linux-kernel - [PATCH resend] virtio_console: Free buffers from out-queue upon close

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Message-Id: <1352295822-22906-1-git-send-email-sjur.brandeland@stericsson.com>
Date:	Wed,  7 Nov 2012 14:43:42 +0100
From:	sjur.brandeland@...ricsson.com
To:	Amit Shah <amit.shah@...hat.com>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org, sjur@...ndeland.net,
	Sjur Brændeland <sjur.brandeland@...ricsson.com>
Subject: [PATCH resend] virtio_console: Free buffers from out-queue upon close

From: Sjur Brændeland <sjur.brandeland@...ricsson.com>

Free pending output buffers from the virtio out-queue when
host has acknowledged port_close. Also removed WARN_ON()
in remove_port_data().

Signed-off-by: Sjur Brændeland <sjur.brandeland@...ricsson.com>
---

Resending, this time including a proper "Subject"...
--

Hi Amit,

Note: This patch is compile tested only. I have done the removal
of buffers from out-queue in handle_control_message()
when host has acked the close request. This seems less
racy than doing it in the release function.

I you want to change this further, feel free to take over from
here and refine this.

Thanks,
Sjur

 drivers/char/virtio_console.c |   14 ++++++--------
 1 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3fa036a..3a5831d 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1522,15 +1522,9 @@ static void remove_port_data(struct port *port)
 	while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
 		free_buf(buf, true);
 
-	/*
-	 * Check the out-queue for buffers. For VIRTIO_CONSOLE it is a
-	 * bug if this happens. But for RPROC_SERIAL the remote processor
-	 * may have crashed, leaving buffers hanging in the out-queue.
-	 */
-	while ((buf = virtqueue_detach_unused_buf(port->out_vq))) {
-		WARN_ON_ONCE(!is_rproc_serial(port->portdev->vdev));
+	/* Free pending buffers from the out-queue. */
+	while ((buf = virtqueue_detach_unused_buf(port->out_vq)))
 		free_buf(buf, true);
-	}
 }
 
 /*
@@ -1655,6 +1649,10 @@ static void handle_control_message(struct ports_device *portdev,
 		 */
 		spin_lock_irq(&port->outvq_lock);
 		reclaim_consumed_buffers(port);
+
+		/* Free pending buffers from the out-queue. */
+		while ((buf = virtqueue_detach_unused_buf(port->out_vq)))
+			free_buf(buf, true);
 		spin_unlock_irq(&port->outvq_lock);
 
 		/*
-- 
1.7.5.4

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