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    SubjectRe: [PATCH 16/22] xen-blkfront: Make use of the new sg_map helper function
    On Tue, Apr 18, 2017 at 02:13:59PM +0000, David Laight wrote:
    > From: Logan Gunthorpe
    > > Sent: 13 April 2017 23:05
    > > Straightforward conversion to the new helper, except due to
    > > the lack of error path, we have to warn if unmapable memory
    > > is ever present in the sgl.

    Interesting that you didn't CC any of the maintainers. Could you
    do that in the future please?

    > >
    > > Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
    > > ---
    > > drivers/block/xen-blkfront.c | 33 +++++++++++++++++++++++++++------
    > > 1 file changed, 27 insertions(+), 6 deletions(-)
    > >
    > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
    > > index 5067a0a..7dcf41d 100644
    > > --- a/drivers/block/xen-blkfront.c
    > > +++ b/drivers/block/xen-blkfront.c
    > > @@ -807,8 +807,19 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
    > > BUG_ON(sg->offset + sg->length > PAGE_SIZE);
    > >
    > > if (setup.need_copy) {
    > > - setup.bvec_off = sg->offset;
    > > - setup.bvec_data = kmap_atomic(sg_page(sg));
    > > + setup.bvec_off = 0;
    > > + setup.bvec_data = sg_map(sg, SG_KMAP_ATOMIC);
    > > + if (IS_ERR(setup.bvec_data)) {
    > > + /*
    > > + * This should really never happen unless
    > > + * the code is changed to use memory that is
    > > + * not mappable in the sg. Seeing there is a
    > > + * questionable error path out of here,
    > > + * we WARN.
    > > + */
    > > + WARN(1, "Non-mappable memory used in sg!");
    > > + return 1;
    > > + }
    > ...
    >
    > Perhaps add a flag to mark failure as 'unexpected' and trace (and panic?)
    > inside sg_map().
    >
    > David
    >
    >
    > _______________________________________________
    > Linux-nvdimm mailing list
    > Linux-nvdimm@lists.01.org
    > https://lists.01.org/mailman/listinfo/linux-nvdimm

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