RxRPC: Don't call skb_add_data() if there's no data to copy

Don't call skb_add_data() in rxrpc_send_data() if there's no data to copy and
also skip the calculations associated with it in such a case.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 19 insertions, 19 deletions

diff --git a/net/rxrpc/ar-output.c b/net/rxrpc/ar-output.c
index 833a33b5c180..f48dc1aa4840 100644
--- a/net/rxrpc/ar-output.c
+++ b/net/rxrpc/ar-output.c
@@ -549,8 +549,6 @@ static int rxrpc_send_data(struct kiocb *iocb,
         if (len > iov_iter_count(&msg->msg_iter))
                 len = iov_iter_count(&msg->msg_iter);
         do {
-                int copy;
-
                 if (!skb) {
                         size_t size, chunk, max, space;
 
@@ -616,23 +614,25 @@ static int rxrpc_send_data(struct kiocb *iocb,
                 sp = rxrpc_skb(skb);
 
                 /* append next segment of data to the current buffer */
-                copy = skb_tailroom(skb);
-                ASSERTCMP(copy, >, 0);
-                if (copy > len)
-                        copy = len;
-                if (copy > sp->remain)
-                        copy = sp->remain;
-
-                _debug("add");
-                ret = skb_add_data(skb, &msg->msg_iter, copy);
-                _debug("added");
-                if (ret < 0)
-                        goto efault;
-                sp->remain -= copy;
-                skb->mark += copy;
-                copied += copy;
-
-                len -= copy;
+                if (len > 0) {
+                        int copy = skb_tailroom(skb);
+                        ASSERTCMP(copy, >, 0);
+                        if (copy > len)
+                                copy = len;
+                        if (copy > sp->remain)
+                                copy = sp->remain;
+
+                        _debug("add");
+                        ret = skb_add_data(skb, &msg->msg_iter, copy);
+                        _debug("added");
+                        if (ret < 0)
+                                goto efault;
+                        sp->remain -= copy;
+                        skb->mark += copy;
+                        copied += copy;
+
+                        len -= copy;
+                }
 
                 /* check for the far side aborting the call or a network error
                  * occurring */