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SubjectRE: [PATCH] dmaengine: async_xor, fix zero address issue when xor highmem page
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Hello Dan Williams,

Do you have any comment about this patch?

Thanks,
Forrest

-----Original Message-----
From: Shi Xuelin-B29237
Sent: 2011年12月27日 14:31
To: vinod.koul@intel.com; dan.j.williams@intel.com; linuxppc-dev@lists.ozlabs.org; linux-kernel@vger.kernel.org; Li Yang-R58472
Cc: Shi Xuelin-B29237
Subject: [PATCH] dmaengine: async_xor, fix zero address issue when xor highmem page
From: Forrest shi <b29237@freescale.com>

we may do_sync_xor high mem pages, in this case, page_address will
return zero address which cause a failure.

this patch uses kmap_atomic before xor the pages and kunmap_atomic
after it.

Signed-off-by: b29237@freescale.com <xuelin.shi@freescale.com>
---
crypto/async_tx/async_xor.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c index bc28337..5b416d1 100644
--- a/crypto/async_tx/async_xor.c
+++ b/crypto/async_tx/async_xor.c
@@ -26,6 +26,7 @@
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
+#include <linux/highmem.h>
#include <linux/dma-mapping.h>
#include <linux/raid/xor.h>
#include <linux/async_tx.h>
@@ -126,7 +127,7 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
int src_cnt, size_t len, struct async_submit_ctl *submit) {
int i;
- int xor_src_cnt = 0;
+ int xor_src_cnt = 0, kmap_cnt=0;
int src_off = 0;
void *dest_buf;
void **srcs;
@@ -138,11 +139,13 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,

/* convert to buffer pointers */
for (i = 0; i < src_cnt; i++)
- if (src_list[i])
- srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
+ if (src_list[i]) {
+ srcs[xor_src_cnt++] = kmap_atomic(src_list[i], KM_USER1) + offset;
+ }
+ kmap_cnt = xor_src_cnt;
src_cnt = xor_src_cnt;
/* set destination address */
- dest_buf = page_address(dest) + offset;
+ dest_buf = kmap_atomic(dest, KM_USER0) + offset;

if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
memset(dest_buf, 0, len);
@@ -157,6 +160,11 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
src_off += xor_src_cnt;
}

+ kunmap_atomic(dest_buf, KM_USER0);
+ for (i = 0; i < kmap_cnt; i++)
+ if (src_list[i])
+ kunmap_atomic(srcs[i], KM_USER1);
+
async_tx_sync_epilog(submit);
}

--
1.7.0.4



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