linux-kernel - [PATCH] ia64: fix SBA IOMMU to handle allocation failure properly

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Message-Id: <20091018140631K.fujita.tomonori@lab.ntt.co.jp>
Date:	Sun, 18 Oct 2009 14:07:04 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	tony.luck@...el.com, linux-ia64@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, lchiquitto@...ell.com
Subject: [PATCH] ia64: fix SBA IOMMU to handle allocation failure properly

This is an updated patch of the patch that I've posted one year
ago. Shehjar reported the problem and confirmed that the patch fixes
it:

http://lkml.indiana.edu/hypermail/linux/kernel/0811.0/01562.html

Leonardo told me that he hit the same problem and confirmed that the
patch fixes it.

=
From: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Subject: [PATCH] ia64: fix SBA IOMMU to handle allocation failure properly

It's possible that SBA IOMMU might fail to find I/O space under heavy
I/Os. SBA IOMMU panics on allocation failure but it shouldn't; drivers
can handle the failure. The majority of other IOMMU drivers don't
panic on allocation failure.

This patch fixes SBA IOMMU path to handle allocation failure properly.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
---
 arch/ia64/hp/common/sba_iommu.c |   38 +++++++++++++++++++++++++++++---------
 1 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index 674a837..01ae69b 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -677,12 +677,19 @@ sba_alloc_range(struct ioc *ioc, struct device *dev, size_t size)
 			spin_unlock_irqrestore(&ioc->saved_lock, flags);
 
 			pide = sba_search_bitmap(ioc, dev, pages_needed, 0);
-			if (unlikely(pide >= (ioc->res_size << 3)))
-				panic(__FILE__ ": I/O MMU @ %p is out of mapping resources\n",
-				      ioc->ioc_hpa);
+			if (unlikely(pide >= (ioc->res_size << 3))) {
+				printk(KERN_WARNING "%s: I/O MMU @ %p is"
+				       "out of mapping resources, %u %u %lx\n",
+				       __func__, ioc->ioc_hpa, ioc->res_size,
+				       pages_needed, dma_get_seg_boundary(dev));
+				return -1;
+			}
 #else
-			panic(__FILE__ ": I/O MMU @ %p is out of mapping resources\n",
-			      ioc->ioc_hpa);
+			printk(KERN_WARNING "%s: I/O MMU @ %p is"
+			       "out of mapping resources, %u %u %lx\n",
+			       __func__, ioc->ioc_hpa, ioc->res_size,
+			       pages_needed, dma_get_seg_boundary(dev));
+			return -1;
 #endif
 		}
 	}
@@ -965,6 +972,8 @@ static dma_addr_t sba_map_page(struct device *dev, struct page *page,
 #endif
 
 	pide = sba_alloc_range(ioc, dev, size);
+	if (pide < 0)
+		return 0;
 
 	iovp = (dma_addr_t) pide << iovp_shift;
 
@@ -1320,6 +1329,7 @@ sba_coalesce_chunks(struct ioc *ioc, struct device *dev,
 	unsigned long dma_offset, dma_len; /* start/len of DMA stream */
 	int n_mappings = 0;
 	unsigned int max_seg_size = dma_get_max_seg_size(dev);
+	int idx;
 
 	while (nents > 0) {
 		unsigned long vaddr = (unsigned long) sba_sg_address(startsg);
@@ -1418,16 +1428,22 @@ sba_coalesce_chunks(struct ioc *ioc, struct device *dev,
 		vcontig_sg->dma_length = vcontig_len;
 		dma_len = (dma_len + dma_offset + ~iovp_mask) & iovp_mask;
 		ASSERT(dma_len <= DMA_CHUNK_SIZE);
-		dma_sg->dma_address = (dma_addr_t) (PIDE_FLAG
-			| (sba_alloc_range(ioc, dev, dma_len) << iovp_shift)
-			| dma_offset);
+		idx = sba_alloc_range(ioc, dev, dma_len);
+		if (idx < 0) {
+			dma_sg->dma_length = 0;
+			return -1;
+		}
+		dma_sg->dma_address = (dma_addr_t)(PIDE_FLAG | (idx << iovp_shift)
+						   | dma_offset);
 		n_mappings++;
 	}
 
 	return n_mappings;
 }
 
-
+static void sba_unmap_sg_attrs(struct device *dev, struct scatterlist *sglist,
+			       int nents, enum dma_data_direction dir,
+			       struct dma_attrs *attrs);
 /**
  * sba_map_sg - map Scatter/Gather list
  * @dev: instance of PCI owned by the driver that's asking.
@@ -1493,6 +1509,10 @@ static int sba_map_sg_attrs(struct device *dev, struct scatterlist *sglist,
 	** Access to the virtual address is what forces a two pass algorithm.
 	*/
 	coalesced = sba_coalesce_chunks(ioc, dev, sglist, nents);
+	if (coalesced < 0) {
+		sba_unmap_sg_attrs(dev, sglist, nents, dir, attrs);
+		return 0;
+	}
 
 	/*
 	** Program the I/O Pdir
-- 
1.5.6.5

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