module: struct module_ref should contains long fields

module_ref contains two "unsigned int" fields.

Thats now too small, since some machines can open more than 2^32 files.

Check commit 518de9b39e8 (fs: allow for more than 2^31 files) for
reference.

We can add an aligned(2 * sizeof(unsigned long)) attribute to force
alloc_percpu() allocating module_ref areas in single cache lines.

Signed-off-by: Eric Dumazet <[e-mail]>
CC: Rusty Russell <[e-mail]>
CC: Tejun Heo <[e-mail]>
CC: Robin Holt <[e-mail]>
CC: David Miller <[e-mail]>
Signed-off-by: Rusty Russell <[e-mail]>

include/linux/module.h

···
 	MODULE_STATE_GOING,
 };
 
+/**
+ * struct module_ref - per cpu module reference counts
+ * @incs: number of module get on this cpu
+ * @decs: number of module put on this cpu
+ *
+ * We force an alignment on 8 or 16 bytes, so that alloc_percpu()
+ * put @incs/@decs in same cache line, with no extra memory cost,
+ * since alloc_percpu() is fine grained.
+ */
+struct module_ref {
+	unsigned long incs;
+	unsigned long decs;
+} __attribute((aligned(2 * sizeof(unsigned long))));
+
 struct module
 {
 	enum module_state state;
···
 	/* Destruction function. */
 	void (*exit)(void);
 
-	struct module_ref {
-		unsigned int incs;
-		unsigned int decs;
-	} __percpu *refptr;
+	struct module_ref __percpu *refptr;
 #endif
 
 #ifdef CONFIG_CONSTRUCTORS
···
 #define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code);
 
 #ifdef CONFIG_MODULE_UNLOAD
-unsigned int module_refcount(struct module *mod);
+unsigned long module_refcount(struct module *mod);
 void __symbol_put(const char *symbol);
 #define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x)
 void symbol_put_addr(void *addr);

kernel/debug/kdb/kdb_main.c

···
 		kdb_printf("%-20s%8u  0x%p ", mod->name,
 			   mod->core_size, (void *)mod);
 #ifdef CONFIG_MODULE_UNLOAD
-		kdb_printf("%4d ", module_refcount(mod));
+		kdb_printf("%4ld ", module_refcount(mod));
 #endif
 		if (mod->state == MODULE_STATE_GOING)
 			kdb_printf(" (Unloading)");

kernel/module.c

···
 	}
 }
 
-unsigned int module_refcount(struct module *mod)
+unsigned long module_refcount(struct module *mod)
 {
-	unsigned int incs = 0, decs = 0;
+	unsigned long incs = 0, decs = 0;
 	int cpu;
 
 	for_each_possible_cpu(cpu)
···
 	struct module_use *use;
 	int printed_something = 0;
 
-	seq_printf(m, " %u ", module_refcount(mod));
+	seq_printf(m, " %lu ", module_refcount(mod));
 
 	/* Always include a trailing , so userspace can differentiate
            between this and the old multi-field proc format. */
···
 static ssize_t show_refcnt(struct module_attribute *mattr,
 			   struct module_kobject *mk, char *buffer)
 {
-	return sprintf(buffer, "%u\n", module_refcount(mk->mod));
+	return sprintf(buffer, "%lu\n", module_refcount(mk->mod));
 }
 
 static struct module_attribute refcnt = {