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Commit 0f98c38d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

Pull final block layer fixes from Jens Axboe:
 "Unfortunately the hctx/ctx lifetime fix from last pull had some
  issues.  This pull request contains a revert of the problematic
  commit, and a proper rewrite of it.

  The rewrite has been tested by the users complaining about the
  regression, and it works fine now.  Additionally, I've run testing on
  all the blk-mq use cases for it and it passes.  So we should
  definitely get this into 3.19, to avoid regression for some cases"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: release mq's kobjects in blk_release_queue()
  Revert "blk-mq: fix hctx/ctx kobject use-after-free"
parents 0dc17d14 e09aae7e

block/blk-mq-sysfs.c

+2 −23
Original line number Diff line number Diff line
@@ -15,26 +15,6 @@ 


static void blk_mq_sysfs_release(struct kobject *kobj)

{

	struct request_queue *q;



	q = container_of(kobj, struct request_queue, mq_kobj);

	free_percpu(q->queue_ctx);

}



static void blk_mq_ctx_release(struct kobject *kobj)

{

	struct blk_mq_ctx *ctx;



	ctx = container_of(kobj, struct blk_mq_ctx, kobj);

	kobject_put(&ctx->queue->mq_kobj);

}



static void blk_mq_hctx_release(struct kobject *kobj)

{

	struct blk_mq_hw_ctx *hctx;



	hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj);

	kfree(hctx);

}



struct blk_mq_ctx_sysfs_entry {
@@ -338,13 +318,13 @@ static struct kobj_type blk_mq_ktype = { 
static struct kobj_type blk_mq_ctx_ktype = {

	.sysfs_ops	= &blk_mq_sysfs_ops,

	.default_attrs	= default_ctx_attrs,

	.release	= blk_mq_ctx_release,

	.release	= blk_mq_sysfs_release,

};



static struct kobj_type blk_mq_hw_ktype = {

	.sysfs_ops	= &blk_mq_hw_sysfs_ops,

	.default_attrs	= default_hw_ctx_attrs,

	.release	= blk_mq_hctx_release,

	.release	= blk_mq_sysfs_release,

};



static void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx)
@@ -375,7 +355,6 @@ static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx) 
		return ret;



	hctx_for_each_ctx(hctx, ctx, i) {

		kobject_get(&q->mq_kobj);

		ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);

		if (ret)

			break;

block/blk-mq.c

+21 −2
Original line number Diff line number Diff line
@@ -1867,6 +1867,27 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set, 
	mutex_unlock(&set->tag_list_lock);

}



/*

 * It is the actual release handler for mq, but we do it from

 * request queue's release handler for avoiding use-after-free

 * and headache because q->mq_kobj shouldn't have been introduced,

 * but we can't group ctx/kctx kobj without it.

 */

void blk_mq_release(struct request_queue *q)

{

	struct blk_mq_hw_ctx *hctx;

	unsigned int i;



	/* hctx kobj stays in hctx */

	queue_for_each_hw_ctx(q, hctx, i)

		kfree(hctx);



	kfree(q->queue_hw_ctx);



	/* ctx kobj stays in queue_ctx */

	free_percpu(q->queue_ctx);

}



struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)

{

	struct blk_mq_hw_ctx **hctxs;
@@ -2000,10 +2021,8 @@ void blk_mq_free_queue(struct request_queue *q) 


	percpu_ref_exit(&q->mq_usage_counter);



	kfree(q->queue_hw_ctx);

	kfree(q->mq_map);



	q->queue_hw_ctx = NULL;

	q->mq_map = NULL;



	mutex_lock(&all_q_mutex);

block/blk-mq.h

+2 −0
Original line number Diff line number Diff line
@@ -62,6 +62,8 @@ extern void blk_mq_sysfs_unregister(struct request_queue *q); 


extern void blk_mq_rq_timed_out(struct request *req, bool reserved);



void blk_mq_release(struct request_queue *q);



/*

 * Basic implementation of sparser bitmap, allowing the user to spread

 * the bits over more cachelines.

block/blk-sysfs.c

+2 −0
Original line number Diff line number Diff line
@@ -517,6 +517,8 @@ static void blk_release_queue(struct kobject *kobj) 


	if (!q->mq_ops)

		blk_free_flush_queue(q->fq);

	else

		blk_mq_release(q);



	blk_trace_shutdown(q);