[PATCH 4.2.y-ckt 221/305] dma-debug: Fix dma_debug_entry offset calculation

From: Kamal Mostafa
Date: Fri Jan 15 2016 - 19:30:38 EST


4.2.8-ckt2 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Daniel Mentz <danielmentz@xxxxxxxxxx>

commit 0354aec19ce3d355c6213b0434064efc25c9b22c upstream.

dma-debug uses struct dma_debug_entry to keep track of dma coherent
memory allocation requests. The virtual address is converted into a pfn
and an offset. Previously, the offset was calculated using an incorrect
bit mask. As a result, we saw incorrect error messages from dma-debug
like the following:

"DMA-API: exceeded 7 overlapping mappings of cacheline 0x03e00000"

Cacheline 0x03e00000 does not exist on our platform.

Fixes: 0abdd7a81b7e ("dma-debug: introduce debug_dma_assert_idle()")
Signed-off-by: Daniel Mentz <danielmentz@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
lib/dma-debug.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index dace71f..c5fddeb 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1456,7 +1456,7 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size,
entry->type = dma_debug_coherent;
entry->dev = dev;
entry->pfn = page_to_pfn(virt_to_page(virt));
- entry->offset = (size_t) virt & PAGE_MASK;
+ entry->offset = (size_t) virt & ~PAGE_MASK;
entry->size = size;
entry->dev_addr = dma_addr;
entry->direction = DMA_BIDIRECTIONAL;
@@ -1472,7 +1472,7 @@ void debug_dma_free_coherent(struct device *dev, size_t size,
.type = dma_debug_coherent,
.dev = dev,
.pfn = page_to_pfn(virt_to_page(virt)),
- .offset = (size_t) virt & PAGE_MASK,
+ .offset = (size_t) virt & ~PAGE_MASK,
.dev_addr = addr,
.size = size,
.direction = DMA_BIDIRECTIONAL,
--
1.9.1