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/[EMAIL PROTECTED]/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 <[EMAIL PROTECTED]>
---
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 socketaddr *)&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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