[NET]: Fix kfifo_alloc() error check.

The return value of kfifo_alloc() should be checked by IS_ERR().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/probe.c b/net/dccp/probe.c
index 146496f..fded149 100644
--- a/net/dccp/probe.c
+++ b/net/dccp/probe.c
@@ -160,6 +160,8 @@
 	init_waitqueue_head(&dccpw.wait);
 	spin_lock_init(&dccpw.lock);
 	dccpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &dccpw.lock);
+	if (IS_ERR(dccpw.fifo))
+		return PTR_ERR(dccpw.fifo);
 
 	if (!proc_net_fops_create(procname, S_IRUSR, &dccpprobe_fops))
 		goto err0;