3.16.52-rc1 review patch. If anyone has any objections, please let me know.
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From: Ilya Lesokhin ilyal@mellanox.com
commit d67bc5d4e3e100d762c0f57ea67f28bc219698a6 upstream.
The patch simplifies mlx5_ib_cont_pages and fixes the following issues in the original implementation:
First issues is related to alignment of the PFNs. After the check base + p != PFN, the alignment of the PFN wasn't checked. So the PFN sequence 0, 1, 1, 2 would result in a page_shift of 13 even though the 3rd PFN is not 8KB aligned.
This wasn't actually a bug because it was supported by all the existing mlx5 compatible device, but we don't want to require this support in all future devices.
Another issue is because the inner loop didn't advance PFN so the test "if (base + p != pfn)" always failed for SGE with len > (1<<page_shift).
Fixes: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters") Signed-off-by: Ilya Lesokhin ilyal@mellanox.com Reviewed-by: Eli Cohen eli@mellanox.com Signed-off-by: Leon Romanovsky leon@kernel.org Signed-off-by: Doug Ledford dledford@redhat.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/infiniband/hw/mlx5/mem.c | 47 +++++++++++++++------------------------- 1 file changed, 17 insertions(+), 30 deletions(-)
--- a/drivers/infiniband/hw/mlx5/mem.c +++ b/drivers/infiniband/hw/mlx5/mem.c @@ -46,46 +46,33 @@ void mlx5_ib_cont_pages(struct ib_umem * { unsigned long tmp; unsigned long m; - int i, k; - u64 base = 0; - int p = 0; - int skip; - int mask; - u64 len; - u64 pfn; + u64 base = ~0, p = 0; + u64 len, pfn; + int i = 0; struct scatterlist *sg; int entry;
addr = addr >> PAGE_SHIFT; tmp = (unsigned long)addr; m = find_first_bit(&tmp, BITS_PER_LONG); - skip = 1 << m; - mask = skip - 1; - i = 0; + for_each_sg(umem->sg_head.sgl, sg, umem->nmap, entry) { len = sg_dma_len(sg) >> PAGE_SHIFT; pfn = sg_dma_address(sg) >> PAGE_SHIFT; - for (k = 0; k < len; k++) { - if (!(i & mask)) { - tmp = (unsigned long)pfn; - m = min_t(unsigned long, m, find_first_bit(&tmp, BITS_PER_LONG)); - skip = 1 << m; - mask = skip - 1; - base = pfn; - p = 0; - } else { - if (base + p != pfn) { - tmp = (unsigned long)p; - m = find_first_bit(&tmp, BITS_PER_LONG); - skip = 1 << m; - mask = skip - 1; - base = pfn; - p = 0; - } - } - p++; - i++; + if (base + p != pfn) { + /* If either the offset or the new + * base are unaligned update m + */ + tmp = (unsigned long)(pfn | p); + if (!IS_ALIGNED(tmp, 1 << m)) + m = find_first_bit(&tmp, BITS_PER_LONG); + + base = pfn; + p = 0; } + + p += len; + i += len; }
if (i) {