On 12/03/2015 01:18 AM, Christoph Hellwig wrote:
> The patch looks good to me, but while we touch this area, how about
> throwing in a few cosmetic fixes as well?
How about the patch below ? In that version of the ib_sg_to_pages() fix
these concerns have been addressed and additionally to more bugs have been fixed.
------------
[PATCH] IB core: Fix ib_sg_to_pages()
Fix the code for detecting gaps. A gap occurs not only if the
second or later scatterlist element is not aligned but also if
any scatterlist element other than the last does not end at a
page boundary.
In the code for coalescing contiguous elements, ensure that
mr->length is correct and that last_page_addr is up-to-date.
Ensure that this function returns a negative
error code instead of zero if the first set_page() call fails.
Fixes: commit 4c67e2bfc8b7 ("IB/core: Introduce new fast registration API")
Reported-by: Christoph Hellwig <hch@xxxxxx>
---
drivers/infiniband/core/verbs.c | 43 +++++++++++++++++++++--------------------
1 file changed, 22 insertions(+), 21 deletions(-)
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 043a60e..545906d 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -1516,7 +1516,7 @@ EXPORT_SYMBOL(ib_map_mr_sg);
* @sg_nents: number of entries in sg
* @set_page: driver page assignment function pointer
*
- * Core service helper for drivers to covert the largest
+ * Core service helper for drivers to convert the largest
* prefix of given sg list to a page vector. The sg list
* prefix converted is the prefix that meet the requirements
* of ib_map_mr_sg.
@@ -1533,7 +1533,7 @@ int ib_sg_to_pages(struct ib_mr *mr,
u64 last_end_dma_addr = 0, last_page_addr = 0;
unsigned int last_page_off = 0;
u64 page_mask = ~((u64)mr->page_size - 1);
- int i;
+ int i, ret;
mr->iova = sg_dma_address(&sgl[0]);
mr->length = 0;
@@ -1544,27 +1544,29 @@ int ib_sg_to_pages(struct ib_mr *mr,
u64 end_dma_addr = dma_addr + dma_len;
u64 page_addr = dma_addr & page_mask;
- if (i && page_addr != dma_addr) {
- if (last_end_dma_addr != dma_addr) {
- /* gap */
- goto done;
-
- } else if (last_page_off + dma_len <= mr->page_size) {
- /* chunk this fragment with the last */
- mr->length += dma_len;
- last_end_dma_addr += dma_len;
- last_page_off += dma_len;
- continue;
- } else {
- /* map starting from the next page */
- page_addr = last_page_addr + mr->page_size;
- dma_len -= mr->page_size - last_page_off;
- }
+ /*
+ * For the second and later elements, check whether either the
+ * end of element i-1 or the start of element i is not aligned
+ * on a page boundary.
+ */
+ if (i && (last_page_off != 0 || page_addr != dma_addr)) {
+ /* Stop mapping if there is a gap. */
+ if (last_end_dma_addr != dma_addr)
+ break;
+
+ /*
+ * Coalesce this element with the last. If it is small
+ * enough just update mr->length. Otherwise start
+ * mapping from the next page.
+ */
+ goto next_page;
}
do {
- if (unlikely(set_page(mr, page_addr)))
- goto done;
+ ret = set_page(mr, page_addr);
+ if (unlikely(ret < 0))
+ return i ? : ret;
+next_page:
page_addr += mr->page_size;
} while (page_addr < end_dma_addr);
@@ -1574,7 +1576,6 @@ int ib_sg_to_pages(struct ib_mr *mr,
last_page_off = end_dma_addr & ~page_mask;
}
-done:
return i;
}
EXPORT_SYMBOL(ib_sg_to_pages);
--
2.1.4
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