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>

10 files changed, 20 insertions, 28 deletions

diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c
index 5f75b3e65986..89c03707eccc 100644
--- a/arch/parisc/kernel/unwind.c
+++ b/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);
 
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index b481db1dacb4..28fdf4f50c27 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/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;
diff --git a/arch/sh64/kernel/unwind.c b/arch/sh64/kernel/unwind.c
index f934f97f9f9c..1214c78e3584 100644
--- a/arch/sh64/kernel/unwind.c
+++ b/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;
 
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a3e77fb867ea..3b4fe21c7e94 100644
--- a/fs/proc/base.c
+++ b/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);
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index f1ea6f66ac6c..f66da025cb7f 100644
--- a/kernel/kallsyms.c
+++ b/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;
 }
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 0207045b4f6f..bee29bde6adf 100644
--- a/kernel/kprobes.c
+++ b/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)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index c1e308a080b8..7f573136a905 100644
--- a/kernel/lockdep.c
+++ b/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
diff --git a/kernel/module.c b/kernel/module.c
index 5ee65994a3bc..bf4dccadf7b8 100644
--- a/kernel/module.c
+++ b/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;
 }
 
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 59df5e8555a8..fe9314a89f20 100644
--- a/kernel/time/timer_list.c
+++ b/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
diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
index 1bc4882e28e0..946ed45f7d2f 100644
--- a/kernel/time/timer_stats.c
+++ b/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