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Subject: Re: [PATCH v1 1/3] scsi: ufs: Let UPIU completion trace print RSP
 UPIU
From:   Bean Huo <huobean@gmail.com>
To:     Bart Van Assche <bvanassche@acm.org>, alim.akhtar@samsung.com,
        avri.altman@wdc.com, asutoshd@codeaurora.org, jejb@linux.ibm.com,
        martin.petersen@oracle.com, stanley.chu@mediatek.com,
        beanhuo@micron.com, tomas.winkler@intel.com, cang@codeaurora.org
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 25 May 2021 21:28:36 +0200
In-Reply-To: <628c0050-e3e2-033c-8a25-6fc04d4d5657@acm.org>
References: <20210523211409.210304-1-huobean@gmail.com>
         <20210523211409.210304-2-huobean@gmail.com>
         <628c0050-e3e2-033c-8a25-6fc04d4d5657@acm.org>
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On Sun, 2021-05-23 at 18:24 -0700, Bart Van Assche wrote:
> On 5/23/21 2:14 PM, Bean Huo wrote:
> 
> > +             rq_rsp = (struct utp_upiu_req *)hba-
> > >lrb[tag].ucd_rsp_ptr;
> 
> 
> So a pointer to a response (hba->lrb[tag].ucd_rsp_ptr) is cast to a
> 
> pointer to a request (struct utp_upiu_req *)? That seems really odd
> to
> 
> me. Please explain.

Bart,

these two structures have the same size, and inside the structures,
the both unions have the same members(not exactly 100% identical). 

struct utp_upiu_rsp {
        struct utp_upiu_header header;
        union {
                struct utp_cmd_rsp sr;
                struct utp_upiu_query qr;
        };
};


struct utp_upiu_req {
        struct utp_upiu_header header;
        union {
                struct utp_upiu_cmd             sc;
                struct utp_upiu_query           qr;
                struct utp_upiu_query           uc;
        };
};

Use one point for response and request both, no problem here. It is
true that looks very ood, and very difficult to read them.

If this is problem, I can change the code, let them more readable.

how do you think?

Bean