[PATCH 5/6] IB core: Fix ib_sg_to_pages()

[Bart Van Assche]

Fix the code for detecting gaps and disable the code for chunking.
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. Disable the code for chunking.
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 <h...@lst.de>
Signed-off-by: Bart Van Assche <bart.vanass...@sandisk.com>
Cc: stable <sta...@vger.kernel.org> # v4.4+
Cc: Sagi Grimberg <sa...@mellanox.com>
Cc: Sebastian Parschauer <sebastian.rie...@profitbricks.com>
---
 drivers/infiniband/core/verbs.c | 31 +++++++------------------------
 1 file changed, 7 insertions(+), 24 deletions(-)

diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 043a60e..95836c6 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -1530,10 +1530,9 @@ int ib_sg_to_pages(struct ib_mr *mr,
                   int (*set_page)(struct ib_mr *, u64))
 {
        struct scatterlist *sg;
-       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;
@@ -1544,37 +1543,21 @@ 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;
-                       }
-               }
+               /* gap */
+               if (i && (last_page_off || page_addr != dma_addr))
+                       break;
 
                do {
-                       if (unlikely(set_page(mr, page_addr)))
-                               goto done;
+                       ret = set_page(mr, page_addr);
+                       if (unlikely(ret < 0))
+                               return i ? i : ret;
                        page_addr += mr->page_size;
                } while (page_addr < end_dma_addr);
 
                mr->length += dma_len;
-               last_end_dma_addr = end_dma_addr;
-               last_page_addr = end_dma_addr & page_mask;
                last_page_off = end_dma_addr & ~page_mask;
        }
 
-done:
        return i;
 }
 EXPORT_SYMBOL(ib_sg_to_pages);
-- 
2.1.4

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