Fix race between cat /proc/slab_allocators and rmmod

Same story as with cat /proc/*/wchan race vs rmmod race, only
/proc/slab_allocators want more info than just symbol name.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 46 insertions, 0 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 4e2ec191a127..c36581b40c04 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -286,6 +286,25 @@ int lookup_symbol_name(unsigned long addr, char *symname)
 	return lookup_module_symbol_name(addr, symname);
 }
 
+int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
+			unsigned long *offset, char *modname, char *name)
+{
+	name[0] = '\0';
+	name[KSYM_NAME_LEN] = '\0';
+
+	if (is_ksym_addr(addr)) {
+		unsigned long pos;
+
+		pos = get_symbol_pos(addr, size, offset);
+		/* Grab name */
+		kallsyms_expand_symbol(get_symbol_offset(pos), name);
+		modname[0] = '\0';
+		return 0;
+	}
+	/* see if it's in a module */
+	return lookup_module_symbol_attrs(addr, size, offset, modname, name);
+}
+
 /* Look up a kernel symbol and return it in a text buffer. */
 int sprint_symbol(char *buffer, unsigned long address)
 {
diff --git a/kernel/module.c b/kernel/module.c
index 3da76ad32d78..d36e45477fac 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2149,6 +2149,33 @@ out:
 	return -ERANGE;
 }
 
+int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
+			unsigned long *offset, char *modname, char *name)
+{
+	struct module *mod;
+
+	mutex_lock(&module_mutex);
+	list_for_each_entry(mod, &modules, list) {
+		if (within(addr, mod->module_init, mod->init_size) ||
+		    within(addr, mod->module_core, mod->core_size)) {
+			const char *sym;
+
+			sym = get_ksymbol(mod, addr, size, offset);
+			if (!sym)
+				goto out;
+			if (modname)
+				strlcpy(modname, mod->name, MODULE_NAME_LEN + 1);
+			if (name)
+				strlcpy(name, sym, KSYM_NAME_LEN + 1);
+			mutex_unlock(&module_mutex);
+			return 0;
+		}
+	}
+out:
+	mutex_unlock(&module_mutex);
+	return -ERANGE;
+}
+
 int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 			char *name, char *module_name, int *exported)
 {