Messages in this thread | | | Date | Wed, 12 Sep 2018 11:13:50 +0200 | From | Roger Pau Monné <> | Subject | Re: [Xen-devel] [PATCH] drivers/block/xen-blkback/common.h: use DIV_ROUND_UP instead of reimplementing its function |
| |
Adding Julien how did the work to support XEN_PAGE_SIZE != PAGE_SIZE.
On Wed, Sep 12, 2018 at 02:14:26AM -0600, Jan Beulich wrote: > >>> On 12.09.18 at 07:45, <zhongjiang@huawei.com> wrote: > > --- a/drivers/block/xen-blkback/common.h > > +++ b/drivers/block/xen-blkback/common.h > > @@ -65,7 +65,7 @@ > > (XEN_PAGES_PER_INDIRECT_FRAME / XEN_PAGES_PER_SEGMENT) > > > > #define MAX_INDIRECT_PAGES \ > > - ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) > > + DIV_ROUND_UP(MAX_INDIRECT_SEGMENTS, SEGS_PER_INDIRECT_FRAME) > > #define INDIRECT_PAGES(_segs) DIV_ROUND_UP(_segs, XEN_PAGES_PER_INDIRECT_FRAME) > > My first reaction was to suggest > > #define MAX_INDIRECT_PAGES INDIRECT_PAGES(MAX_INDIRECT_SEGMENTS) > > but that wouldn't match what's there currently (note the two different > divisors). I can't really decide whether that's just unfortunate naming > of the two macros, or an actual bug.
I think there's indeed a bug here.
AFAICT, MAX_INDIRECT_PAGES should use XEN_PAGES_PER_INDIRECT_FRAME and then it could be changed as Jan suggested.
Current MAX_INDIRECT_PAGES is misnamed and should instead be MAX_INDIRECT_SEGS (which on x86 is exactly the same because PAGE_SIZE == XEN_PAGE_SIZE).
Roger.
| |