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IB core: Fix ib_sg_to_pages()

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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 4c67e2bfc8 ("IB/core: Introduce new fast registration API")
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Bart Van Assche 2015-12-03 16:04:17 -08:00 committed by Doug Ledford
parent 57b0be9c0f
commit 8f5ba10ed4
1 changed files with 21 additions and 20 deletions
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41
drivers/infiniband/core/verbs.c
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@ -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;
/*
* 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;
} 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;
}
/*
* 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);