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path: root/drivers/char/hvc_vio.c
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Diffstat (limited to 'drivers/char/hvc_vio.c')
-rw-r--r--drivers/char/hvc_vio.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/char/hvc_vio.c b/drivers/char/hvc_vio.c
index f5212eb2b41d..9add81ceb440 100644
--- a/drivers/char/hvc_vio.c
+++ b/drivers/char/hvc_vio.c
@@ -31,10 +31,13 @@
#include <linux/types.h>
#include <linux/init.h>
+
#include <asm/hvconsole.h>
#include <asm/vio.h>
#include <asm/prom.h>
+#include "hvc_console.h"
+
char hvc_driver_name[] = "hvc_console";
static struct vio_device_id hvc_driver_table[] __devinitdata = {
@@ -48,6 +51,14 @@ static int filtered_get_chars(uint32_t vtermno, char *buf, int count)
unsigned long got;
int i;
+ /*
+ * Vio firmware will read up to SIZE_VIO_GET_CHARS at its own discretion
+ * so we play safe and avoid the situation where got > count which could
+ * overload the flip buffer.
+ */
+ if (count < SIZE_VIO_GET_CHARS)
+ return -EAGAIN;
+
got = hvc_get_chars(vtermno, buf, count);
/*