fix "modules: make module_address_lookup() safe"

Get the constness right, avoid nasty cast.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/module.h

@@ -449,7 +449,7 @@ static inline void __module_get(struct module *module)
 /* For kallsyms to ask for address resolution.  namebuf should be at
  * least KSYM_NAME_LEN long: a pointer to namebuf is returned if
  * found, otherwise NULL. */
-char *module_address_lookup(unsigned long addr,
+const char *module_address_lookup(unsigned long addr,
 			    unsigned long *symbolsize,
 			    unsigned long *offset,
 			    char **modname,
@@ -519,7 +519,7 @@ static inline void module_put(struct module *module)
 #define module_name(mod) "kernel"
 
 /* For kallsyms to ask for address resolution.  NULL means not found. */
-static inline char *module_address_lookup(unsigned long addr,
+static inline const char *module_address_lookup(unsigned long addr,
 					  unsigned long *symbolsize,
 					  unsigned long *offset,
 					  char **modname,

kernel/module.c

@@ -2253,7 +2253,7 @@ static const char *get_ksymbol(struct module *mod,
 
 /* For kallsyms to ask for address resolution.  NULL means not found.  Careful
  * not to lock to avoid deadlock on oopses, simply disable preemption. */
-char *module_address_lookup(unsigned long addr,
+const char *module_address_lookup(unsigned long addr,
 			    unsigned long *size,
 			    unsigned long *offset,
 			    char **modname,
@@ -2278,7 +2278,7 @@ char *module_address_lookup(unsigned long addr,
 		ret = namebuf;
 	}
 	preempt_enable();
-	return (char *)ret;
+	return ret;
 }
 
 int lookup_module_symbol_name(unsigned long addr, char *symname)