linux-kernel - Re: [PATCH v9 2/4] scsi: ufs: Introduce HPB feature

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Message-ID: <963815509.21598920082632.JavaMail.epsvc@epcpadp2>
Date:   Tue, 01 Sep 2020 09:24:29 +0900
From:   Daejun Park <daejun7.park@...sung.com>
To:     Bart Van Assche <bvanassche@....org>,
        Daejun Park <daejun7.park@...sung.com>,
        "avri.altman@....com" <avri.altman@....com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "beanhuo@...ron.com" <beanhuo@...ron.com>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "tomas.winkler@...el.com" <tomas.winkler@...el.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>
CC:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sang-yoon Oh <sangyoon.oh@...sung.com>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        Adel Choi <adel.choi@...sung.com>,
        BoRam Shin <boram.shin@...sung.com>
Subject: Re: [PATCH v9 2/4] scsi: ufs: Introduce HPB feature

Hi, Bart

> > diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> > index 618b253e5ec8..df30622a2b67 100644
> > --- a/drivers/scsi/ufs/ufshcd.h
> > +++ b/drivers/scsi/ufs/ufshcd.h
> > @@ -588,6 +588,24 @@ struct ufs_hba_variant_params {
> >  	u16 hba_enable_delay_us;
> >  	u32 wb_flush_threshold;
> >  };
> > +#ifdef CONFIG_SCSI_UFS_HPB
> > +/**
> > + * struct ufshpb_dev_info - UFSHPB device related info
> > + * @num_lu: the number of user logical unit to check whether all lu finished
> > + *          initialization
> > + * @rgn_size: device reported HPB region size
> > + * @srgn_size: device reported HPB sub-region size
> > + * @slave_conf_cnt: counter to check all lu finished initialization
> > + * @hpb_disabled: flag to check if HPB is disabled
> > + */
> > +struct ufshpb_dev_info {
> > +	int num_lu;
> > +	int rgn_size;
> > +	int srgn_size;
> > +	atomic_t slave_conf_cnt;
> > +	bool hpb_disabled;
> > +};
> > +#endif
> 
> Please insert a blank line above "#ifdef CONFIG_SCSI_UFS_HPB"

OK, I will insert a blank line.
 
> > +/* HPB enabled lu list */
> > +static LIST_HEAD(lh_hpb_lu);
> 
> Is it necessary to maintain this list? Or in other words, is it possible to
> change all list_for_each_entry(hpb, &lh_hpb_lu, list_hpb_lu) calls into
> shost_for_each_device() calls?

OK, I will remove lh_hpb_lu.

> > +/* SYSFS functions */
> > +#define ufshpb_sysfs_attr_show_func(__name)				\
> > +static ssize_t __name##_show(struct device *dev,			\
> > +	struct device_attribute *attr, char *buf)			\
> > +{									\
> > +	struct scsi_device *sdev = to_scsi_device(dev);			\
> > +	struct ufshpb_lu *hpb = sdev->hostdata;				\
> > +	if (!hpb)							\
> > +		return -ENOENT;						\
> > +	return snprintf(buf, PAGE_SIZE, "%d\n",				\
> > +			atomic_read(&hpb->stats.__name));		\
> > +}									\
> > +static DEVICE_ATTR_RO(__name)
> 
> Please leave a blank line after declarations (between the "hpb" declaration
> and "if (!hpb)").

OK, I will add a blank line.

> > +#ifndef CONFIG_SCSI_UFS_HPB
> > +[...]
> > +static struct attribute *hpb_dev_attrs[] = { NULL,};
> > +static struct attribute_group ufs_sysfs_hpb_stat_group = {.attrs = hpb_dev_attrs,};
> > +#else
> > +[...]
> > +extern struct attribute_group ufs_sysfs_hpb_stat_group;
> > +#endif
> 
> Defining static variables or arrays in header files is questionable because
> the definition of these variables will be duplicated in each source file that
> header file is included in. Although the general rule for kernel code is to
> confine #ifdefs to header files, for ufs_sysfs_hpb_stat_group I think that
> it is better to surround its use with #ifndef CONFIG_SCSI_UFS_HPB / #endif
> instead of defining a dummy structure as static variable in a header file if
> HPB support is disabled.

OK, I added #ifdef in ufshcd.c.

static const struct attribute_group *ufshcd_driver_groups[] = {
	&ufs_sysfs_unit_descriptor_group,
	&ufs_sysfs_lun_attributes_group,
#ifdef CONFIG_SCSI_UFS_HPB
	&ufs_sysfs_hpb_stat_group,
#endif
	NULL,
};

Thanks,
Daejun