RDMA/addr: Use client registration to fix module unload race

Require registration with ib_addr module to prevent caller from
unloading while a callback is in progress.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 27 insertions, 1 deletions

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index 60d3fbdd216c..e11187ecc931 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -47,6 +47,7 @@ struct addr_req {
         struct sockaddr src_addr;
         struct sockaddr dst_addr;
         struct rdma_dev_addr *addr;
+        struct rdma_addr_client *client;
         void *context;
         void (*callback)(int status, struct sockaddr *src_addr,
                          struct rdma_dev_addr *addr, void *context);
@@ -61,6 +62,26 @@ static LIST_HEAD(req_list);
 static DECLARE_WORK(work, process_req, NULL);
 static struct workqueue_struct *addr_wq;
 
+void rdma_addr_register_client(struct rdma_addr_client *client)
+{
+        atomic_set(&client->refcount, 1);
+        init_completion(&client->comp);
+}
+EXPORT_SYMBOL(rdma_addr_register_client);
+
+static inline void put_client(struct rdma_addr_client *client)
+{
+        if (atomic_dec_and_test(&client->refcount))
+                complete(&client->comp);
+}
+
+void rdma_addr_unregister_client(struct rdma_addr_client *client)
+{
+        put_client(client);
+        wait_for_completion(&client->comp);
+}
+EXPORT_SYMBOL(rdma_addr_unregister_client);
+
 int rdma_copy_addr(struct rdma_dev_addr *dev_addr, struct net_device *dev,
                      const unsigned char *dst_dev_addr)
 {
@@ -229,6 +250,7 @@ static void process_req(void *data)
                 list_del(&req->list);
                 req->callback(req->status, &req->src_addr, req->addr,
                               req->context);
+                put_client(req->client);
                 kfree(req);
         }
 }
@@ -264,7 +286,8 @@ static int addr_resolve_local(struct sockaddr_in *src_in,
         return ret;
 }
 
-int rdma_resolve_ip(struct sockaddr *src_addr, struct sockaddr *dst_addr,
+int rdma_resolve_ip(struct rdma_addr_client *client,
+                    struct sockaddr *src_addr, struct sockaddr *dst_addr,
                     struct rdma_dev_addr *addr, int timeout_ms,
                     void (*callback)(int status, struct sockaddr *src_addr,
                                      struct rdma_dev_addr *addr, void *context),
@@ -285,6 +308,8 @@ int rdma_resolve_ip(struct sockaddr *src_addr, struct sockaddr *dst_addr,
         req->addr = addr;
         req->callback = callback;
         req->context = context;
+        req->client = client;
+        atomic_inc(&client->refcount);
 
         src_in = (struct sockaddr_in *) &req->src_addr;
         dst_in = (struct sockaddr_in *) &req->dst_addr;
@@ -305,6 +330,7 @@ int rdma_resolve_ip(struct sockaddr *src_addr, struct sockaddr *dst_addr,
                 break;
         default:
                 ret = req->status;
+                atomic_dec(&client->refcount);
                 kfree(req);
                 break;
         }