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Commit 1c605d67 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block 

* 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block:
  [PATCH] cfq: Further rbtree traversal and cfq_exit_queue() race fix
  [PATCH 2/2] cfq: fix cic's rbtree traversal
  [PATCH 1/2] iosched: fix typo and barrier()
parents 6fbe85f9 be3b0753

block/as-iosched.c

+3 −2
Original line number Diff line number Diff line
@@ -1844,9 +1844,10 @@ static void __exit as_exit(void) 
	DECLARE_COMPLETION(all_gone);

	elv_unregister(&iosched_as);

	ioc_gone = &all_gone;

	barrier();

	/* ioc_gone's update must be visible before reading ioc_count */

	smp_wmb();

	if (atomic_read(&ioc_count))

		complete(ioc_gone);

		wait_for_completion(ioc_gone);

	synchronize_rcu();

	kmem_cache_destroy(arq_pool);

}

block/cfq-iosched.c

+40 −13
Original line number Diff line number Diff line
@@ -1472,19 +1472,37 @@ cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, 
	return cfqq;

}



static void

cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)

{

	read_lock(&cfq_exit_lock);

	rb_erase(&cic->rb_node, &ioc->cic_root);

	read_unlock(&cfq_exit_lock);

	kmem_cache_free(cfq_ioc_pool, cic);

	atomic_dec(&ioc_count);

}



static struct cfq_io_context *

cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)

{

	struct rb_node *n = ioc->cic_root.rb_node;

	struct rb_node *n;

	struct cfq_io_context *cic;

	void *key = cfqd;

	void *k, *key = cfqd;



restart:

	n = ioc->cic_root.rb_node;

	while (n) {

		cic = rb_entry(n, struct cfq_io_context, rb_node);

		/* ->key must be copied to avoid race with cfq_exit_queue() */

		k = cic->key;

		if (unlikely(!k)) {

			cfq_drop_dead_cic(ioc, cic);

			goto restart;

		}



		if (key < cic->key)

		if (key < k)

			n = n->rb_left;

		else if (key > cic->key)

		else if (key > k)

			n = n->rb_right;

		else

			return cic;
@@ -1497,29 +1515,37 @@ static inline void 
cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,

	     struct cfq_io_context *cic)

{

	struct rb_node **p = &ioc->cic_root.rb_node;

	struct rb_node *parent = NULL;

	struct rb_node **p;

	struct rb_node *parent;

	struct cfq_io_context *__cic;



	read_lock(&cfq_exit_lock);

	void *k;



	cic->ioc = ioc;

	cic->key = cfqd;



	ioc->set_ioprio = cfq_ioc_set_ioprio;



restart:

	parent = NULL;

	p = &ioc->cic_root.rb_node;

	while (*p) {

		parent = *p;

		__cic = rb_entry(parent, struct cfq_io_context, rb_node);

		/* ->key must be copied to avoid race with cfq_exit_queue() */

		k = __cic->key;

		if (unlikely(!k)) {

			cfq_drop_dead_cic(ioc, cic);

			goto restart;

		}



		if (cic->key < __cic->key)

		if (cic->key < k)

			p = &(*p)->rb_left;

		else if (cic->key > __cic->key)

		else if (cic->key > k)

			p = &(*p)->rb_right;

		else

			BUG();

	}



	read_lock(&cfq_exit_lock);

	rb_link_node(&cic->rb_node, parent, p);

	rb_insert_color(&cic->rb_node, &ioc->cic_root);

	list_add(&cic->queue_list, &cfqd->cic_list);
@@ -2439,9 +2465,10 @@ static void __exit cfq_exit(void) 
	DECLARE_COMPLETION(all_gone);

	elv_unregister(&iosched_cfq);

	ioc_gone = &all_gone;

	barrier();

	/* ioc_gone's update must be visible before reading ioc_count */

	smp_wmb();

	if (atomic_read(&ioc_count))

		complete(ioc_gone);

		wait_for_completion(ioc_gone);

	synchronize_rcu();

	cfq_slab_kill();

}