Re: [RESEND PATCH v3] scsi: Bypass certain SCSI commands on disks with "use_192_bytes_for_3f" attribute

[Bart Van Assche]

On 2/23/25 7:48 PM, WangYuli wrote:
> However, "lshw" disregards the "use_192_bytes_for_3f" attribute and
> transmits data with a length of 0xff bytes via ioctl, which can cause
> some hard drives to hang and become unusable.

lshw is a user space utility. use_192_bytes_for_3f is not exposed to
user space as far as I know. So how can the above statement be correct?

> @@ -1613,6 +1614,17 @@ static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
> +	/*
> +	 * Before we queue this command, check attribute use_192_bytes_for_3f.
> +	 * Because transmits data with a length of 0xff bytes via ioctl may
> +	 * cause some hard drives to hang and become unusable.
> +	 */
> +	if (cmd->cmnd[0] == MODE_SENSE && sdev->use_192_bytes_for_3f &&
> +		cmd->cmnd[2] == 0x3f && cmd->cmnd[4] != 192) {
> +		cmd->result = DID_ABORT << 16;
> +		goto done;
> +	}

From include/scsi/scsi_device.h:

unsigned use_192_bytes_for_3f:1; /* ask for 192 bytes from page 0x3f */

The above code uses use_192_bytes_for_3f for another purpose. Please 
respect the purpose of the use_192_bytes_for_3f bitfield.

Thanks,

Bart.