Re: [PATCH V4 05/16] scsi: ipr: use sg helper to operate scatterlist

From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-scsi@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Hannes Reinecke <hare@suse.com>, Jim Gill <jgill@vmware.com>,
	Cathy Avery <cavery@redhat.com>,
	"Ewan D . Milne" <emilne@redhat.com>,
	Brian King <brking@us.ibm.com>,
	James Smart <james.smart@broadcom.com>,
	"Juergen E . Fischer" <fischer@norbit.de>,
	Michael Schmitz <schmitzmic@gmail.com>,
	Finn Thain <fthain@telegraphics.com.au>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	devel@driverdev.osuosl.org, linux-usb@vger.kernel.org,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Benjamin Block <bblock@linux.ibm.com>
Subject: Re: [PATCH V4 05/16] scsi: ipr: use sg helper to operate scatterlist
Date: Mon, 17 Jun 2019 16:50:32 +0800	[thread overview]
Message-ID: <20190617085027.GA31002@ming.t460p> (raw)
In-Reply-To: <20190617082423.GE7455@lst.de>

On Mon, Jun 17, 2019 at 10:24:23AM +0200, Christoph Hellwig wrote:
> > -	for (i = 0; i < (len / bsize_elem); i++, buffer += bsize_elem) {
> > -		struct page *page = sg_page(&scatterlist[i]);
> > +	for (i = 0; i < (len / bsize_elem); i++, sg = sg_next(sg), buffer += bsize_elem) {
> 
> Please split the overly long line.

Fine.

> 
> > +		struct page *page = sg_page(sg);
> >  
> >  		kaddr = kmap(page);
> >  		memcpy(kaddr, buffer, bsize_elem);
> >  		kunmap(page);
> 
> Not new in this patch, but this is buggy as scatterlists could have
> offsets.  This should probably use the scatterlist.c copy helper
> eventually.

This sglist is allocated by driver, see ipr_copy_ucode_buffer(), so
offset for any element is zero.

Thanks,
Ming