powerpc/hvc_udbg: Don't crash when udbg_putc is NULL
Also while at it, add some help text indicating why you shouldn't
enable that driver under normal circumstances
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/tty/hvc/hvc_udbg.c b/drivers/tty/hvc/hvc_udbg.c
index b0957e6..2259c6e 100644
--- a/drivers/tty/hvc/hvc_udbg.c
+++ b/drivers/tty/hvc/hvc_udbg.c
@@ -36,7 +36,7 @@
{
int i;
- for (i = 0; i < count; i++)
+ for (i = 0; i < count && udbg_putc; i++)
udbg_putc(buf[i]);
return i;
@@ -67,6 +67,9 @@
{
struct hvc_struct *hp;
+ if (!udbg_putc)
+ return -ENODEV;
+
BUG_ON(hvc_udbg_dev);
hp = hvc_alloc(0, NO_IRQ, &hvc_udbg_ops, 16);
@@ -88,6 +91,9 @@
static int __init hvc_udbg_console_init(void)
{
+ if (!udbg_putc)
+ return -ENODEV;
+
hvc_instantiate(0, 0, &hvc_udbg_ops);
add_preferred_console("hvc", 0, NULL);