Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  module: fix bne2 "gave up waiting for init of module libcrc32c"
  module: verify_export_symbols under the lock
  module: move find_module check to end
  module: make locking more fine-grained.
  module: Make module sysfs functions private.
  module: move sysfs exposure to end of load_module
  module: fix kdb's illicit use of struct module_use.
  module: Make the 'usage' lists be two-way

2 files changed, 211 insertions, 121 deletions

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index b724c791b6d4..184cd8209c36 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1857,12 +1857,6 @@ static int kdb_ef(int argc, const char **argv)
 }
 
 #if defined(CONFIG_MODULES)
-/* modules using other modules */
-struct module_use {
-        struct list_head list;
-        struct module *module_which_uses;
-};
-
 /*
  * kdb_lsmod - This function implements the 'lsmod' command.  Lists
  *      currently loaded kernel modules.
@@ -1894,9 +1888,9 @@ static int kdb_lsmod(int argc, const char **argv)
                 {
                         struct module_use *use;
                         kdb_printf(" [ ");
-                        list_for_each_entry(use, &mod->modules_which_use_me,
-                                            list)
-                                kdb_printf("%s ", use->module_which_uses->name);
+                        list_for_each_entry(use, &mod->source_list,
+                                            source_list)
+                                kdb_printf("%s ", use->target->name);
                         kdb_printf("]\n");
                 }
 #endif
diff --git a/kernel/module.c b/kernel/module.c
index 0129769301e3..8c6b42840dd1 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -72,7 +72,11 @@
 /* If this is set, the section belongs in the init part of the module */
 #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
 
-/* List of modules, protected by module_mutex or preempt_disable
+/*
+ * Mutex protects:
+ * 1) List of modules (also safely readable with preempt_disable),
+ * 2) module_use links,
+ * 3) module_addr_min/module_addr_max.
  * (delete uses stop_machine/add uses RCU list operations). */
 DEFINE_MUTEX(module_mutex);
 EXPORT_SYMBOL_GPL(module_mutex);
@@ -90,7 +94,8 @@ static DECLARE_WAIT_QUEUE_HEAD(module_wq);
 
 static BLOCKING_NOTIFIER_HEAD(module_notify_list);
 
-/* Bounds of module allocation, for speeding __module_address */
+/* Bounds of module allocation, for speeding __module_address.
+ * Protected by module_mutex. */
 static unsigned long module_addr_min = -1UL, module_addr_max = 0;
 
 int register_module_notifier(struct notifier_block * nb)
@@ -329,7 +334,7 @@ static bool find_symbol_in_section(const struct symsearch *syms,
 }
 
 /* Find a symbol and return it, along with, (optional) crc and
- * (optional) module which owns it */
+ * (optional) module which owns it.  Needs preempt disabled or module_mutex. */
 const struct kernel_symbol *find_symbol(const char *name,
                                         struct module **owner,
                                         const unsigned long **crc,
@@ -523,7 +528,8 @@ static void module_unload_init(struct module *mod)
 {
         int cpu;
 
-        INIT_LIST_HEAD(&mod->modules_which_use_me);
+        INIT_LIST_HEAD(&mod->source_list);
+        INIT_LIST_HEAD(&mod->target_list);
         for_each_possible_cpu(cpu) {
                 per_cpu_ptr(mod->refptr, cpu)->incs = 0;
                 per_cpu_ptr(mod->refptr, cpu)->decs = 0;
@@ -535,20 +541,13 @@ static void module_unload_init(struct module *mod)
         mod->waiter = current;
 }
 
-/* modules using other modules */
-struct module_use
-{
-        struct list_head list;
-        struct module *module_which_uses;
-};
-
 /* Does a already use b? */
 static int already_uses(struct module *a, struct module *b)
 {
         struct module_use *use;
 
-        list_for_each_entry(use, &b->modules_which_use_me, list) {
-                if (use->module_which_uses == a) {
+        list_for_each_entry(use, &b->source_list, source_list) {
+                if (use->source == a) {
                         DEBUGP("%s uses %s!\n", a->name, b->name);
                         return 1;
                 }
@@ -557,62 +556,68 @@ static int already_uses(struct module *a, struct module *b)
         return 0;
 }
 
-/* Module a uses b */
-int use_module(struct module *a, struct module *b)
+/*
+ * Module a uses b
+ *  - we add 'a' as a "source", 'b' as a "target" of module use
+ *  - the module_use is added to the list of 'b' sources (so
+ *    'b' can walk the list to see who sourced them), and of 'a'
+ *    targets (so 'a' can see what modules it targets).
+ */
+static int add_module_usage(struct module *a, struct module *b)
 {
         struct module_use *use;
-        int no_warn, err;
 
