[PATCH] svcrdma: Handle device removal outside of the CM event handler

[cel@kernel.org]

From: Chuck Lever <chuck.lever@oracle.com>

Synchronously wait for all disconnects to complete to ensure the
transports have divested all hardware resources before the
underlying RDMA device can safely be removed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/svc_rdma.h          |  2 ++
 include/trace/events/rpcrdma.h           | 23 +++++++++++++++++++++++
 net/sunrpc/xprtrdma/svc_rdma_transport.c | 16 +++++++++++++++-
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index d33bab33099a..619fc0bd837a 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -48,6 +48,7 @@
 #include <linux/sunrpc/rpc_rdma.h>
 #include <linux/sunrpc/rpc_rdma_cid.h>
 #include <linux/sunrpc/svc_rdma_pcl.h>
+#include <linux/sunrpc/rdma_rn.h>
 
 #include <linux/percpu_counter.h>
 #include <rdma/ib_verbs.h>
@@ -76,6 +77,7 @@ struct svcxprt_rdma {
 	struct svc_xprt      sc_xprt;		/* SVC transport structure */
 	struct rdma_cm_id    *sc_cm_id;		/* RDMA connection id */
 	struct list_head     sc_accept_q;	/* Conn. waiting accept */
+	struct rpcrdma_notification sc_rn;	/* removal notification */
 	int		     sc_ord;		/* RDMA read limit */
 	int                  sc_max_send_sges;
 	bool		     sc_snd_w_inv;	/* OK to use Send With Invalidate */
diff --git a/include/trace/events/rpcrdma.h b/include/trace/events/rpcrdma.h
index ba2d6a0e41cc..9141398591e0 100644
--- a/include/trace/events/rpcrdma.h
+++ b/include/trace/events/rpcrdma.h
@@ -2172,6 +2172,29 @@ TRACE_EVENT(svcrdma_qp_error,
 	)
 );
 
+TRACE_EVENT(svcrdma_device_removal,
+	TP_PROTO(
+		const struct rdma_cm_id *id
+	),
+
+	TP_ARGS(id),
+
+	TP_STRUCT__entry(
+		__string(name, id->device->name)
+		__array(unsigned char, addr, sizeof(struct sockaddr_in6))
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		memcpy(__entry->addr, &id->route.addr.dst_addr,
+		       sizeof(struct sockaddr_in6));
+	),
+
+	TP_printk("device %s to be removed, disconnecting %pISpc\n",
+		__get_str(name), __entry->addr
+	)
+);
+
 DECLARE_EVENT_CLASS(svcrdma_sendqueue_class,
 	TP_PROTO(
 		const struct svcxprt_rdma *rdma,
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index f15750cacacf..581cc5ed7c0c 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -339,7 +339,6 @@ static int svc_rdma_cma_handler(struct rdma_cm_id *cma_id,
 		svc_xprt_enqueue(xprt);
 		break;
 	case RDMA_CM_EVENT_DISCONNECTED:
-	case RDMA_CM_EVENT_DEVICE_REMOVAL:
 		svc_xprt_deferred_close(xprt);
 		break;
 	default:
@@ -384,6 +383,16 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 	return &cma_xprt->sc_xprt;
 }
 
+static void svc_rdma_xprt_done(struct rpcrdma_notification *rn)
+{
+	struct svcxprt_rdma *rdma = container_of(rn, struct svcxprt_rdma,
+						 sc_rn);
+	struct rdma_cm_id *id = rdma->sc_cm_id;
+
+	trace_svcrdma_device_removal(id);
+	svc_xprt_close(&rdma->sc_xprt);
+}
+
 /*
  * This is the xpo_recvfrom function for listening endpoints. Its
  * purpose is to accept incoming connections. The CMA callback handler
@@ -425,6 +434,9 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	dev = newxprt->sc_cm_id->device;
 	newxprt->sc_port_num = newxprt->sc_cm_id->port_num;
 
+	if (rpcrdma_rn_register(dev, &newxprt->sc_rn, svc_rdma_xprt_done))
+		goto errout;
+
 	newxprt->sc_max_req_size = svcrdma_max_req_size;
 	newxprt->sc_max_requests = svcrdma_max_requests;
 	newxprt->sc_max_bc_requests = svcrdma_max_bc_requests;
@@ -580,6 +592,7 @@ static void __svc_rdma_free(struct work_struct *work)
 {
 	struct svcxprt_rdma *rdma =
 		container_of(work, struct svcxprt_rdma, sc_work);
+	struct ib_device *device = rdma->sc_cm_id->device;
 
 	/* This blocks until the Completion Queues are empty */
 	if (rdma->sc_qp && !IS_ERR(rdma->sc_qp))
@@ -608,6 +621,7 @@ static void __svc_rdma_free(struct work_struct *work)
 	/* Destroy the CM ID */
 	rdma_destroy_id(rdma->sc_cm_id);
 
+	rpcrdma_rn_unregister(device, &rdma->sc_rn);
 	kfree(rdma);
 }
 
-- 
2.45.2