On Tue, 2007-05-08 at 09:44 -0400, Mark Lord wrote:
> Ben Collins wrote:
> ..
> > static u64 ata_tf_to_lba48(struct ata_taskfile *tf)
> > {
> > - u64 sectors = 0;
> > + u64 sectors;
> > + u32 high, low;
> >
> > - sectors |= ((u64)(tf->hob_lbah & 0xff)) << 40;
> > - sectors |= ((u64)(tf->hob_lbam & 0xff)) << 32;
> > - sectors |= (tf->hob_lbal & 0xff) << 24;
> > - sectors |= (tf->lbah & 0xff) << 16;
> > - sectors |= (tf->lbam & 0xff) << 8;
> > - sectors |= (tf->lbal & 0xff);
> > + high = (tf->hob_lbah << 16) |
> > + (tf->hob_lbam << 8) |
> > + tf->hob_lbal;
> > + low = (tf->lbah << 16) |
> > + (tf->lbam << 8) |
> > + tf->lbal;
> >
> > - return ++sectors;
> > + sectors = ((u64)high << 24) | low;
> > +
> > + return sectors + 1;
> > }
>
> Ben, I very much prefer the fixed version of this function
> as implemented by the patch above.
>
> But.. is the original code actually broken, or just messy?
Due to the bugs we were seeing, we actually noticed that this function
was having signed extension issues as originally implemented. I didn't
look for the actual bug, but reimplemented it based on code in
ide_disk.c, which resolved the issue.
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