[3.13.y.z extended stable] Patch "dmaengine: fix dmaengine_unmap failure" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    dmaengine: fix dmaengine_unmap failure

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From edcc7cca0f0eea5fd24ade9081cdf0511d08c60b Mon Sep 17 00:00:00 2001
From: Xuelin Shi <xuelin.shi at freescale.com>
Date: Wed, 21 May 2014 14:02:37 -0700
Subject: dmaengine: fix dmaengine_unmap failure

commit c1f43dd9c20d85e66c4d77e284f64ac114abe3f8 upstream.

The count which is used to get_unmap_data maybe not the same as the
count computed in dmaengine_unmap which causes to free data in a
wrong pool.

This patch fixes this issue by keeping the map count with unmap_data
structure and use this count to get the pool.

Signed-off-by: Xuelin Shi <xuelin.shi at freescale.com>
Signed-off-by: Dan Williams <dan.j.williams at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/dma/dmaengine.c   | 2 ++
 include/linux/dmaengine.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ef63b90..b4c711d 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -959,6 +959,7 @@ static void dmaengine_unmap(struct kref *kref)
 		dma_unmap_page(dev, unmap->addr[i], unmap->len,
 			       DMA_BIDIRECTIONAL);
 	}
+	cnt = unmap->map_cnt;
 	mempool_free(unmap, __get_unmap_pool(cnt)->pool);
 }

@@ -1024,6 +1025,7 @@ dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags)
 	memset(unmap, 0, sizeof(*unmap));
 	kref_init(&unmap->kref);
 	unmap->dev = dev;
+	unmap->map_cnt = nr;

 	return unmap;
 }
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 41cf0c3..ed6c1f1 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -405,6 +405,7 @@ typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param);
 typedef void (*dma_async_tx_callback)(void *dma_async_param);

 struct dmaengine_unmap_data {
+	u8 map_cnt;
 	u8 to_cnt;
 	u8 from_cnt;
 	u8 bidi_cnt;
--
1.9.1