linux-kernel - [PATCH] dmaengine: ioat: Allocate correct size for descriptor chunk

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Message-Id: <20200922200844.2982-1-logang@deltatee.com>
Date:   Tue, 22 Sep 2020 14:08:44 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Logan Gunthorpe <logang@...tatee.com>,
        Robin Murphy <robin.murphy@....com>,
        Vinod Koul <vkoul@...nel.org>,
        Dave Jiang <dave.jiang@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH] dmaengine: ioat: Allocate correct size for descriptor chunk

dma_alloc_coherent() is called with a fixed SZ_2M size, but frees happen
with IOAT_CHUNK_SIZE. Recently, IOAT_CHUNK_SIZE was reduced to 512M but
the allocation did not change. To fix, change to using the
IOAT_CHUNK_SIZE define.

This was caught with the upcoming patchset for converting Intel platforms to the
dma-iommu implementation. It has a warning when the unmapped size differs from
the mapped size.

Fixes: a02254f8a676 ("dmaengine: ioat: Decreasing allocation chunk size 2M->512K")
Link: https://lore.kernel.org/intel-gfx/776771a2-247a-d1be-d882-bee02d919ae0@deltatee.com/
Suggested-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Cc: Vinod Koul <vkoul@...nel.org>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Dan Williams <dan.j.williams@...el.com>
---
 drivers/dma/ioat/dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index a814b200299b..07296171e2bb 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -389,7 +389,7 @@ ioat_alloc_ring(struct dma_chan *c, int order, gfp_t flags)
 		struct ioat_descs *descs = &ioat_chan->descs[i];
 
 		descs->virt = dma_alloc_coherent(to_dev(ioat_chan),
-						 SZ_2M, &descs->hw, flags);
+					IOAT_CHUNK_SIZE, &descs->hw, flags);
 		if (!descs->virt) {
 			int idx;
 

base-commit: ba4f184e126b751d1bffad5897f263108befc780
-- 
2.20.1