-        if (b == NULL || already_uses(a, b)) return 1;
+        DEBUGP("Allocating new usage for %s.\n", a->name);
+        use = kmalloc(sizeof(*use), GFP_ATOMIC);
+        if (!use) {
+                printk(KERN_WARNING "%s: out of memory loading\n", a->name);
+                return -ENOMEM;
+        }
+
+        use->source = a;
+        use->target = b;
+        list_add(&use->source_list, &b->source_list);
+        list_add(&use->target_list, &a->target_list);
+        return 0;
+}
+
+/* Module a uses b: caller needs module_mutex() */
+int ref_module(struct module *a, struct module *b)
+{
+        int err;
 
-        /* If we're interrupted or time out, we fail. */
-        if (wait_event_interruptible_timeout(
-                    module_wq, (err = strong_try_module_get(b)) != -EBUSY,
-                    30 * HZ) <= 0) {
-                printk("%s: gave up waiting for init of module %s.\n",
-                       a->name, b->name);
+        if (b == NULL || already_uses(a, b))
                 return 0;
-        }
 
-        /* If strong_try_module_get() returned a different error, we fail. */
+        /* If module isn't available, we fail. */
+        err = strong_try_module_get(b);
         if (err)
-                return 0;
+                return err;
 
-        DEBUGP("Allocating new usage for %s.\n", a->name);
-        use = kmalloc(sizeof(*use), GFP_ATOMIC);
-        if (!use) {
-                printk("%s: out of memory loading\n", a->name);
+        err = add_module_usage(a, b);
+        if (err) {
                 module_put(b);
-                return 0;
+                return err;
         }
-
-        use->module_which_uses = a;
-        list_add(&use->list, &b->modules_which_use_me);
-        no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
-        return 1;
+        return 0;
 }
-EXPORT_SYMBOL_GPL(use_module);
+EXPORT_SYMBOL_GPL(ref_module);
 
 /* Clear the unload stuff of the module. */
 static void module_unload_free(struct module *mod)
 {
-        struct module *i;
+        struct module_use *use, *tmp;
 
-        list_for_each_entry(i, &modules, list) {
-                struct module_use *use;
-
-                list_for_each_entry(use, &i->modules_which_use_me, list) {
-                        if (use->module_which_uses == mod) {
-                                DEBUGP("%s unusing %s\n", mod->name, i->name);
-                                module_put(i);
-                                list_del(&use->list);
-                                kfree(use);
-                                sysfs_remove_link(i->holders_dir, mod->name);
-                                /* There can be at most one match. */
-                                break;
-                        }
-                }
+        mutex_lock(&module_mutex);
+        list_for_each_entry_safe(use, tmp, &mod->target_list, target_list) {
+                struct module *i = use->target;
+                DEBUGP("%s unusing %s\n", mod->name, i->name);
+                module_put(i);
+                list_del(&use->source_list);
+                list_del(&use->target_list);
+                kfree(use);
         }
+        mutex_unlock(&module_mutex);
 }
 
 #ifdef CONFIG_MODULE_FORCE_UNLOAD
@@ -735,7 +740,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                 goto out;
         }
 
-        if (!list_empty(&mod->modules_which_use_me)) {
+        if (!list_empty(&mod->source_list)) {
                 /* Other modules depend on us: get rid of them first. */
                 ret = -EWOULDBLOCK;
                 goto out;
@@ -779,13 +784,14 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
         blocking_notifier_call_chain(&module_notify_list,
                                      MODULE_STATE_GOING, mod);
         async_synchronize_full();
-        mutex_lock(&module_mutex);
+
         /* Store the name of the last unloaded module for diagnostic purposes */
         strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
         ddebug_remove_module(mod->name);
-        free_module(mod);
 
- out:
+        free_module(mod);
+        return 0;
+out:
         mutex_unlock(&module_mutex);
         return ret;
 }
@@ -799,9 +805,9 @@ static inline void print_unload_info(struct seq_file *m, struct module *mod)
 
         /* Always include a trailing , so userspace can differentiate
            between this and the old multi-field proc format. */
-        list_for_each_entry(use, &mod->modules_which_use_me, list) {
+        list_for_each_entry(use, &mod->source_list, source_list) {
                 printed_something = 1;
-                seq_printf(m, "%s,", use->module_which_uses->name);
+                seq_printf(m, "%s,", use->source->name);
         }
 
         if (mod->init != NULL && mod->exit == NULL) {
@@ -880,11 +886,11 @@ static inline void module_unload_free(struct module *mod)
 {
 }
 
