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Subject: Re: [PATCH v4 3/4] scsi: ufs: cleanup ufs initialization path
From:   Bean Huo <huobean@gmail.com>
To:     Avri Altman <Avri.Altman@wdc.com>,
        "alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
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        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
        "beanhuo@micron.com" <beanhuo@micron.com>,
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        "tomas.winkler@intel.com" <tomas.winkler@intel.com>,
        "cang@codeaurora.org" <cang@codeaurora.org>
Cc:     "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date:   Sat, 30 May 2020 20:38:24 +0200
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Hi Avri
thanks your review.

On Sat, 2020-05-30 at 06:37 +0000, Avri Altman wrote:
> > -       case QUERY_DESC_IDN_RFU_0:
> > -       case QUERY_DESC_IDN_RFU_1:
> 
> You forgot to check that desc_id < QUERY_DESC_IDN_MAX

I deleted it since I saw the caller has checked this.
I will add back.

>  
> 
> > +       if (desc_id == QUERY_DESC_IDN_RFU_0 || desc_id ==
> > QUERY_DESC_IDN_RFU_1)
> >                 *desc_len = 0;
> > -               break;
> > -       default:
> > -               *desc_len = 0;
> > -               return -EINVAL;
> > -       }
> > -       return 0;
> > +       else
> > +               *desc_len = hba->desc_size[desc_id];
> >  }
> >  EXPORT_SYMBOL(ufshcd_map_desc_id_to_length);
> > 
> > +static void ufshcd_update_desc_length(struct ufs_hba *hba,
> > +                                     enum desc_idn desc_id,
> > +                                     unsigned char desc_len)
> > +{
> > +       if (hba->desc_size[desc_id] == QUERY_DESC_MAX_SIZE &&
> > +           desc_id != QUERY_DESC_IDN_STRING)
> > +               hba->desc_size[desc_id] = desc_len;
> > +}
> > +
> >  /**
> >   * ufshcd_read_desc_param - read the specified descriptor
> > parameter
> >   * @hba: Pointer to adapter instance
> > @@ -3168,16 +3105,11 @@ int ufshcd_read_desc_param(struct ufs_hba
> > *hba,
> >         if (desc_id >= QUERY_DESC_IDN_MAX || !param_size)
> >                 return -EINVAL;
> > 
> > -       /* Get the max length of descriptor from structure filled
> > up at probe
> > -        * time.
> > -        */
> > -       ret = ufshcd_map_desc_id_to_length(hba, desc_id,
> > &buff_len);
> > -
> > -       /* Sanity checks */
> > -       if (ret || !buff_len) {
> > -               dev_err(hba->dev, "%s: Failed to get full
> > descriptor length",
> > -                       __func__);
> > -               return ret;
> > +       /* Get the length of descriptor */
> > +       ufshcd_map_desc_id_to_length(hba, desc_id, &buff_len);
> > +       if (!buff_len) {
> > +               dev_err(hba->dev, "%s: Failed to get desc length",
> > __func__);
> > +               return -EINVAL;
> >         }
> > 
> >         /* Check whether we need temp memory */
> 
> The first time we are reading the descriptor, we no longer can rely
> on its true size.
> So for this check, buff_len is 256 and kmalloc will always happen. 
> Do you think that this check is still relevant?

you are right, I will delete this redundat code.

> 
> /* Check whether we need temp memory */
>         if (param_offset != 0 || param_size < buff_len) {
>                 desc_buf = kmalloc(buff_len, GFP_KERNEL);
>                 if (!desc_buf)
>                         return -ENOMEM;
>         } else {
>                 desc_buf = param_read_buf;
>                 is_kmalloc = false;
>         }
> 
> 
> > @@ -3209,6 +3141,9 @@ int ufshcd_read_desc_param(struct ufs_hba
> > *hba,
> >                 goto out;
> >         }
> > 
> > +       ufshcd_update_desc_length(hba, desc_id,
> > +                                 desc_buf[QUERY_DESC_LENGTH_OFFSET
> > ]);
> > +
> >         /* Check wherher we will not copy more data, than available
> > */
> >         if (is_kmalloc && param_size > buff_len)
> >                 param_size = buff_len;
> 
> And here, we might want to update buff_len to hold the true
> descriptor size,
> Before checking the copy-back buffer.
> 

yes, buff_len should be updated here. will change it.

thanks 
Bean