From: Christoph Hellwig <hch@lst.de>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, gross@suse.com,
xen-devel@lists.xenproject.org, Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 09/11] swiotlb-xen: simplify cache maintainance
Date: Fri, 6 Sep 2019 16:01:23 +0200 [thread overview]
Message-ID: <20190906140123.GA9894@lst.de> (raw)
In-Reply-To: <e4f9b393-2631-57cd-f42f-3581e75ab9a3@oracle.com>
On Fri, Sep 06, 2019 at 09:52:12AM -0400, Boris Ostrovsky wrote:
> We need nop definitions of these two for x86.
>
> Everything builds now but that's probably because the calls are under
> 'if (!dev_is_dma_coherent(dev))' which is always false so compiler
> optimized is out. I don't think we should rely on that.
That is how a lot of the kernel works. Provide protypes only for code
that is semantically compiled, but can't ever be called due to
IS_ENABLED() checks. It took me a while to get used to it, but it
actually is pretty nice as the linker does the work for you to check
that it really is never called. Much better than say a BUILD_BUG_ON().
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next prev parent reply other threads:[~2019-09-06 14:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 11:33 swiotlb-xen cleanups v4 Christoph Hellwig
2019-09-05 11:33 ` [PATCH 01/11] xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance Christoph Hellwig
2019-09-10 0:18 ` Stefano Stabellini
2019-09-05 11:33 ` [PATCH 02/11] xen/arm: consolidate page-coherent.h Christoph Hellwig
2019-09-10 0:18 ` Stefano Stabellini
2019-09-05 11:34 ` [PATCH 03/11] xen/arm: use dev_is_dma_coherent Christoph Hellwig
2019-09-05 11:34 ` [PATCH 04/11] xen/arm: simplify dma_cache_maint Christoph Hellwig
2019-09-05 11:34 ` [PATCH 05/11] xen/arm: remove xen_dma_ops Christoph Hellwig
2019-09-05 11:34 ` [PATCH 06/11] xen: remove the exports for xen_{create, destroy}_contiguous_region Christoph Hellwig
2019-09-05 11:34 ` [PATCH 07/11] swiotlb-xen: remove xen_swiotlb_dma_mmap and xen_swiotlb_dma_get_sgtable Christoph Hellwig
2019-09-05 11:34 ` [PATCH 08/11] swiotlb-xen: use the same foreign page check everywhere Christoph Hellwig
2019-09-05 11:34 ` [PATCH 09/11] swiotlb-xen: simplify cache maintainance Christoph Hellwig
2019-09-06 13:52 ` Boris Ostrovsky
2019-09-06 14:01 ` Christoph Hellwig [this message]
2019-09-06 14:07 ` [Xen-devel] " Andrew Cooper
2019-09-06 14:19 ` Boris Ostrovsky
2019-09-06 14:43 ` Konrad Rzeszutek Wilk
2019-09-06 14:46 ` Boris Ostrovsky
2019-09-05 11:34 ` [PATCH 10/11] swiotlb-xen: merge xen_unmap_single into xen_swiotlb_unmap_page Christoph Hellwig
2019-09-05 11:34 ` [PATCH 11/11] arm64: use asm-generic/dma-mapping.h Christoph Hellwig
2019-09-11 10:45 ` swiotlb-xen cleanups v4 Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2019-08-16 13:00 swiotlb-xen cleanups Christoph Hellwig
2019-08-16 13:00 ` [PATCH 09/11] swiotlb-xen: simplify cache maintainance Christoph Hellwig
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