linux-kernel - Re: [PATCH v3 2/3] scsi: ufs: core: Cleanup ufshcd_slave

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Message-ID: <9868763a-d360-db53-02b9-2d7ab9628d79@acm.org>
Date:   Tue, 18 Oct 2022 11:27:25 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Bean Huo <beanhuo@...pp.de>, alim.akhtar@...sung.com,
        avri.altman@....com, asutoshd@...eaurora.org, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, stanley.chu@...iatek.com,
        beanhuo@...ron.com, tomas.winkler@...el.com, cang@...eaurora.org,
        daejun7.park@...sung.com, huobean@...il.com
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/3] scsi: ufs: core: Cleanup ufshcd_slave_alloc()

On 10/18/22 11:16, Bean Huo wrote:
> +static void ufshcd_lu_init(struct ufs_hba *hba, struct scsi_device *sdev)
> +{
> +	u8 lun_qdepth;
> +	u8 *desc_buf;
> +	int ret;
> +	int len;
> +	u8 lun;
> +
> +	lun_qdepth = hba->nutrs;
> +	lun = ufshcd_scsi_to_upiu_lun(sdev->lun);
> +	len = hba->desc_size[QUERY_DESC_IDN_UNIT];

Isn't the preferred style for kernel code to combine the above 
declarations and assignments (but not memory allocation calls)?

> +	desc_buf = kzalloc(len, GFP_KERNEL);
> +	if (!desc_buf)
> +		goto set_qdepth;
> +
> +	ret = ufshcd_read_unit_desc_param(hba, lun, 0, desc_buf, len);
> +	if (ret < 0) {
> +		if (ret == -EOPNOTSUPP)
> +			/* If LU doesn't support unit descriptor, its queue depth is set to 1 */
> +			lun_qdepth = 1;
> +		kfree(desc_buf);
> +		goto set_qdepth;
> +	}
> +
> +	if (desc_buf[UNIT_DESC_PARAM_LU_Q_DEPTH])
> +		/*
> +		 * In per-LU queueing architecture, bLUQueueDepth will not be 0, then we will
> +		 * use the smaller between UFSHCI CAP.NUTRS and UFS LU bLUQueueDepth
> +		 */
> +		lun_qdepth = min_t(int, desc_buf[UNIT_DESC_PARAM_LU_Q_DEPTH], hba->nutrs);

Should a test be added that verifies that UNIT_DESC_PARAM_LU_Q_DEPTH < len?

Additionally, please use braces ({}) around multi-line if-statement bodies.

> +	/*
> +	 * According to UFS device specification, the write protection mode is only supported by
> +	 * normal LU, not supported by WLUN.
> +	 */
> +	if (hba->dev_info.f_power_on_wp_en && lun < hba->dev_info.max_lu_supported &&
> +	    !hba->dev_info.is_lu_power_on_wp &&
> +	    desc_buf[UNIT_DESC_PARAM_LU_WR_PROTECT] == UFS_LU_POWER_ON_WP)
> +		hba->dev_info.is_lu_power_on_wp = true;

Also here, should the following test be added: 
UNIT_DESC_PARAM_LU_WR_PROTECT < len?

Otherwise this patch looks good to me.

Thanks,

Bart.