braille-console: Fix value returned by _braille_console_setup

commit bbeddf52adc1 ("printk: move braille console support into
separate braille.[ch] files") introduced _braille_console_setup()
to outline the braille initialization code.  There was however some
confusion over the value it was supposed to return. commit 2cfe6c4ac7ee
("printk: Fix return of braille_register_console()") tried to fix it
but failed to.

This fixes and documents the returned value according to the use
in printk.c: non-zero return means a parsing error, and thus this
console configuration should be ignored.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Aleksey Makarov <aleksey.makarov@linaro.org>
Cc: Joe Perches <joe@perches.com>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 18 insertions, 10 deletions

diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c
index d5760c42f042..61d41ca41844 100644
--- a/kernel/printk/braille.c
+++ b/kernel/printk/braille.c
@@ -2,12 +2,13 @@
 
 #include <linux/kernel.h>
 #include <linux/console.h>
+#include <linux/errno.h>
 #include <linux/string.h>
 
 #include "console_cmdline.h"
 #include "braille.h"
 
-char *_braille_console_setup(char **str, char **brl_options)
+int _braille_console_setup(char **str, char **brl_options)
 {
         if (!strncmp(*str, "brl,", 4)) {
                 *brl_options = "";
@@ -15,14 +16,14 @@ char *_braille_console_setup(char **str, char **brl_options)
         } else if (!strncmp(*str, "brl=", 4)) {
                 *brl_options = *str + 4;
                 *str = strchr(*brl_options, ',');
-                if (!*str)
+                if (!*str) {
                         pr_err("need port name after brl=\n");
-                else
-                        *((*str)++) = 0;
-        } else
-                return NULL;
+                        return -EINVAL;
+                }
+                *((*str)++) = 0;
+        }
 
-        return *str;
+        return 0;
 }
 
 int
diff --git a/kernel/printk/braille.h b/kernel/printk/braille.h
index 769d771145c8..749a6756843a 100644
--- a/kernel/printk/braille.h
+++ b/kernel/printk/braille.h
@@ -9,7 +9,14 @@ braille_set_options(struct console_cmdline *c, char *brl_options)
         c->brl_options = brl_options;
 }
 
-char *
+/*
+ * Setup console according to braille options.
+ * Return -EINVAL on syntax error, 0 on success (or no braille option was
+ * actually given).
+ * Modifies str to point to the serial options
+ * Sets brl_options to the parsed braille options.
+ */
+int
 _braille_console_setup(char **str, char **brl_options);
 
 int
@@ -25,10 +32,10 @@ braille_set_options(struct console_cmdline *c, char *brl_options)
 {
 }
 
-static inline char *
+static inline int
 _braille_console_setup(char **str, char **brl_options)
 {
-        return NULL;
+        return 0;
 }
 
 static inline int