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

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

[Johannes Thumshirn]

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@suse.de>
---
 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

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

[Hannes Reinecke]

On 05/03/2016 03:38 PM, 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@suse.de>
> ---
>  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);
> 
Suggested-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>

:-)

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

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

[Johannes Thumshirn]

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@suse.de>
> ---
>  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
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850