linux-kernel - RE: [External] Re: [PATCH 1/3] nvdimm/pmem: check the validity of the pointer pfn

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Date:   Wed, 4 Jul 2018 15:35:08 +0000
From:   Huaisheng HS1 Ye <yehs1@...ovo.com>
To:     Dan Williams <dan.j.williams@...el.com>
CC:     linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jens Axboe <axboe@...nel.dk>,
        Greg KH <gregkh@...uxfoundation.org>,
        Bart Van Assche <bart.vanassche@....com>,
        "Jan Kara" <jack@...e.com>, NingTing Cheng <chengnt@...ovo.com>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Huaisheng Ye <yehs2007@...o.com>
Subject: RE: [External]  Re: [PATCH 1/3] nvdimm/pmem: check the validity of
 the pointer pfn

> From: Dan Williams [mailto:dan.j.williams@...el.com]
> Sent: Wednesday, July 04, 2018 10:40 PM
> On Tue, Jul 3, 2018 at 11:40 PM, Huaisheng Ye <yehs2007@...o.com> wrote:
> > From: Huaisheng Ye <yehs1@...ovo.com>
> >
> > Some functions within fs/dax don't need to get gfn from direct_access.
> > Assigning NULL to gfn of dax_direct_access is more intuitive and simple
> > than offering a useless local variable.
> >
> > So direct_access needs to check validity of the pointer pfn For NULL
> > assignment.
> >
> > Signed-off-by: Huaisheng Ye <yehs1@...ovo.com>
> > ---
> >  drivers/nvdimm/pmem.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> > index 9d71492..018f990 100644
> > --- a/drivers/nvdimm/pmem.c
> > +++ b/drivers/nvdimm/pmem.c
> > @@ -233,7 +233,8 @@ __weak long __pmem_direct_access(struct pmem_device *pmem,
> pgoff_t pgoff,
> >                                         PFN_PHYS(nr_pages))))
> >                 return -EIO;
> >         *kaddr = pmem->virt_addr + offset;
> > -       *pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
> > +       if (pfn)
> > +               *pfn = phys_to_pfn_t(pmem->phys_addr + offset,
> pmem->pfn_flags);
> >
> >         /*
> >          * If badblocks are present, limit known good range to the
> 
> Looks good. You also need to update the unit test infrastructure
> version of this operation in:
> 
>     tools/testing/nvdimm/pmem-dax.c

Yes, you are right.

Cheers,
Huaisheng Ye