On (Thu) Oct 01 2009 [11:00:48], Christian Borntraeger wrote:
> Am Mittwoch 30 September 2009 19:13:21 schrieb Amit Shah:
> > - uses port->id instead of a static hvc_vtermno to pass on a value to
> > hvc_alloc(). Motivation explained within comments in the code.
>
> [...]
> > + * The first argument of hvc_alloc() is the virtual console
> > + * number. hvc_alloc() checks if a console with the same value
> > + * was used in hvc_instantiate(). We may not end up passing
> > + * the same value here (we use the value 0 in
> > + * hvc_instantiate() but the console port may not be at id
> > + * 0). This isn't a problem, though. Nothing in hvc really
> > + * depends on these numbers and since this number is passed on
> > + * to us when cons_get/put_chars() is called, it's preferable
> > + * to pass on the port->id so that we can get the port struct
> > + * via get_port_from_id().
> [...]
> > + port->hvc = hvc_alloc(port->id, 0, &virtio_cons, PAGE_SIZE);
>
> I am not sure if this is going to be ok.
>
> When I change the old code (without your patch) to use vtermno=0 in
> hvc_instantiate and vtermno=1 in hvc_alloc I get
> "Warning: unable to open an initial console."
>
> It seems to me that we have to pass the same values.
OK; that's bad enough. The following diff reverts that patch and adds a
new get_port_from_vtermno() that works from hvc callbacks.
What do you think? (Applies on top of the latest patch I sent.)
Amit
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index b2de2df..a8ba5aa 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -105,12 +105,42 @@ struct virtio_console_port {
/* The 'id' to identify the port with the Host */
u32 id;
+ /*
+ * If this port is a console port, this number identifies the
+ * number that we used to register with hvc in
+ * hvc_instantiate() and hvc_alloc().
+ */
+ u32 vtermno;
+
/* Is the host device open */
bool host_connected;
};
static struct virtio_console_struct virtconsole;
+/*
+ * This is used to keep track of the number of hvc consoles spawned.
+ * This number is given as first argument to hvc_alloc(). We could as
+ * well pass on the minor number of the char device but to correctly
+ * map an initial console spawned via hvc_instantiate to the console
+ * being hooked up via hvc_alloc, we need to pass the same vtermno.
+ *
+ * With this int, we just assume the first console being initialised
+ * was the first one that got used as the initial console.
+ */
+static unsigned int hvc_vtermno;
+
+static struct virtio_console_port *get_port_from_vtermno(u32 vtermno)
+{
+ struct virtio_console_port *port;
+
+ list_for_each_entry(port, &virtconsole.port_head, next) {
+ if (port->vtermno == vtermno)
+ return port;
+ }
+ return NULL;
+}
+
static struct virtio_console_port *get_port_from_devt(dev_t devt)
{
struct virtio_console_port *port;
@@ -457,7 +487,7 @@ static int cons_put_chars(u32 vtermno, const char *buf, int count)
{
struct virtio_console_port *port;
- port = get_port_from_id(vtermno);
+ port = get_port_from_vtermno(vtermno);
if (!port)
return 0;
@@ -478,7 +508,7 @@ static int cons_get_chars(u32 vtermno, char *buf, int count)
/* If we don't have an input queue yet, we can't get input. */
BUG_ON(!virtconsole.in_vq);
- port = get_port_from_id(vtermno);
+ port = get_port_from_vtermno(vtermno);
if (!port)
return 0;
@@ -566,32 +596,23 @@ int init_port_console(struct virtio_console_port *port)
* hvc_alloc().
*
* The first argument of hvc_alloc() is the virtual console
- * number. hvc_alloc() checks if a console with the same value
- * was used in hvc_instantiate(). We may not end up passing
- * the same value here (we use the value 0 in
- * hvc_instantiate() but the console port may not be at id
- * 0). This isn't a problem, though. Nothing in hvc really
- * depends on these numbers and since this number is passed on
- * to us when cons_get/put_chars() is called, it's preferable
- * to pass on the port->id so that we can get the port struct
- * via get_port_from_id().
- *
- * The second argument is the parameter for the notification
- * mechanism (like irq number). We currently leave this as
- * zero, virtqueues have implicit notifications.
+ * number. The second argument is the parameter for the
+ * notification mechanism (like irq number). We currently
+ * leave this as zero, virtqueues have implicit notifications.
*
* The third argument is a "struct hv_ops" containing the
* put_chars() get_chars(), notifier_add() and notifier_del()
* pointers. The final argument is the output buffer size: we
* can do any size, so we put PAGE_SIZE here.
*/
- port->hvc = hvc_alloc(port->id, 0, &virtio_cons, PAGE_SIZE);
+ port->hvc = hvc_alloc(hvc_vtermno, 0, &virtio_cons, PAGE_SIZE);
if (IS_ERR(port->hvc)) {
ret = PTR_ERR(port->hvc);
pr_err("%s: Could not alloc hvc for virtio console port, ret = %d\n",
__func__, ret);
port->hvc = NULL;
}
+ port->vtermno = hvc_vtermno++;
return ret;
}
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