Re: [PATCH] scsi: aacraid: Allocate cmd_priv with scsicmd

[John Garry]

On 28/01/2023 18:40, Vegard Nossum wrote:
> aac_priv() uses scsi_cmd_priv() which has the comment:
>
> /*
>   * Return the driver private allocation behind the command.
>   * Only works if cmd_size is set in the host template.
>   */
>
> This is set for this driver:
>
> static struct scsi_host_template aac_driver_template = {
> [...]
>     .cmd_size                       = sizeof(struct aac_cmd_priv),
>
> I looked around to see if there was some kind of "allocate cmd" helper,
> but couldn't find it -- scsi_ioctl_reset() allocates one (together with
> struct request) and there are a few uses of ->cmd_size in
> drivers/scsi/scsi_lib.c but there doesn't seem to be a common code path
> for this.
>
> I guess you could use dev->host->hostt->cmd_size or something, but that
> doesn't seem worth it since this is driver specific and we already know
> what the correct value should be.

How this driver allocates a SCSI cmd in this fashion is not proper, and 
hostt->cmd_size would only apply when the SCSI command is allocated in 
the proper fashion, that being as a request - __scsi_execute() -> 
scsi_alloc_request() being an example.

Hannes did have a conversion for this driver to allocate a request in
https://urldefense.com/v3/__https://lore.kernel.org/linux-scsi/8efc0e24-3000-39d9-7676-e0896145f247@xxxxxxx/__;!!ACWV5N9M2RV99hQ!MealB8BN3q8cxYSaB7yKEbHyDmFTNl0YNVQXpVw8Zd0-iNqQ-k4IFxnqONpixfavb0DqGWnkbDVjBJCE22mYq5Ly8Xs$ 
- hopefully we can progress that work at some stage.

Thanks,
John