-int use_module(struct module *a, struct module *b)
+int ref_module(struct module *a, struct module *b)
 {
-        return strong_try_module_get(b) == 0;
+        return strong_try_module_get(b);
 }
-EXPORT_SYMBOL_GPL(use_module);
+EXPORT_SYMBOL_GPL(ref_module);
 
 static inline void module_unload_init(struct module *mod)
 {
@@ -1001,6 +1007,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
 {
         const unsigned long *crc;
 
+        /* Since this should be found in kernel (which can't be removed),
+         * no locking is necessary. */
         if (!find_symbol(MODULE_SYMBOL_PREFIX "module_layout", NULL,
                          &crc, true, false))
                 BUG();
@@ -1043,29 +1051,62 @@ static inline int same_magic(const char *amagic, const char *bmagic,
 }
 #endif /* CONFIG_MODVERSIONS */
 
-/* Resolve a symbol for this module.  I.e. if we find one, record usage.
-   Must be holding module_mutex. */
+/* Resolve a symbol for this module.  I.e. if we find one, record usage. */
 static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs,
                                                   unsigned int versindex,
                                                   const char *name,
-                                                  struct module *mod)
+                                                  struct module *mod,
+                                                  char ownername[])
 {
         struct module *owner;
         const struct kernel_symbol *sym;
         const unsigned long *crc;
+        int err;
 
+        mutex_lock(&module_mutex);
         sym = find_symbol(name, &owner, &crc,
                           !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
-        /* use_module can fail due to OOM,
-           or module initialization or unloading */
-        if (sym) {
-                if (!check_version(sechdrs, versindex, name, mod, crc, owner)
-                    || !use_module(mod, owner))
-                        sym = NULL;
+        if (!sym)
+                goto unlock;
+
+        if (!check_version(sechdrs, versindex, name, mod, crc, owner)) {
+                sym = ERR_PTR(-EINVAL);
+                goto getname;
+        }
+
+        err = ref_module(mod, owner);
+        if (err) {
+                sym = ERR_PTR(err);
+                goto getname;
         }
+
+getname:
+        /* We must make copy under the lock if we failed to get ref. */
+        strncpy(ownername, module_name(owner), MODULE_NAME_LEN);
+unlock:
+        mutex_unlock(&module_mutex);
         return sym;
 }
 
+static const struct kernel_symbol *resolve_symbol_wait(Elf_Shdr *sechdrs,
+                                                       unsigned int versindex,
+                                                       const char *name,
+                                                       struct module *mod)
+{
+        const struct kernel_symbol *ksym;
+        char ownername[MODULE_NAME_LEN];
+
+        if (wait_event_interruptible_timeout(module_wq,
+                        !IS_ERR(ksym = resolve_symbol(sechdrs, versindex, name,
+                                                      mod, ownername)) ||
+                        PTR_ERR(ksym) != -EBUSY,
+                                             30 * HZ) <= 0) {
+                printk(KERN_WARNING "%s: gave up waiting for init of module %s.\n",
+                       mod->name, ownername);
+        }
+        return ksym;
+}
+
 /*
  * /sys/module/foo/sections stuff
  * J. Corbet <corbet@lwn.net>
@@ -1295,7 +1336,34 @@ static inline void remove_notes_attrs(struct module *mod)
 #endif
 
 #ifdef CONFIG_SYSFS
-int module_add_modinfo_attrs(struct module *mod)
+static void add_usage_links(struct module *mod)
+{
+#ifdef CONFIG_MODULE_UNLOAD
+        struct module_use *use;
+        int nowarn;
+
+        mutex_lock(&module_mutex);
+        list_for_each_entry(use, &mod->target_list, target_list) {
+                nowarn = sysfs_create_link(use->target->holders_dir,
+                                           &mod->mkobj.kobj, mod->name);
+        }
+        mutex_unlock(&module_mutex);
+#endif
+}
+
+static void del_usage_links(struct module *mod)
+{
+#ifdef CONFIG_MODULE_UNLOAD
+        struct module_use *use;
+
+        mutex_lock(&module_mutex);
+        list_for_each_entry(use, &mod->target_list, target_list)
+                sysfs_remove_link(use->target->holders_dir, mod->name);
+        mutex_unlock(&module_mutex);
+#endif
+}
+
+static int module_add_modinfo_attrs(struct module *mod)
 {
         struct module_attribute *attr;
         struct module_attribute *temp_attr;
@@ -1321,7 +1389,7 @@ int module_add_modinfo_attrs(struct module *mod)
         return error;
 }
 
