(cc'ing Joseph as he worked on the area recently, hi!)
Hello,
On Sat, Apr 07, 2018 at 12:21:48PM +0200, Alexandru Moise wrote:
> The q->id is used as an index within the blkg_tree radix tree.
>
> If the entry is not released before reclaiming the blk_queue_ida's id
> blkcg_init_queue() within a different driver from which this id
> was originally for can fail due to the entry at that index within
> the radix tree already existing.
>
> Signed-off-by: Alexandru Moise <00moses.alexander00@xxxxxxxxx>
> ---
> v2: Added no-op for !CONFIG_BLK_CGROUP
>
> block/blk-cgroup.c | 2 +-
> block/blk-sysfs.c | 4 ++++
> include/linux/blk-cgroup.h | 3 +++
> 3 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index 1c16694ae145..224e937dbb59 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -369,7 +369,7 @@ static void blkg_destroy(struct blkcg_gq *blkg)
> *
> * Destroy all blkgs associated with @q.
> */
> -static void blkg_destroy_all(struct request_queue *q)
> +void blkg_destroy_all(struct request_queue *q)
> {
> struct blkcg_gq *blkg, *n;
>
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index d00d1b0ec109..a72866458f22 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -816,6 +816,10 @@ static void __blk_release_queue(struct work_struct *work)
> if (q->bio_split)
> bioset_free(q->bio_split);
>
> + spin_lock_irq(q->queue_lock);
> + blkg_destroy_all(q);
> + spin_unlock_irq(q->queue_lock);
> +
> ida_simple_remove(&blk_queue_ida, q->id);
> call_rcu(&q->rcu_head, blk_free_queue_rcu);
But we already do this through calling blkcg_exit_queue() from
__blk_release_queue(). What's missing?
Thanks.
--
tejun
