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>

arch/parisc/kernel/unwind.c

@@ -216,11 +216,8 @@ static void unwind_frame_regs(struct unwind_frame_info *info)
 		/* Handle some frequent special cases.... */
 		{
 			char symname[KSYM_NAME_LEN+1];
-			char *modname;
-			unsigned long symsize, offset;
 
-			kallsyms_lookup(info->ip, &symsize, &offset,
-					&modname, symname);
+			kallsyms_lookup(info->ip, NULL, NULL, NULL, symname);
 
 			dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname);
 

arch/powerpc/xmon/xmon.c

@@ -1217,7 +1217,6 @@ static void get_function_bounds(unsigned long pc, unsigned long *startp,
 {
 	unsigned long size, offset;
 	const char *name;
-	char *modname;
 
 	*startp = *endp = 0;
 	if (pc == 0)
@@ -1225,7 +1224,7 @@ static void get_function_bounds(unsigned long pc, unsigned long *startp,
 	if (setjmp(bus_error_jmp) == 0) {
 		catch_memory_errors = 1;
 		sync();
-		name = kallsyms_lookup(pc, &size, &offset, &modname, tmpstr);
+		name = kallsyms_lookup(pc, &size, &offset, NULL, tmpstr);
 		if (name != NULL) {
 			*startp = pc - offset;
 			*endp = pc - offset + size;

arch/sh64/kernel/unwind.c

@@ -46,15 +46,15 @@ static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
 		      struct pt_regs *regs)
 {
 	const char *sym;
-	char *modname, namebuf[128];
-	unsigned long offset, size;
+	char namebuf[128];
+	unsigned long offset;
 	unsigned long prologue = 0;
 	unsigned long fp_displacement = 0;
 	unsigned long fp_prev = 0;
 	unsigned long offset_r14 = 0, offset_r18 = 0;
 	int i, found_prologue_end = 0;
 
-	sym = kallsyms_lookup(pc, &size, &offset, &modname, namebuf);
+	sym = kallsyms_lookup(pc, NULL, &offset, NULL, namebuf);
 	if (!sym)
 		return -EINVAL;
 

fs/proc/base.c

@@ -278,14 +278,13 @@ static int proc_pid_auxv(struct task_struct *task, char *buffer)
  */
 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);

kernel/kallsyms.c

@@ -214,8 +214,10 @@ static unsigned long get_symbol_pos(unsigned long addr,
 			symbol_end = (unsigned long)_etext;
 	}
 
-	*symbolsize = symbol_end - symbol_start;
-	*offset = addr - symbol_start;
+	if (symbolsize)
+		*symbolsize = symbol_end - symbol_start;
+	if (offset)
+		*offset = addr - symbol_start;
 
 	return low;
 }

kernel/kprobes.c

@@ -868,13 +868,13 @@ static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
 	struct kprobe *p, *kp;
 	const char *sym = NULL;
 	unsigned int i = *(loff_t *) v;
-	unsigned long size, offset = 0;
+	unsigned long offset = 0;
 	char *modname, namebuf[128];
 
 	head = &kprobe_table[i];
 	preempt_disable();
 	hlist_for_each_entry_rcu(p, node, head, hlist) {
-		sym = kallsyms_lookup((unsigned long)p->addr, &size,
+		sym = kallsyms_lookup((unsigned long)p->addr, NULL,
 					&offset, &modname, namebuf);
 		if (p->pre_handler == aggr_pre_handler) {
 			list_for_each_entry_rcu(kp, &p->list, list)

kernel/lockdep.c

@@ -340,10 +340,7 @@ static const char *usage_str[] =
 
 const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
 {
-	unsigned long offs, size;
-	char *modname;
-
-	return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str);
+	return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
 }
 
 void

kernel/module.c

@@ -2098,8 +2098,10 @@ static const char *get_ksymbol(struct module *mod,
 	if (!best)
 		return NULL;
 
-	*size = nextval - mod->symtab[best].st_value;
-	*offset = addr - mod->symtab[best].st_value;
+	if (size)
+		*size = nextval - mod->symtab[best].st_value;
+	if (offset)
+		*offset = addr - mod->symtab[best].st_value;
 	return mod->strtab + mod->symtab[best].st_name;
 }
 

kernel/time/timer_list.c

@@ -40,11 +40,9 @@ static void print_name_offset(struct seq_file *m, void *sym)
 {
 	unsigned long addr = (unsigned long)sym;
 	char namebuf[KSYM_NAME_LEN+1];
-	unsigned long size, offset;
 	const char *sym_name;
-	char *modname;
 
-	sym_name = kallsyms_lookup(addr, &size, &offset, &modname, namebuf);
+	sym_name = kallsyms_lookup(addr, NULL, NULL, NULL, namebuf);
 	if (sym_name)
 		SEQ_printf(m, "%s", sym_name);
 	else

kernel/time/timer_stats.c

@@ -258,11 +258,9 @@ void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
 static void print_name_offset(struct seq_file *m, unsigned long addr)
 {
 	char namebuf[KSYM_NAME_LEN+1];
-	unsigned long size, offset;
 	const char *sym_name;
-	char *modname;
 
-	sym_name = kallsyms_lookup(addr, &size, &offset, &modname, namebuf);
+	sym_name = kallsyms_lookup(addr, NULL, NULL, NULL, namebuf);
 	if (sym_name)
 		seq_printf(m, "%s", sym_name);
 	else