The problem comes when ks0108/cfag12864b are built-in and no parallel port is
present. ks0108_init() is called first, as it should be, but fails to load
(as there is no parallel port to use).
After that, cfag12864b_init() gets called, without knowing anything about
ks0108 failed, and calls ks0108_writecontrol(), which dereferences an
uninitialized pointer.
Init order is OK, I think. The problem is how to stop cfag12864b_init() being
called if ks0108 failed to load. modprobe does it for us, but, how when
built-in?
Signed-off-by: Miguel Ojeda Sandonis <maxextreme@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
EXPORT_SYMBOL_GPL(cfag12864b_isenabled);
/*
EXPORT_SYMBOL_GPL(cfag12864b_isenabled);
/*
+ * Is the module inited?
+ */
+
+static unsigned char cfag12864b_inited;
+unsigned char cfag12864b_isinited(void)
+{
+ return cfag12864b_inited;
+}
+EXPORT_SYMBOL_GPL(cfag12864b_isinited);
+
+/*
+ /* ks0108_init() must be called first */
+ if (!ks0108_isinited()) {
+ printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
+ "ks0108 is not initialized\n");
+ goto none;
+ }
+
if (PAGE_SIZE < CFAG12864B_SIZE) {
printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
"page size (%i) < cfag12864b size (%i)\n",
if (PAGE_SIZE < CFAG12864B_SIZE) {
printk(KERN_ERR CFAG12864B_NAME ": ERROR: "
"page size (%i) < cfag12864b size (%i)\n",
cfag12864b_clear();
cfag12864b_on();
cfag12864b_clear();
cfag12864b_on();
static int __init cfag12864bfb_init(void)
{
static int __init cfag12864bfb_init(void)
{
+ int ret = -EINVAL;
+
+ /* cfag12864b_init() must be called first */
+ if (!cfag12864b_isinited()) {
+ printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "
+ "cfag12864b is not initialized\n");
+ goto none;
+ }
if (cfag12864b_enable()) {
printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "
if (cfag12864b_enable()) {
printk(KERN_ERR CFAG12864BFB_NAME ": ERROR: "
EXPORT_SYMBOL_GPL(ks0108_page);
/*
EXPORT_SYMBOL_GPL(ks0108_page);
/*
+ * Is the module inited?
+ */
+
+static unsigned char ks0108_inited;
+unsigned char ks0108_isinited(void)
+{
+ return ks0108_inited;
+}
+EXPORT_SYMBOL_GPL(ks0108_isinited);
+
+/*
*/
extern unsigned char cfag12864b_isenabled(void);
*/
extern unsigned char cfag12864b_isenabled(void);
+/*
+ * Is the module inited?
+ */
+extern unsigned char cfag12864b_isinited(void);
+
#endif /* _CFAG12864B_H_ */
#endif /* _CFAG12864B_H_ */
/* Set the controller's current page (0..7) */
extern void ks0108_page(unsigned char page);
/* Set the controller's current page (0..7) */
extern void ks0108_page(unsigned char page);
+/* Is the module inited? */
+extern unsigned char ks0108_isinited(void);
+