Re: [PATCH v2] xen/blkfront: fix ring info addressing

[JÃrgen GroÃ]

On 05.03.20 13:42, Roger Pau Monnà wrote:
> On Thu, Mar 05, 2020 at 12:40:44PM +0100, Juergen Gross wrote:
> > Commit 0265d6e8ddb890 ("xen/blkfront: limit allocated memory size to
> > actual use case") made struct blkfront_ring_info size dynamic. This is
> > fine when running with only one queue, but with multiple queues the
> > addressing of the single queues has to be adapted as the structs are
> > allocated in an array.
> >
> > Fixes: 0265d6e8ddb890 ("xen/blkfront: limit allocated memory size to actual use case")
> > Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> > V2:
> > - get rid of rinfo_ptr() helper
> > - use proper parenthesis in for_each_rinfo()
> > - rename rinfo parameter of for_each_rinfo()
> > ---
> >   drivers/block/xen-blkfront.c | 79 +++++++++++++++++++++++---------------------
> >   1 file changed, 42 insertions(+), 37 deletions(-)
> >
> > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> > index e2ad6bba2281..8e844da826db 100644
> > --- a/drivers/block/xen-blkfront.c
> > +++ b/drivers/block/xen-blkfront.c
> > @@ -213,6 +213,7 @@ struct blkfront_info
> >   	struct blk_mq_tag_set tag_set;
> >   	struct blkfront_ring_info *rinfo;
> >   	unsigned int nr_rings;
> > +	unsigned int rinfo_size;
> >   	/* Save uncomplete reqs and bios for migration. */
> >   	struct list_head requests;
> >   	struct bio_list bio_list;
> > @@ -259,6 +260,18 @@ static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
> >   static void blkfront_gather_backend_features(struct blkfront_info *info);
> >   static int negotiate_mq(struct blkfront_info *info);
> >   
> > +#define for_each_rinfo(info, ptr, idx)				\
> > +	for ((ptr) = (info)->rinfo, (idx) = 0;			\
> > +	     (idx) < (info)->nr_rings;				\
> > +	     (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
> > +
> > +static struct blkfront_ring_info *get_rinfo(struct blkfront_info *info,
>
> I still think inline should be added here, but I don't have such a
> strong opinion to block the patch on it.

I can add it if you like that better. Won't make much difference in the
end.

> Also, info should be constified AFAICT.

Yes.

> With at least info constified:
>
> Acked-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
>
> Can you queue this through the Xen tree?

Sure.


Juergen