netdev - [RFC PATCH 08/22] rpmsg: virtio_rpmsg_bus: Disable receive virtqueue callback when reading messages

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Date:   Thu, 2 Jul 2020 13:51:29 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jon Mason <jdmason@...zu.us>,
        Dave Jiang <dave.jiang@...el.com>,
        Allen Hubbe <allenbh@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>
CC:     <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-ntb@...glegroups.com>,
        <linux-pci@...r.kernel.org>, <kvm@...r.kernel.org>,
        <virtualization@...ts.linux-foundation.org>,
        <netdev@...r.kernel.org>
Subject: [RFC PATCH 08/22] rpmsg: virtio_rpmsg_bus: Disable receive virtqueue callback when reading messages

Since rpmsg_recv_done() reads messages in a while loop, disable
callbacks until the while loop exits. This helps to get rid of the
annoying "uhm, incoming signal, but no used buffer ?" message.

Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
---
 drivers/rpmsg/virtio_rpmsg_bus.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index 376ebbf880d6..2d0d42084ac0 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -777,6 +777,7 @@ static void rpmsg_recv_done(struct virtqueue *rvq)
 		return;
 	}
 
+	virtqueue_disable_cb(rvq);
 	while (msg) {
 		err = rpmsg_recv_single(vrp, dev, msg, len);
 		if (err)
@@ -786,6 +787,19 @@ static void rpmsg_recv_done(struct virtqueue *rvq)
 
 		msg = virtqueue_get_buf(rvq, &len);
 	}
+	virtqueue_enable_cb(rvq);
+
+	/*
+	 * Try to read message one more time in case a new message is submitted
+	 * after virtqueue_get_buf() inside the while loop but before enabling
+	 * callbacks
+	 */
+	msg = virtqueue_get_buf(rvq, &len);
+	if (msg) {
+		err = rpmsg_recv_single(vrp, dev, msg, len);
+		if (!err)
+			msgs_received++;
+	}
 
 	dev_dbg(dev, "Received %u messages\n", msgs_received);
 
-- 
2.17.1