Re: [patch] nbd: blk_mq_init_queue returns an error code on failure, not NULL

[Omar Sandoval]

On Mon, Jan 09, 2017 at 03:20:31PM -0500, Jeff Moyer wrote:
> Additionally, don't assign directly to disk->queue, otherwise
> blk_put_queue (called via put_disk) will choke (panic) on the errno
> stored there.
> 
> Bug found by code inspection after Omar found a similar issue in
> virtio_blk.  Compile-tested only.
> 
> Signed-off-by: Jeff Moyer 

Reviewed-by: Omar Sandoval 

Compile-reviewed only :) Josef can probably test it if he cares enough,
but it looks right.

> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 38c576f..50a2020 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -1042,6 +1042,7 @@ static int __init nbd_init(void)
>   return -ENOMEM;
>  
>   for (i = 0; i < nbds_max; i++) {
> + struct request_queue *q;
>   struct gendisk *disk = alloc_disk(1 << part_shift);
>   if (!disk)
>   goto out;
> @@ -1067,12 +1068,13 @@ static int __init nbd_init(void)
>* every gendisk to have its very own request_queue struct.
>* These structs are big so we dynamically allocate them.
>*/
> - disk->queue = blk_mq_init_queue(_dev[i].tag_set);
> - if (!disk->queue) {
> + q = blk_mq_init_queue(_dev[i].tag_set);
> + if (IS_ERR(q)) {
>   blk_mq_free_tag_set(_dev[i].tag_set);
>   put_disk(disk);
>   goto out;
>   }
> + disk->queue = q;
>  
>   /*
>* Tell the block layer that we are not a rotational device
--
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[patch] nbd: blk_mq_init_queue returns an error code on failure, not NULL

[Jeff Moyer]

Additionally, don't assign directly to disk->queue, otherwise
blk_put_queue (called via put_disk) will choke (panic) on the errno
stored there.

Bug found by code inspection after Omar found a similar issue in
virtio_blk.  Compile-tested only.

Signed-off-by: Jeff Moyer 

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 38c576f..50a2020 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1042,6 +1042,7 @@ static int __init nbd_init(void)
return -ENOMEM;
 
for (i = 0; i < nbds_max; i++) {
+   struct request_queue *q;
struct gendisk *disk = alloc_disk(1 << part_shift);
if (!disk)
goto out;
@@ -1067,12 +1068,13 @@ static int __init nbd_init(void)
 * every gendisk to have its very own request_queue struct.
 * These structs are big so we dynamically allocate them.
 */
-   disk->queue = blk_mq_init_queue(_dev[i].tag_set);
-   if (!disk->queue) {
+   q = blk_mq_init_queue(_dev[i].tag_set);
+   if (IS_ERR(q)) {
blk_mq_free_tag_set(_dev[i].tag_set);
put_disk(disk);
goto out;
}
+   disk->queue = q;
 
/*
 * Tell the block layer that we are not a rotational device
--
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