Re: [Qemu-devel] [PATCH 1/2] dma-helpers: explicitly pass alignment into dma-helpers

[Kevin Wolf <kwolf@redhat.com>]

Am 11.10.2016 um 17:47 hat John Snow geschrieben:
> On 10/10/2016 03:23 PM, Mark Cave-Ayland wrote:
> >On 10/10/16 17:34, Eric Blake wrote:
> >
> >>On 10/09/2016 11:43 AM, Mark Cave-Ayland wrote:
> >>>The hard-coded default alignment is BDRV_SECTOR_SIZE, however this is not
> >>>necessarily the case for all platforms. Use this as the default alignment for
> >>>all current callers.
> >>>
> >>>Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> >>>---
> >>
> >>>@@ -160,8 +161,8 @@ static void dma_blk_cb(void *opaque, int ret)
> >>>         return;
> >>>     }
> >>>
> >>>-    if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
> >>>-        qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
> >>>+    if (dbs->iov.size & (dbs->align - 1)) {
> >>>+        qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & (dbs->align - 1));
> >>
> >>Would it be any smarter to use osdep.h's QEMU_IS_ALIGNED(dbs->iov.size,
> >>dbs->align) and QEMU_ALIGN_DOWN(dbs->iov.size, dbs->align)?
> >>Semantically it is the same, but the macros make it obvious what the
> >>bit-twiddling is doing.
> >>
> >>Unless you think that needs a tweak,
> >>Reviewed-by: Eric Blake <eblake@redhat.com>
> >
> >I can't say I feel too strongly about it since there are plenty of other
> >examples of this style in the codebase, so I'm happy to go with whatever
> >John/Paolo are most happy with.
> >
> >
> >ATB,
> >
> >Mark.
> >
> 
> I can't pretend I am consistent, but when in doubt use the macro.
> Not worth a respin IMO, but I think this falls out of my
> jurisdiction :)
> 
> Acked-by: John Snow <jsnow@redhat.com>

dma-helpers.c is officially unmaintained, and as the other patch is
clearly IDE, I think the series should go through your tree.

Kevin