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From: Logan Gunthorpe <logang@deltatee.com>
To: linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
	linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-s390@vger.kernel.org, sparclinux@vger.kernel.org,
	iommu@lists.linux-foundation.org, linux-parisc@vger.kernel.org,
	xen-devel@lists.xenproject.org
Cc: Christoph Hellwig <hch@lst.de>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Stephen Bates <sbates@raithlin.com>,
	Martin Oliveira <martin.oliveira@eideticom.com>,
	Logan Gunthorpe <logang@deltatee.com>
Subject: [PATCH v1 16/16] dma-mapping: Disallow .map_sg operations from returning zero on error
Date: Thu, 15 Jul 2021 10:45:44 -0600	[thread overview]
Message-ID: <20210715164544.6827-17-logang@deltatee.com> (raw)
In-Reply-To: <20210715164544.6827-1-logang@deltatee.com>

Now that all the .map_sg operations have been converted to returning
proper error codes, drop the code to handle a zero return value,
add a warning if a zero is returned and update the comment for the
map_sg operation.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
 include/linux/dma-map-ops.h | 8 +++-----
 kernel/dma/mapping.c        | 6 +++---
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index eaa969be8284..f299bc1e317b 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -42,11 +42,9 @@ struct dma_map_ops {
 			unsigned long attrs);
 	/*
 	 * map_sg should return a negative error code on error.
-	 * dma_map_sgtable() will return the error code returned and convert
-	 * a zero return (for legacy implementations) into -EINVAL.
-	 *
-	 * dma_map_sg() will always return zero on any negative or zero
-	 * return to satisfy its own calling convention.
+	 * dma_map_sgtable() will return the error code returned by the
+	 * operation and dma_map_sg() will always convert any error to zero
+	 * to satisfy its own calling convention.
 	 */
 	int (*map_sg)(struct device *dev, struct scatterlist *sg, int nents,
 			enum dma_data_direction dir, unsigned long attrs);
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 30f89d244566..978a6a16aaf7 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -194,6 +194,8 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
 	else
 		ents = ops->map_sg(dev, sg, nents, dir, attrs);
 
+	WARN_ON_ONCE(ents == 0);
+
 	if (ents > 0)
 		debug_dma_map_sg(dev, sg, nents, ents, dir);
 
@@ -251,9 +253,7 @@ int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
 	int nents;
 
 	nents = __dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs);
-	if (nents == 0)
-		return -EINVAL;
-	else if (nents < 0)
+	if (nents < 0)
 		return nents;
 
 	sgt->nents = nents;
-- 
2.20.1


  parent reply	other threads:[~2021-07-15 16:46 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-15 16:45 [PATCH v1 00/16] .map_sg() error cleanup Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 01/16] dma-mapping: Allow map_sg() ops to return negative error codes Logan Gunthorpe
2021-07-16  6:29   ` Christoph Hellwig
2021-07-15 16:45 ` [PATCH v1 02/16] dma-direct: Return appropriate error code from dma_direct_map_sg() Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 03/16] iommu: Return full error code from iommu_map_sg[_atomic]() Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 04/16] dma-iommu: Return error code from iommu_dma_map_sg() Logan Gunthorpe
2021-07-16  6:31   ` Christoph Hellwig
2021-07-15 16:45 ` [PATCH v1 05/16] alpha: return error code from alpha_pci_map_sg() Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 06/16] ARM/dma-mapping: return error code from .map_sg() ops Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 07/16] ia64/sba_iommu: return error code from sba_map_sg_attrs() Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 08/16] MIPS/jazzdma: return error code from jazz_dma_map_sg() Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 09/16] powerpc/iommu: return error code from .map_sg() ops Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 10/16] s390/pci: return error code from s390_dma_map_sg() Logan Gunthorpe
2021-07-16  8:24   ` Niklas Schnelle
2021-07-15 16:45 ` [PATCH v1 11/16] sparc/iommu: return error codes from .map_sg() ops Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 12/16] parisc: return error code " Logan Gunthorpe
2021-07-15 16:45 ` [PATCH v1 13/16] xen: swiotlb: return error code from xen_swiotlb_map_sg() Logan Gunthorpe
2021-07-19 20:22   ` Boris Ostrovsky
2021-07-15 16:45 ` [PATCH v1 14/16] x86/amd_gart: return error code from gart_map_sg() Logan Gunthorpe
2021-07-16  6:32   ` Christoph Hellwig
2021-07-16 12:11     ` Robin Murphy
2021-07-15 16:45 ` [PATCH v1 15/16] dma-mapping: return error code from dma_dummy_map_sg() Logan Gunthorpe
2021-07-15 16:45 ` Logan Gunthorpe [this message]
2021-07-16  6:33   ` [PATCH v1 16/16] dma-mapping: Disallow .map_sg operations from returning zero on error Christoph Hellwig
2021-07-16 12:19     ` Robin Murphy
2021-07-16 16:17     ` Logan Gunthorpe
2021-07-15 16:53 ` [PATCH v1 00/16] .map_sg() error cleanup Russell King (Oracle)
2021-07-15 16:56   ` Logan Gunthorpe

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