-void module_remove_modinfo_attrs(struct module *mod)
+static void module_remove_modinfo_attrs(struct module *mod)
 {
         struct module_attribute *attr;
         int i;
@@ -1337,7 +1405,7 @@ void module_remove_modinfo_attrs(struct module *mod)
         kfree(mod->modinfo_attrs);
 }
 
-int mod_sysfs_init(struct module *mod)
+static int mod_sysfs_init(struct module *mod)
 {
         int err;
         struct kobject *kobj;
@@ -1371,12 +1439,16 @@ out:
         return err;
 }
 
-int mod_sysfs_setup(struct module *mod,
+static int mod_sysfs_setup(struct module *mod,
                            struct kernel_param *kparam,
                            unsigned int num_params)
 {
         int err;
 
+        err = mod_sysfs_init(mod);
+        if (err)
+                goto out;
+
         mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj);
         if (!mod->holders_dir) {
                 err = -ENOMEM;
@@ -1391,6 +1463,8 @@ int mod_sysfs_setup(struct module *mod,
         if (err)
                 goto out_unreg_param;
 
+        add_usage_links(mod);
+
         kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);
         return 0;
 
@@ -1400,6 +1474,7 @@ out_unreg_holders:
         kobject_put(mod->holders_dir);
 out_unreg:
         kobject_put(&mod->mkobj.kobj);
+out:
         return err;
 }
 
@@ -1410,14 +1485,40 @@ static void mod_sysfs_fini(struct module *mod)
 
 #else /* CONFIG_SYSFS */
 
+static inline int mod_sysfs_init(struct module *mod)
+{
+        return 0;
+}
+
+static inline int mod_sysfs_setup(struct module *mod,
+                           struct kernel_param *kparam,
+                           unsigned int num_params)
+{
+        return 0;
+}
+
+static inline int module_add_modinfo_attrs(struct module *mod)
+{
+        return 0;
+}
+
+static inline void module_remove_modinfo_attrs(struct module *mod)
+{
+}
+
 static void mod_sysfs_fini(struct module *mod)
 {
 }
 
+static void del_usage_links(struct module *mod)
+{
+}
+
 #endif /* CONFIG_SYSFS */
 
 static void mod_kobject_remove(struct module *mod)
 {
+        del_usage_links(mod);
         module_remove_modinfo_attrs(mod);
         module_param_sysfs_remove(mod);
         kobject_put(mod->mkobj.drivers_dir);
@@ -1436,13 +1537,15 @@ static int __unlink_module(void *_mod)
         return 0;
 }
 
-/* Free a module, remove from lists, etc (must hold module_mutex). */
+/* Free a module, remove from lists, etc. */
 static void free_module(struct module *mod)
 {
         trace_module_free(mod);
 
         /* Delete from various lists */
+        mutex_lock(&module_mutex);
         stop_machine(__unlink_module, mod, NULL);
+        mutex_unlock(&module_mutex);
         remove_notes_attrs(mod);
         remove_sect_attrs(mod);
         mod_kobject_remove(mod);
@@ -1493,6 +1596,8 @@ EXPORT_SYMBOL_GPL(__symbol_get);
 /*
  * Ensure that an exported symbol [global namespace] does not already exist
  * in the kernel or in some other module's exported symbol table.
+ *
+ * You must hold the module_mutex.
  */
 static int verify_export_symbols(struct module *mod)
 {
@@ -1558,21 +1663,23 @@ static int simplify_symbols(Elf_Shdr *sechdrs,
                         break;
 
                 case SHN_UNDEF:
-                        ksym = resolve_symbol(sechdrs, versindex,
-                                              strtab + sym[i].st_name, mod);
+                        ksym = resolve_symbol_wait(sechdrs, versindex,
+                                                   strtab + sym[i].st_name,
+                                                   mod);
                         /* Ok if resolved.  */
-                        if (ksym) {
+                        if (ksym && !IS_ERR(ksym)) {
                                 sym[i].st_value = ksym->value;
                                 break;
                         }
 
                         /* Ok if weak.  */
-                        if (ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
+                        if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
                                 break;
 
