Simplify kallsyms_lookup()

Several kallsyms_lookup() pass dummy arguments but only need, say, module's
name.  Make kallsyms_lookup() accept NULLs where possible.

Also, makes picture clearer about what interfaces are needed for all symbol
resolving business.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a3e77fb..3b4fe21 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -278,14 +278,13 @@
  */
 static int proc_pid_wchan(struct task_struct *task, char *buffer)
 {
-	char *modname;
 	const char *sym_name;
-	unsigned long wchan, size, offset;
+	unsigned long wchan;
 	char namebuf[KSYM_NAME_LEN+1];
 
 	wchan = get_wchan(task);
 
-	sym_name = kallsyms_lookup(wchan, &size, &offset, &modname, namebuf);
+	sym_name = kallsyms_lookup(wchan, NULL, NULL, NULL, namebuf);
 	if (sym_name)
 		return sprintf(buffer, "%s", sym_name);
 	return sprintf(buffer, "%lu", wchan);