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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: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230203150400.3199230-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2023-02-03 16:03:44 +01:00 committed by Jens Axboe
parent 178fa7d498
commit 0b6f93bdf0
1 changed files with 19 additions and 20 deletions
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33
block/blk-cgroup.c
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@ -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;
}