Thread (26 messages) 26 messages, 2 authors, 2021-06-30
STALE1792d

[RFC PATCH v1 10/16] virtio/vsock: update SEQPACKET dequeue logic

From: Arseny Krasnov <hidden>
Date: 2021-06-28 10:04:13
Also in: kvm, lkml
Subsystem: networking [general], the rest, virtio and vhost vsock driver, virtio core, vm sockets (af_vsock) · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Stefan Hajnoczi, Stefano Garzarella, "Michael S. Tsirkin", Jason Wang

As message copied by fragments, in addition to EOR met,
dequeue loop iterates until queue will be empty or copy
error found.

Signed-off-by: Arseny Krasnov <redacted>
---
 include/linux/virtio_vsock.h            |  1 -
 net/vmw_vsock/virtio_transport_common.c | 61 ++++++++++---------------
 2 files changed, 25 insertions(+), 37 deletions(-)
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 8d34f3d73bbb..7360ab7ea0af 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -36,7 +36,6 @@ struct virtio_vsock_sock {
 	u32 rx_bytes;
 	u32 buf_alloc;
 	struct list_head rx_queue;
-	u32 msg_count;
 };
 
 struct virtio_vsock_pkt {
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 9c2bd84ab8e6..5a46c3f94e83 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -407,59 +407,48 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
 
 static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
 						 struct msghdr *msg,
-						 int flags)
+						 int flags,
+						 bool *msg_ready)
 {
 	struct virtio_vsock_sock *vvs = vsk->trans;
 	struct virtio_vsock_pkt *pkt;
 	int dequeued_len = 0;
 	size_t user_buf_len = msg_data_left(msg);
-	bool msg_ready = false;
 
+	*msg_ready = false;
 	spin_lock_bh(&vvs->rx_lock);
 
-	if (vvs->msg_count == 0) {
-		spin_unlock_bh(&vvs->rx_lock);
-		return 0;
-	}
+	while (!*msg_ready && !list_empty(&vvs->rx_queue) && dequeued_len >= 0) {
+		size_t pkt_len;
+		size_t bytes_to_copy;
 
-	while (!msg_ready) {
 		pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list);
+		pkt_len = (size_t)le32_to_cpu(pkt->hdr.len);
 
-		if (dequeued_len >= 0) {
-			size_t pkt_len;
-			size_t bytes_to_copy;
+		bytes_to_copy = min(user_buf_len, pkt_len);
 
-			pkt_len = (size_t)le32_to_cpu(pkt->hdr.len);
-			bytes_to_copy = min(user_buf_len, pkt_len);
-
-			if (bytes_to_copy) {
-				int err;
-
-				/* sk_lock is held by caller so no one else can dequeue.
-				 * Unlock rx_lock since memcpy_to_msg() may sleep.
-				 */
-				spin_unlock_bh(&vvs->rx_lock);
+		if (bytes_to_copy) {
+			int err;
+			/* sk_lock is held by caller so no one else can dequeue.
+			 * Unlock rx_lock since memcpy_to_msg() may sleep.
+			 */
+			spin_unlock_bh(&vvs->rx_lock);
 
-				err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);
-				if (err) {
-					/* Copy of message failed. Rest of
-					 * fragments will be freed without copy.
-					 */
-					dequeued_len = err;
-				} else {
-					user_buf_len -= bytes_to_copy;
-				}
+			err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);
 
-				spin_lock_bh(&vvs->rx_lock);
-			}
+			spin_lock_bh(&vvs->rx_lock);
 
-			if (dequeued_len >= 0)
-				dequeued_len += pkt_len;
+			if (err)
+				dequeued_len = err;
+			else
+				user_buf_len -= bytes_to_copy;
 		}
 
+		if (dequeued_len >= 0)
+			dequeued_len += pkt_len;
+
 		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR) {
-			msg_ready = true;
-			vvs->msg_count--;
+			*msg_ready = true;
 		}
 
 		virtio_transport_dec_rx_pkt(vvs, pkt);
@@ -494,7 +483,7 @@ virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
 	if (flags & MSG_PEEK)
 		return -EOPNOTSUPP;
 
-	return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
+	return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags, msg_ready);
 }
 EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
 
-- 
2.25.1
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help