linux-kernel - Re: [External] [PATCH v2 2/6] s390, dcssblk: kaddr and pfn can be NULL to ->direct

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Date:   Mon, 30 Jul 2018 07:14:58 +0200
From:   Martin Schwidefsky <schwidefsky@...ibm.com>
To:     Huaisheng HS1 Ye <yehs1@...ovo.com>
Cc:     "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "heiko.carstens@...ibm.com" <heiko.carstens@...ibm.com>,
        "bart.vanassche@....com" <bart.vanassche@....com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "ross.zwisler@...ux.intel.com" <ross.zwisler@...ux.intel.com>,
        "willy@...radead.org" <willy@...radead.org>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>,
        "dave.jiang@...el.com" <dave.jiang@...el.com>,
        "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "jack@...e.cz" <jack@...e.cz>, "agk@...hat.com" <agk@...hat.com>,
        "snitzer@...hat.com" <snitzer@...hat.com>,
        "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "NingTing Cheng" <chengnt@...ovo.com>,
        "colyli@...e.de" <colyli@...e.de>,
        Huaisheng Ye <yehs2007@...o.com>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>
Subject: Re: [External]  [PATCH v2 2/6] s390, dcssblk: kaddr and pfn can be
 NULL to ->direct_access()

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

> 
> Cheers,
> Huaisheng Ye
> 
> > From: Huaisheng Ye <yehs2007@...o.com>
> > Sent: Thursday, July 26, 2018 12:29 AM
> > 
> > From: Huaisheng Ye <yehs1@...ovo.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@...ovo.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.