From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42994) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1btzHZ-0004ey-CE for qemu-devel@nongnu.org; Tue, 11 Oct 2016 11:47:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1btzHY-0007TU-BY for qemu-devel@nongnu.org; Tue, 11 Oct 2016 11:47:57 -0400 References: <1476031419-6805-1-git-send-email-mark.cave-ayland@ilande.co.uk> <1476031419-6805-2-git-send-email-mark.cave-ayland@ilande.co.uk> <97da94bb-e32c-8d9f-7309-ca4bef4bbe7c@redhat.com> From: John Snow Message-ID: <3fa3f1f8-2b7e-8b1f-1272-ff3b3647e0d3@redhat.com> Date: Tue, 11 Oct 2016 11:47:48 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/2] dma-helpers: explicitly pass alignment into dma-helpers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mark Cave-Ayland , Eric Blake , keith.busch@intel.com, kwolf@redhat.com, mreitz@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org 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 >>> --- >> >>> @@ -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 > > 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