serial: earlycon: Skip parse_options() if empty string

Earlycon param strings of the form
   earlycon=<name>
are rejected from parse_options() with an error (which, in turn,
results in a NULL argument for the setup() method options parameter).

Only pass non-empty string to parse_options(); this will enable
handling actual parse errors differently than expected and allow
formats.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index da5e8c8c4ad4..025ea0140896 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -109,13 +109,16 @@ int __init setup_earlycon(char *buf, const char *match,
         len = strlen(match);
         if (strncmp(buf, match, len))
                 return 0;
-        if (buf[len] && (buf[len] != ','))
-                return 0;
 
-        buf += len + 1;
+        if (buf[len]) {
+                if (buf[len] != ',')
+                        return 0;
+                buf += len + 1;
+        } else
+                buf = NULL;
 
         /* On parsing error, pass the options buf to the setup function */
-        if (!parse_options(&early_console_dev, buf))
+        if (buf && !parse_options(&early_console_dev, buf))
                 buf = NULL;
 
         port->uartclk = BASE_BAUD * 16;