Hi Sagi-
> On Oct 6, 2015, at 5:48 AM, Sagi Grimberg <sagig@xxxxxxxxxxxx> wrote:
>
> There is no need to require LOCAL_DMA_LKEY support in order to
> use fast registration as the PD allocation makes sure that there
> is a local_dma_lkey.
In other words, all devices now have a local DMA lkey, so the
check is unnecessary.
> This caused a NULL pointer dereference in mlx5 which removed
> the support for LOCAL_DMA_LKEY.
Where was the bad dereference? in mlx5, or in xprtrdma?
> Fixes: bb6c96d72879 ("xprtrdma: Replace global lkey with lkey local to PD")
> Signed-off-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
> ---
> net/sunrpc/xprtrdma/verbs.c | 7 ++-----
> 1 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
> index eb081ad..7efd9ef 100644
> --- a/net/sunrpc/xprtrdma/verbs.c
> +++ b/net/sunrpc/xprtrdma/verbs.c
> @@ -543,11 +543,8 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
> }
>
> if (memreg == RPCRDMA_FRMR) {
> - /* Requires both frmr reg and local dma lkey */
> - if (((devattr->device_cap_flags &
> - (IB_DEVICE_MEM_MGT_EXTENSIONS|IB_DEVICE_LOCAL_DMA_LKEY)) !=
> - (IB_DEVICE_MEM_MGT_EXTENSIONS|IB_DEVICE_LOCAL_DMA_LKEY)) ||
> - (devattr->max_fast_reg_page_list_len == 0)) {
> + if (!(devattr->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) ||
> + (devattr->max_fast_reg_page_list_len == 0)) {
> dprintk("RPC: %s: FRMR registration "
> "not supported by HCA\n", __func__);
> memreg = RPCRDMA_MTHCAFMR;
Reviewed-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
—
Chuck Lever
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