Re: [PATCH 1/2] scsi: core: Fix sbitmap depth in scsi_realloc_sdev_budget_map()

[Bart Van Assche <bvanassche@acm.org>]

On 3/15/22 03:39, John Garry wrote:
> In commit edb854a3680b ("scsi: core: Reallocate device's budget map on
> queue depth change"), the sbitmap for the device budget map may be
> reallocated after the slave device depth is configured.
> 
> When the sbitmap is reallocated we use the result from
> scsi_device_max_queue_depth() for the sbitmap size, but don't resize to
> match the actual device queue depth.
> 
> Fix by resizing the sbitmap after reallocating the budget sbitmap.
> 
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
>   drivers/scsi/scsi_scan.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index f4e6c68ac99e..2ef78083f1ef 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -223,6 +223,8 @@ static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
>   	int ret;
>   	struct sbitmap sb_backup;
>   
> +	depth = min_t(unsigned int, depth, scsi_device_max_queue_depth(sdev));
> +
>   	/*
>   	 * realloc if new shift is calculated, which is caused by setting
>   	 * up one new default queue depth after calling ->slave_configure
> @@ -245,6 +247,9 @@ static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
>   				scsi_device_max_queue_depth(sdev),
>   				new_shift, GFP_KERNEL,
>   				sdev->request_queue->node, false, true);
> +	if (!ret)
> +		sbitmap_resize(&sdev->budget_map, depth);

Hmm ... why to call both sbitmap_init_node() and sbitmap_resize() 
instead of combining both calls into a single call with the proper depth?

Thanks,

Bart.