Re: [PATCH RFC] RDMA/CMA: Allocate PS_TCP ports from the host TCP port space.

Steve Wise
2007-08-09T18:50:27Z

Any more comments?

Steve Wise wrote:
> Networking experts,
>
> I'd like input on the patch below, and help in solving this bug
> properly. iWARP devices that support both native stack TCP and iWARP
> (aka RDMA over TCP/IP/Ethernet) connections on the same interface need
> the fix below or some similar fix to the RDMA connection manager.
>
> This is a BUG in the Linux RDMA-CMA code as it stands today.
>
> Here is the issue:
>
> Consider an mpi cluster running mvapich2. And the cluster runs
> MPI/Sockets jobs concurrently with MPI/RDMA jobs. It is possible,
> without the patch below, for MPI/Sockets processes to mistakenly get
> incoming RDMA connections and vice versa. The way mvapich2 works is
> that the ranks all bind and listen to a random port (retrying new random
> ports if the bind fails with "in use"). Once they get a free port and
> bind/listen, they advertise that port number to the peers to do
> connection setup. Currently, without the patch below, the mpi/rdma
> processes can end up binding/listening to the _same_ port number as the
> mpi/sockets processes running over the native tcp stack. This is due to
> duplicate port spaces for native stack TCP and the rdma cm's RDMA_PS_TCP
> port space. If this happens, then the connections can get screwed up.
>
> The correct solution in my mind is to use the host stack's TCP port
> space for _all_ RDMA_PS_TCP port allocations. The patch below is a
> minimal delta to unify the port spaces by using the kernel stack to bind
> ports. This is done by allocating a kernel socket and binding to the
> appropriate local addr/port. It also allows the kernel stack to pick
> ephemeral ports by virtue of just passing in port 0 on the kernel bind
> operation.
>
> There has been a discussion already on the RDMA list if anyone is
> interested:
>
> http://www.mail-archive.com/general@lists.openfabrics.org/msg05162.html
>
>
> Thanks,
>
> Steve.
>
>
> ---
>
> RDMA/CMA: Allocate PS_TCP ports from the host TCP port space.
>
> This is needed for iwarp providers that support native and rdma
> connections over the same interface.
>
> Signed-off-by: Steve Wise <swise@opengridcomputing.com>
> ---
>
> drivers/infiniband/core/cma.c | 27 ++++++++++++++++++++++++++-
> 1 files changed, 26 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index 9e0ab04..e4d2d7f 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -111,6 +111,7 @@ struct rdma_id_private {
> struct rdma_cm_id id;
>
> struct rdma_bind_list *bind_list;
> + struct socket *sock;
> struct hlist_node node;
> struct list_head list;
> struct list_head listen_list;
> @@ -695,6 +696,8 @@ static void cma_release_port(struct rdma
> kfree(bind_list);
> }
> mutex_unlock(&lock);
> + if (id_priv->sock)
> + sock_release(id_priv->sock);
> }
>
> void rdma_destroy_id(struct rdma_cm_id *id)
> @@ -1790,6 +1793,25 @@ static int cma_use_port(struct idr *ps,
> return 0;
> }
>
> +static int cma_get_tcp_port(struct rdma_id_private *id_priv)
> +{
> + int ret;
> + struct socket *sock;
> +
> + ret = sock_create_kern(AF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
> + if (ret)
> + return ret;
> + ret = sock->ops->bind(sock,
> + (struct sockaddr *)&id_priv->id.route.addr.src_addr,
> + ip_addr_size(&id_priv->id.route.addr.src_addr));
> + if (ret) {
> + sock_release(sock);
> + return ret;
> + }
> + id_priv->sock = sock;
> + return 0;
> +}
> +
> static int cma_get_port(struct rdma_id_private *id_priv)
> {
> struct idr *ps;
> @@ -1801,6 +1823,9 @@ static int cma_get_port(struct rdma_id_p
> break;
> case RDMA_PS_TCP:
> ps = &tcp_ps;
> + ret = cma_get_tcp_port(id_priv); /* Synch with native stack */
> + if (ret)
> + goto out;
> break;
> case RDMA_PS_UDP:
> ps = &udp_ps;
> @@ -1815,7 +1840,7 @@ static int cma_get_port(struct rdma_id_p
> else
> ret = cma_use_port(ps, id_priv);
> mutex_unlock(&lock);
> -
> +out:
> return ret;
> }
>
>
> -
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