[ofa-general] [PATCH 2/3] RDMA/cxgb3: fix page shift calculation in build_phys_page_list()

[Steve Wise]

Roland Dreier wrote:
> 
> I think the patch below should be a fix for the problem, although I've
> only compile tested it.  The idea is to stop increasing shift once it
> reaches a bit position where the first buffer and the iova differ.
> What do you think?  If this works for you, I will merge it for 2.6.25.
> 
> diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
> index 6bcde1c..1a15129 100644
> --- a/drivers/infiniband/hw/mthca/mthca_provider.c
> +++ b/drivers/infiniband/hw/mthca/mthca_provider.c
> @@ -948,7 +948,9 @@ static struct ib_mr *mthca_reg_phys_mr(struct ib_pd       *pd,
>  		return ERR_PTR(-EINVAL);
>  
>  	/* Find largest page shift we can use to cover buffers */
> -	for (shift = PAGE_SHIFT; shift < 31; ++shift)
> +	for (shift = PAGE_SHIFT; shift < 31; ++shift) {
> +		if ((buffer_list[0].addr ^ *iova_start) & (1ULL << shift))
> +			break;
>  		if (num_phys_buf > 1) {
>  			if ((1ULL << shift) & mask)
>  				break;
> @@ -958,6 +960,7 @@ static struct ib_mr *mthca_reg_phys_mr(struct ib_pd       *pd,
>  			    (buffer_list[0].addr & ((1ULL << shift) - 1)))
>  				break;
>  		}
> +	}
>  
>  	buffer_list[0].size += buffer_list[0].addr & ((1ULL << shift) - 1);
>  	buffer_list[0].addr &= ~0ull << shift;


I wonder if we should make this functionality common and put it in 
infiniband/drivers/core somewhere?  I think mthca and cxgb3 need the 
same service.  Probably ehca and nes too...

Steve.