Re: [External] [PATCH v2 2/6] s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()

From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Huaisheng HS1 Ye <yehs1@lenovo.com>
Cc: "jack@suse.cz" <jack@suse.cz>,
	"snitzer@redhat.com" <snitzer@redhat.com>,
	"heiko.carstens@de.ibm.com" <heiko.carstens@de.ibm.com>,
	"dm-devel@redhat.com" <dm-devel@redhat.com>,
	"agk@redhat.com" <agk@redhat.com>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
	"willy@infradead.org" <willy@infradead.org>,
	"bart.vanassche@wdc.com" <bart.vanassche@wdc.com>,
	"keescook@chromium.org" <keescook@chromium.org>,
	NingTing Cheng <chengnt@lenovo.com>,
	"colyli@suse.de" <colyli@suse.de>,
	"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [External]  [PATCH v2 2/6] s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
Date: Mon, 30 Jul 2018 07:14:58 +0200	[thread overview]
Message-ID: <20180730071458.42e3c5a1@mschwideX1> (raw)
In-Reply-To: <TY2PR03MB334328133134A67C87E5CC5C92290@TY2PR03MB3343.apcprd03.prod.outlook.com>

On Sat, 28 Jul 2018 04:07:25 +0000
Huaisheng HS1 Ye <yehs1@lenovo.com> wrote:

> May I have your ack's for this patch? The whole series would be applied
> to libnvdimm if it could get your approval.
> And any suggestion is welcome.

Sure, it is just two additional ifs. I did not think that this needed an
ack, but here you go:

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

> 
> Cheers,
> Huaisheng Ye
> 
> > From: Huaisheng Ye <yehs2007@zoho.com>
> > Sent: Thursday, July 26, 2018 12:29 AM
> > 
> > From: Huaisheng Ye <yehs1@lenovo.com>
> > 
> > dcssblk_direct_access() needs to check the validity of pointers kaddr
> > and pfn for NULL assignment. If anyone equals to NULL, it doesn't need
> > to calculate the value.
> > 
> > If either of them is equal to NULL, that is to say callers may
> > have no need for kaddr or pfn, so this patch is prepared for allowing
> > them to pass in NULL instead of having to pass in a pointer or local
> > variable that they then just throw away.
> > 
> > Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
> > ---
> >  drivers/s390/block/dcssblk.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
> > index ed60728..23e526c 100644
> > --- a/drivers/s390/block/dcssblk.c
> > +++ b/drivers/s390/block/dcssblk.c
> > @@ -922,9 +922,11 @@ static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
> >  	unsigned long dev_sz;
> > 
> >  	dev_sz = dev_info->end - dev_info->start + 1;
> > -	*kaddr = (void *) dev_info->start + offset;
> > -	*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
> > -			PFN_DEV|PFN_SPECIAL);
> > +	if (kaddr)
> > +		*kaddr = (void *) dev_info->start + offset;
> > +	if (pfn)
> > +		*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
> > +				PFN_DEV|PFN_SPECIAL);
> > 
> >  	return (dev_sz - offset) / PAGE_SIZE;
> >  }
> > --
> > 1.8.3.1  
> 

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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