Re: [RFC PATCH v2 1/2] scsi: ufs: Add Multi-Circular Queue support

[Bart Van Assche]

On 8/12/22 02:10, Manivannan Sadhasivam wrote:
> On Thu, Aug 11, 2022 at 03:33:03AM -0700, Can Guo wrote:
> > +static unsigned int dev_cmd_queue = 1;
> > +static unsigned int read_queues;
>
> Where is this initialized?

The Linux kernel coding style does not allow to explicitly initialize 
static variables to zero.

> > +
> > +static int rw_queue_count_set(const char *val, const struct kernel_param *kp)
> > +{
> > +	unsigned int n;
> > +	int ret;
> > +
> > +	ret = kstrtouint(val, 10, &n);
> > +	if (ret)
> > +		return ret;
> > +	if (n > num_possible_cpus())
> > +		return -EINVAL;
> > +	return param_set_uint(val, kp);
> > +}
> > +
> > +static const struct kernel_param_ops rw_queue_count_ops = {
> > +	.set = rw_queue_count_set,
> > +	.get = param_get_uint,
> > +};
> > +
> > +static unsigned int rw_queues = 8;
> > +module_param_cb(rw_queues, &rw_queue_count_ops, &rw_queues, 0644);
> > +MODULE_PARM_DESC(rw_queues, "Number of queues used for rw. Default value is 8");
> > +
>
> Using module params is not encouraged these days. So please switch to Kconfig.

Hmm ... I think using CONFIG_* variables is worse than using module 
parameters since modifying CONFIG_* variables requires rebuilding the 
kernel.

> > +struct cq_entry {
> > +	/* DW 0-1 */
> > +	__le32 command_desc_base_addr_lo;
> > +	__le32 command_desc_base_addr_hi;
> > +
> > +	/* DW 2 */
> > +	__le16  response_upiu_length;
> > +	__le16  response_upiu_offset;
> > +
> > +	/* DW 3 */
> > +	__le16  prd_table_length;
> > +	__le16  prd_table_offset;
> > +
> > +	/* DW 4 */
> > +	__le32 status;
> > +
> > +	/* DW 5-7 */
> > +	u32 reserved[3];
> > +};
>
> packed?

Using __packed if it is not necessary is wrong since it makes code slower.

Thanks,

Bart.