-                        printk(KERN_WARNING "%s: Unknown symbol %s\n",
-                               mod->name, strtab + sym[i].st_name);
-                        ret = -ENOENT;
+                        printk(KERN_WARNING "%s: Unknown symbol %s (err %li)\n",
+                               mod->name, strtab + sym[i].st_name,
+                               PTR_ERR(ksym));
+                        ret = PTR_ERR(ksym) ?: -ENOENT;
                         break;
 
                 default:
@@ -1960,11 +2067,13 @@ static void *module_alloc_update_bounds(unsigned long size)
         void *ret = module_alloc(size);
 
         if (ret) {
+                mutex_lock(&module_mutex);
                 /* Update module bounds. */
                 if ((unsigned long)ret < module_addr_min)
                         module_addr_min = (unsigned long)ret;
                 if ((unsigned long)ret + size > module_addr_max)
                         module_addr_max = (unsigned long)ret + size;
+                mutex_unlock(&module_mutex);
         }
         return ret;
 }
@@ -2139,11 +2248,6 @@ static noinline struct module *load_module(void __user *umod,
                 goto free_mod;
         }
 
-        if (find_module(mod->name)) {
-                err = -EEXIST;
-                goto free_mod;
-        }
-
         mod->state = MODULE_STATE_COMING;
 
         /* Allow arches to frob section contents and sizes.  */
@@ -2234,11 +2338,6 @@ static noinline struct module *load_module(void __user *umod,
         /* Now we've moved module, initialize linked lists, etc. */
         module_unload_init(mod);
 
-        /* add kobject, so we can reference it. */
-        err = mod_sysfs_init(mod);
-        if (err)
-                goto free_unload;
-
         /* Set up license info based on the info section */
         set_license(mod, get_modinfo(sechdrs, infoindex, "license"));
 
@@ -2363,11 +2462,6 @@ static noinline struct module *load_module(void __user *umod,
                         goto cleanup;
         }
 
-        /* Find duplicate symbols */
-        err = verify_export_symbols(mod);
-        if (err < 0)
-                goto cleanup;
-
         /* Set up and sort exception table */
         mod->extable = section_objs(hdr, sechdrs, secstrings, "__ex_table",
                                     sizeof(*mod->extable), &mod->num_exentries);
@@ -2426,7 +2520,19 @@ static noinline struct module *load_module(void __user *umod,
          * function to insert in a way safe to concurrent readers.
          * The mutex protects against concurrent writers.
          */
+        mutex_lock(&module_mutex);
+        if (find_module(mod->name)) {
+                err = -EEXIST;
+                goto unlock;
+        }
+
+        /* Find duplicate symbols */
+        err = verify_export_symbols(mod);
+        if (err < 0)
+                goto unlock;
+
         list_add_rcu(&mod->list, &modules);
+        mutex_unlock(&module_mutex);
 
         err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, NULL);
         if (err < 0)
@@ -2435,6 +2541,7 @@ static noinline struct module *load_module(void __user *umod,
         err = mod_sysfs_setup(mod, mod->kp, mod->num_kp);
         if (err < 0)
                 goto unlink;
+
         add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
         add_notes_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
 
@@ -2447,15 +2554,15 @@ static noinline struct module *load_module(void __user *umod,
         return mod;
 
  unlink:
+        mutex_lock(&module_mutex);
         /* Unlink carefully: kallsyms could be walking list. */
         list_del_rcu(&mod->list);
+ unlock:
+        mutex_unlock(&module_mutex);
         synchronize_sched();
         module_arch_cleanup(mod);
  cleanup:
         free_modinfo(mod);
-        kobject_del(&mod->mkobj.kobj);
-        kobject_put(&mod->mkobj.kobj);
- free_unload:
         module_unload_free(mod);
 #if defined(CONFIG_MODULE_UNLOAD)
         free_percpu(mod->refptr);
@@ -2502,19 +2609,10 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
         if (!capable(CAP_SYS_MODULE) || modules_disabled)
                 return -EPERM;
 
-        /* Only one module load at a time, please */
-        if (mutex_lock_interruptible(&module_mutex) != 0)
-                return -EINTR;
-
         /* Do all the hard work */
         mod = load_module(umod, len, uargs);
-        if (IS_ERR(mod)) {
-                mutex_unlock(&module_mutex);
+        if (IS_ERR(mod))
                 return PTR_ERR(mod);
-        }
-
-        /* Drop lock so they can recurse */
-        mutex_unlock(&module_mutex);
 
         blocking_notifier_call_chain(&module_notify_list,
                         MODULE_STATE_COMING, mod);
@@ -2531,9 +2629,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
                 module_put(mod);
                 blocking_notifier_call_chain(&module_notify_list,
                                              MODULE_STATE_GOING, mod);
-                mutex_lock(&module_mutex);
                 free_module(mod);
-                mutex_unlock(&module_mutex);
                 wake_up(&module_wq);
                 return ret;
         }