On 2012/2/1,星期三 16:12, Amit Shah wrote:
Hi,
Sorry for the late reply.
On (Thu) 12 Jan 2012 [09:20:07], zanghongyong@xxxxxxxxxx wrote:
From: Hongyong Zang<zanghongyong@xxxxxxxxxx>
Add setup_port_vq(). Create the io ports' vqs when add_port.
Can you describe the changes in more detail, please?
The motivation of this patch is as follows. When we use virtio-serial
for communication between guest and host, we usually use only a few
ports (for example 1 or 2 ports), so there's no need to create max ports
when build a virtio-serial. The patch does the port hot-plug thing without
port hot-unplug.
Signed-off-by: Hongyong Zang<zanghongyong@xxxxxxxxxx>
---
drivers/char/virtio_console.c | 65 ++++++++++++++++++++++++++++++++++++++--
1 files changed, 61 insertions(+), 4 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 8e3c46d..2e5187e 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1132,6 +1132,55 @@ static void send_sigio_to_port(struct port *port)
kill_fasync(&port->async_queue, SIGIO, POLL_OUT);
}
+static void in_intr(struct virtqueue *vq);
+static void out_intr(struct virtqueue *vq);
+
+static int setup_port_vq(struct ports_device *portdev, u32 id)
+{
+ int err, vq_num;
+ vq_callback_t **io_callbacks;
+ char **io_names;
+ struct virtqueue **vqs;
+ u32 i,j,nr_ports,nr_queues;
+
+ err = 0;
+ vq_num = (id + 1) * 2;
+ nr_ports = portdev->config.max_nr_ports;
+ nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;
+
+ vqs = kmalloc(nr_queues * sizeof(struct virtqueue *), GFP_KERNEL);
+ io_callbacks = kmalloc(nr_queues * sizeof(vq_callback_t *), GFP_KERNEL);
+ io_names = kmalloc(nr_queues * sizeof(char *), GFP_KERNEL);
+ if (!vqs || !io_callbacks || !io_names) {
+ err = -ENOMEM;
+ goto free;
+ }
+
+ for (i = 0, j = 0; i<= nr_ports; i++) {
+ io_callbacks[j] = in_intr;
+ io_callbacks[j + 1] = out_intr;
+ io_names[j] = NULL;
+ io_names[j + 1] = NULL;
+ j += 2;
+ }
+ io_names[vq_num] = "serial-input";
+ io_names[vq_num + 1] = "serial-output";
+ err = portdev->vdev->config->find_vqs(portdev->vdev, nr_queues, vqs,
+ io_callbacks,
+ (const char **)io_names);
+ if (err)
+ goto free;
+ portdev->in_vqs[id] = vqs[vq_num];
+ portdev->out_vqs[id] = vqs[vq_num + 1];
I don't think this approach will work fine for port hot-plug /
hot-unplug cases at all. For example, I first start qemu with one
port, at id 1. Then I add a port at id 5, then at 2, then at 10.
Will that be fine?
yes.
In this case, the virtio-serial will create id 1's queue when probe the
device. Then, add port id 5, it will create the id 5's queue and the queues
of id 2-4 still be null.
we find the right ioport by vq_num, and only the io_name[vq_num] and
io_name[vq_num+1] are not null. So after portdev->vdev->config->find_vqs(),
the id 5's queues are created(see the changes in virtio-pci), the others
are
still null.
+
+free:
+ kfree(io_names);
+ kfree(io_callbacks);
+ kfree(vqs);
+
+ return err;
+}
+
static int add_port(struct ports_device *portdev, u32 id)
{
char debugfs_name[16];
@@ -1163,6 +1212,14 @@ static int add_port(struct ports_device *portdev, u32 id)
port->outvq_full = false;
+ if (!portdev->in_vqs[port->id]&& !portdev->out_vqs[port->id]) {
+ spin_lock(&portdev->ports_lock);
+ err = setup_port_vq(portdev, port->id);
+ spin_unlock(&portdev->ports_lock);
+ if (err)
+ goto free_port;
+ }
+
port->in_vq = portdev->in_vqs[port->id];
port->out_vq = portdev->out_vqs[port->id];
@@ -1614,8 +1671,8 @@ static int init_vqs(struct ports_device *portdev)
j += 2;
io_callbacks[j] = in_intr;
io_callbacks[j + 1] = out_intr;
- io_names[j] = "input";
- io_names[j + 1] = "output";
+ io_names[j] = NULL;
+ io_names[j + 1] = NULL;
}
}
/* Find the queues. */
@@ -1635,8 +1692,8 @@ static int init_vqs(struct ports_device *portdev)
for (i = 1; i< nr_ports; i++) {
j += 2;
- portdev->in_vqs[i] = vqs[j];
- portdev->out_vqs[i] = vqs[j + 1];
+ portdev->in_vqs[i] = NULL;
+ portdev->out_vqs[i] = NULL;
}
}
kfree(io_names);
So a queue once created will not be removed unless the module is
removed or the device is removed. That seems reasonable, port
hot-unplug will keep queues around, as is the case now.
As we use the virtio-serial with only a few io-ports, the maxport queues
may
waste more memory. So we try to create queues when port hot-plug, as for
port hot-unplug there's no change.
Amit
.
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