Commit 0b6f93bd authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
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blk-cgroup: improve error unwinding in blkg_alloc 



Unwind only the previous initialization steps that happened in blkg_alloc
using goto based unwinding.  This avoids the need for the !queue special
case in blkg_free and thus ensures that any blkg seens outside of
blkg_alloc is always fully constructed.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-4-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 178fa7d4

block/blk-cgroup.c

+19 −20
Original line number Diff line number Diff line
@@ -128,22 +128,16 @@ static void blkg_free_workfn(struct work_struct *work) 
	 * blkcg_mutex is used to synchronize blkg_free_workfn() and

	 * blkcg_deactivate_policy().

	 */

	if (q)

	mutex_lock(&q->blkcg_mutex);



	for (i = 0; i < BLKCG_MAX_POLS; i++)

		if (blkg->pd[i])

			blkcg_policy[i]->pd_free_fn(blkg->pd[i]);



	if (blkg->parent)

		blkg_put(blkg->parent);



	if (q) {

	list_del_init(&blkg->q_node);

	mutex_unlock(&q->blkcg_mutex);

		blk_put_queue(q);

	}



	blk_put_queue(q);

	free_percpu(blkg->iostat_cpu);

	percpu_ref_exit(&blkg->refcnt);

	kfree(blkg);
@@ -265,16 +259,13 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, 
	blkg = kzalloc_node(sizeof(*blkg), gfp_mask, disk->queue->node);

	if (!blkg)

		return NULL;



	if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask))

		goto err_free;



		goto out_free_blkg;

	blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask);

	if (!blkg->iostat_cpu)

		goto err_free;



		goto out_exit_refcnt;

	if (!blk_get_queue(disk->queue))

		goto err_free;

		goto out_free_iostat;



	blkg->q = disk->queue;

	INIT_LIST_HEAD(&blkg->q_node);
@@ -299,8 +290,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, 
		/* alloc per-policy data and attach it to blkg */

		pd = pol->pd_alloc_fn(gfp_mask, disk->queue, blkcg);

		if (!pd)

			goto err_free;



			goto out_free_pds;

		blkg->pd[i] = pd;

		pd->blkg = blkg;

		pd->plid = i;
@@ -309,8 +299,17 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk, 


	return blkg;



err_free:

	blkg_free(blkg);

out_free_pds:

	while (--i >= 0)

		if (blkg->pd[i])

			blkcg_policy[i]->pd_free_fn(blkg->pd[i]);

	blk_put_queue(disk->queue);

out_free_iostat:

	free_percpu(blkg->iostat_cpu);

out_exit_refcnt:

	percpu_ref_exit(&blkg->refcnt);

out_free_blkg:

	kfree(blkg);

	return NULL;

}