linux-kernel - Re: [PATCH v3 1/7] iommu: Move iotlb_sync_map out from __iommu

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Message-ID: <1608809257.26323.259.camel@mhfsdcap03>
Date:   Thu, 24 Dec 2020 19:27:37 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Christoph Hellwig <hch@...radead.org>
CC:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        "Robin Murphy" <robin.murphy@....com>, <youlin.pei@...iatek.com>,
        <anan.sun@...iatek.com>, Nicolas Boichat <drinkcat@...omium.org>,
        <srv_heupstream@...iatek.com>, <chao.hao@...iatek.com>,
        <linux-kernel@...r.kernel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Tomasz Figa" <tfiga@...gle.com>,
        <iommu@...ts.linux-foundation.org>,
        <linux-mediatek@...ts.infradead.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Greg Kroah-Hartman <gregkh@...gle.com>,
        <kernel-team@...roid.com>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 1/7] iommu: Move iotlb_sync_map out from __iommu_map

On Wed, 2020-12-23 at 08:51 +0000, Christoph Hellwig wrote:
> On Wed, Dec 16, 2020 at 06:36:01PM +0800, Yong Wu wrote:
> > In the end of __iommu_map, It alway call iotlb_sync_map.
> > This patch moves iotlb_sync_map out from __iommu_map since it is
> > unnecessary to call this for each sg segment especially iotlb_sync_map
> > is flush tlb all currently.
> > 
> > Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> > Reviewed-by: Robin Murphy <robin.murphy@....com>
> 
> What about adding a little helper that does the NULL check and method
> call instead of duplicating it all over?

Thanks for the review. Of course OK.

Then the code like below. 
(If the helper name "_iommu_map" is not good, please tell me.)

+static int _iommu_map(struct iommu_domain *domain, unsigned long iova,
+		       phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
+{
+	const struct iommu_ops *ops = domain->ops;
+	int ret;
+
+	ret = __iommu_map(domain, iova, paddr, size, prot, gfp);
+	if (ret == 0 && ops->iotlb_sync_map)
+		ops->iotlb_sync_map(domain);
+	return ret;
+}
+
 int iommu_map(struct iommu_domain *domain, unsigned long iova,
 	      phys_addr_t paddr, size_t size, int prot)
 {
 	might_sleep();
-	return __iommu_map(domain, iova, paddr, size, prot, GFP_KERNEL);
+	return _iommu_map(domain, iova, paddr, size, prot, GFP_KERNEL);
 }
 EXPORT_SYMBOL_GPL(iommu_map);
 
 int iommu_map_atomic(struct iommu_domain *domain, unsigned long iova,
 	      phys_addr_t paddr, size_t size, int prot)
 {
-	return __iommu_map(domain, iova, paddr, size, prot, GFP_ATOMIC);
+	return _iommu_map(domain, iova, paddr, size, prot, GFP_ATOMIC);
 }
 EXPORT_SYMBOL_GPL(iommu_map_atomic);