Re: [PATCH] block: initialize hd_stuct's reference before assigning it

From: Johannes Thumshirn
Date: Fri May 06 2016 - 06:26:39 EST


On Tue, May 03, 2016 at 03:38:03PM +0200, Johannes Thumshirn wrote:
> Inititialize the hd_struct's perpcu reference before assigning the hd_struct
> to the partition table list.
>
> This fixes a race which could be triggered using a simple partition
> creation/deletion loop with virtio-blk on aarch64.
>
> Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
> ---
> block/partition-generic.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/block/partition-generic.c b/block/partition-generic.c
> index 5d87019..aa5b83a 100644
> --- a/block/partition-generic.c
> +++ b/block/partition-generic.c
> @@ -361,6 +361,10 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
> goto out_del;
> }
>
> + err = -ENOMEM;
> + if (hd_ref_init(p))
> + goto out_free_info;
> +
> /* everything is up and running, commence */
> rcu_assign_pointer(ptbl->part[partno], p);
>
> @@ -368,8 +372,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
> if (!dev_get_uevent_suppress(ddev))
> kobject_uevent(&pdev->kobj, KOBJ_ADD);
>
> - if (!hd_ref_init(p))
> - return p;
> + return p;
>
> out_free_info:
> free_part_info(p);
> --
> 1.8.5.2
>

We've just seen that this is already fixed with b30a337ca 'block: partition:
initialize percpuref before sending out KOBJ_ADD'

Sorry for the noise,
Johannes
--
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