RDMA/ucma: Use refcount_t for the ctx->ref

Don't use an atomic as a refcount.

Link: https://lore.kernel.org/r/20200218191657.GA29724@ziepe.ca
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/ucma.c

@@ -85,7 +85,7 @@ struct ucma_file {
 struct ucma_context {
 	u32			id;
 	struct completion	comp;
-	atomic_t		ref;
+	refcount_t		ref;
 	int			events_reported;
 	int			backlog;
 
@@ -152,15 +152,15 @@ static struct ucma_context *ucma_get_ctx(struct ucma_file *file, int id)
 		if (ctx->closing)
 			ctx = ERR_PTR(-EIO);
 		else
-			atomic_inc(&ctx->ref);
+			refcount_inc(&ctx->ref);
 	}
 	xa_unlock(&ctx_table);
 	return ctx;
 }
 
 static void ucma_put_ctx(struct ucma_context *ctx)
 {
-	if (atomic_dec_and_test(&ctx->ref))
+	if (refcount_dec_and_test(&ctx->ref))
 		complete(&ctx->comp);
 }
 
@@ -212,7 +212,7 @@ static struct ucma_context *ucma_alloc_ctx(struct ucma_file *file)
 		return NULL;
 
 	INIT_WORK(&ctx->close_work, ucma_close_id);
-	atomic_set(&ctx->ref, 1);
+	refcount_set(&ctx->ref, 1);
 	init_completion(&ctx->comp);
 	INIT_LIST_HEAD(&ctx->mc_list);
 	ctx->file = file;
@@ -1502,7 +1502,7 @@ static ssize_t ucma_leave_multicast(struct ucma_file *file,
 		mc = ERR_PTR(-ENOENT);
 	else if (mc->ctx->file != file)
 		mc = ERR_PTR(-EINVAL);
-	else if (!atomic_inc_not_zero(&mc->ctx->ref))
+	else if (!refcount_inc_not_zero(&mc->ctx->ref))
 		mc = ERR_PTR(-ENXIO);
 	else
 		__xa_erase(&multicast_table, mc->id);