From 9ff4cfab82d27e9fda72315f911bbaa9516e04bc Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Thu, 8 Apr 2010 09:46:16 -0600
Subject: [PATCH] virtio: console makes incorrect assumption about virtio API
The get_buf() API sets the second arg to the number of bytes *written*
by the other side; in this case it should be zero as these are output buffers.
lguest gets this right (obviously kvm's console doesn't), resulting in
continual buildup of console writes.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Amit Shah <amit.shah@redhat.com>
---
drivers/char/virtio_console.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 48306bc733f7..86e9011325dc 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -416,20 +416,16 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count)
out_vq->vq_ops->kick(out_vq);
if (ret < 0) {
- len = 0;
+ in_count = 0;
goto fail;
}
- /*
- * Wait till the host acknowledges it pushed out the data we
- * sent. Also ensure we return to userspace the number of
- * bytes that were successfully consumed by the host.
- */
+ /* Wait till the host acknowledges it pushed out the data we sent. */
while (!out_vq->vq_ops->get_buf(out_vq, &len))
cpu_relax();
fail:
/* We're expected to return the amount of data we wrote */
- return len;
+ return in_count;
}
/*
--
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