block, cfq: kill ioc_gone
Now that cic's are immediately unlinked under both locks, there's no
need to count and drain cic's before module unload. RCU callback
completion is waited with rcu_barrier().
While at it, remove residual RCU operations on cic_list.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ff44435..ae7791a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -62,10 +62,6 @@
static struct kmem_cache *cfq_pool;
static struct kmem_cache *cfq_ioc_pool;
-static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
-static struct completion *ioc_gone;
-static DEFINE_SPINLOCK(ioc_gone_lock);
-
#define CFQ_PRIO_LISTS IOPRIO_BE_NR
#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
@@ -2671,26 +2667,8 @@
static void cfq_cic_free_rcu(struct rcu_head *head)
{
- struct cfq_io_context *cic;
-
- cic = container_of(head, struct cfq_io_context, rcu_head);
-
- kmem_cache_free(cfq_ioc_pool, cic);
- elv_ioc_count_dec(cfq_ioc_count);
-
- if (ioc_gone) {
- /*
- * CFQ scheduler is exiting, grab exit lock and check
- * the pending io context count. If it hits zero,
- * complete ioc_gone and set it back to NULL
- */
- spin_lock(&ioc_gone_lock);
- if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
- complete(ioc_gone);
- ioc_gone = NULL;
- }
- spin_unlock(&ioc_gone_lock);
- }
+ kmem_cache_free(cfq_ioc_pool,
+ container_of(head, struct cfq_io_context, rcu_head));
}
static void cfq_cic_free(struct cfq_io_context *cic)
@@ -2705,7 +2683,7 @@
BUG_ON(!(dead_key & CIC_DEAD_KEY));
radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
- hlist_del_rcu(&cic->cic_list);
+ hlist_del(&cic->cic_list);
cfq_cic_free(cic);
}
@@ -2782,7 +2760,6 @@
INIT_HLIST_NODE(&cic->cic_list);
cic->exit = cfq_exit_cic;
cic->release = cfq_release_cic;
- elv_ioc_count_inc(cfq_ioc_count);
}
return cic;
@@ -3072,7 +3049,7 @@
ret = radix_tree_insert(&ioc->radix_root, q->id, cic);
if (likely(!ret)) {
- hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
+ hlist_add_head(&cic->cic_list, &ioc->cic_list);
list_add(&cic->queue_list, &cfqd->cic_list);
cic = NULL;
} else if (ret == -EEXIST) {
@@ -4156,19 +4133,9 @@
static void __exit cfq_exit(void)
{
- DECLARE_COMPLETION_ONSTACK(all_gone);
blkio_policy_unregister(&blkio_policy_cfq);
elv_unregister(&iosched_cfq);
- ioc_gone = &all_gone;
- /* ioc_gone's update must be visible before reading ioc_count */
- smp_wmb();
-
- /*
- * this also protects us from entering cfq_slab_kill() with
- * pending RCU callbacks
- */
- if (elv_ioc_count_read(cfq_ioc_count))
- wait_for_completion(&all_gone);
+ rcu_barrier(); /* make sure all cic RCU frees are complete */
cfq_slab_kill();
}