Re: [PATCH rdma-rc] xprtrdma: Don't require LOCAL_DMA_LKEY support for fasterg

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On 10/6/2015 6:05 PM, Chuck Lever wrote:
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.

Right.



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?

xprtrdma, ia->ri_ops wasn't assigned correctly.

Now that I look at it, one error path in rpcrdma_ia_open misses
an rc assignment. That needs to be fixed too, should it be in the same
patch?

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 7efd9ef..81e8d31 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -554,6 +554,7 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
                if (!ia->ri_device->alloc_fmr) {
                        dprintk("RPC:       %s: MTHCAFMR registration "
                                "not supported by HCA\n", __func__);
+                       rc = -EINVAL;
                        goto out3;
                }
        }
--

the incorrect requirement + missing rc caused the NULL deref of
ia->ri_ops.
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