lock); switch (cpumask_type) { case PADATA_CPU_PARALLEL: @@ -642,8 +633,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type, err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask); out: - put_online_cpus(); mutex_unlock(&pinst->lock); + put_online_cpus(); return err; } |