linux-kernel - [PATCH net-next 3/3] vsock/virtio: remove redundant `copy

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Date:   Fri, 18 Jun 2021 15:35:26 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Arseny Krasnov <arseny.krasnov@...persky.com>, kvm@...r.kernel.org,
        Stefano Garzarella <sgarzare@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        virtualization@...ts.linux-foundation.org,
        "David S. Miller" <davem@...emloft.net>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 3/3] vsock/virtio: remove redundant `copy_failed` variable

When memcpy_to_msg() fails in virtio_transport_seqpacket_do_dequeue(),
we already set `dequeued_len` with the negative error value returned
by memcpy_to_msg().

So we can directly check `dequeued_len` value instead of using a
dedicated flag variable to skip the copy path for the rest of
fragments.

Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
---
 net/vmw_vsock/virtio_transport_common.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 23704a6bc437..f014ccfdd9c2 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -413,7 +413,6 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
 	struct virtio_vsock_pkt *pkt;
 	int dequeued_len = 0;
 	size_t user_buf_len = msg_data_left(msg);
-	bool copy_failed = false;
 	bool msg_ready = false;
 
 	spin_lock_bh(&vvs->rx_lock);
@@ -426,7 +425,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
 	while (!msg_ready) {
 		pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list);
 
-		if (!copy_failed) {
+		if (dequeued_len >= 0) {
 			size_t pkt_len;
 			size_t bytes_to_copy;
 
@@ -443,11 +442,9 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
 
 				err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);
 				if (err) {
-					/* Copy of message failed, set flag to skip
-					 * copy path for rest of fragments. Rest of
+					/* Copy of message failed. Rest of
 					 * fragments will be freed without copy.
 					 */
-					copy_failed = true;
 					dequeued_len = err;
 				} else {
 					user_buf_len -= bytes_to_copy;
-- 
2.31.1