diff options
Diffstat (limited to 'kernel/module.c')
| -rw-r--r-- | kernel/module.c | 181 |
1 files changed, 133 insertions, 48 deletions
diff --git a/kernel/module.c b/kernel/module.c index 250092c..eab0827 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -188,6 +188,7 @@ struct load_info { ongoing or failed initialization etc. */ static inline int strong_try_module_get(struct module *mod) { + BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED); if (mod && mod->state == MODULE_STATE_COMING) return -EBUSY; if (try_module_get(mod)) @@ -343,6 +344,9 @@ bool each_symbol_section(bool (*fn)(const struct symsearch *arr, #endif }; + if (mod->state == MODULE_STATE_UNFORMED) + continue; + if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data)) return true; } @@ -450,16 +454,24 @@ const struct kernel_symbol *find_symbol(const char *name, EXPORT_SYMBOL_GPL(find_symbol); /* Search for module by name: must hold module_mutex. */ -struct module *find_module(const char *name) +static struct module *find_module_all(const char *name, + bool even_unformed) { struct module *mod; list_for_each_entry(mod, &modules, list) { + if (!even_unformed && mod->state == MODULE_STATE_UNFORMED) + continue; if (strcmp(mod->name, name) == 0) return mod; } return NULL; } + +struct module *find_module(const char *name) +{ + return find_module_all(name, false); +} EXPORT_SYMBOL_GPL(find_module); #ifdef CONFIG_SMP @@ -525,6 +537,8 @@ bool is_module_percpu_address(unsigned long addr) preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (!mod->percpu_size) continue; for_each_possible_cpu(cpu) { @@ -1048,6 +1062,8 @@ static ssize_t show_initstate(struct module_attribute *mattr, case MODULE_STATE_GOING: state = "going"; break; + default: + BUG(); } return sprintf(buffer, "%s\n", state); } @@ -1786,6 +1802,8 @@ void set_all_modules_text_rw(void) mutex_lock(&module_mutex); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if ((mod->module_core) && (mod->core_text_size)) { set_page_attributes(mod->module_core, mod->module_core + mod->core_text_size, @@ -1807,6 +1825,8 @@ void set_all_modules_text_ro(void) mutex_lock(&module_mutex); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if ((mod->module_core) && (mod->core_text_size)) { set_page_attributes(mod->module_core, mod->module_core + mod->core_text_size, @@ -2527,6 +2547,13 @@ static int copy_module_from_fd(int fd, struct load_info *info) err = -EFBIG; goto out; } + + /* Don't hand 0 to vmalloc, it whines. */ + if (stat.size == 0) { + err = -EINVAL; + goto out; + } + info->hdr = vmalloc(stat.size); if (!info->hdr) { err = -ENOMEM; @@ -2990,8 +3017,9 @@ static bool finished_loading(const char *name) bool ret; mutex_lock(&module_mutex); - mod = find_module(name); - ret = !mod || mod->state != MODULE_STATE_COMING; + mod = find_module_all(name, true); + ret = !mod || mod->state == MODULE_STATE_LIVE + || mod->state == MODULE_STATE_GOING; mutex_unlock(&module_mutex); return ret; @@ -3013,6 +3041,12 @@ static int do_init_module(struct module *mod) { int ret = 0; + /* + * We want to find out whether @mod uses async during init. Clear + * PF_USED_ASYNC. async_schedule*() will set it. + */ + current->flags &= ~PF_USED_ASYNC; + blocking_notifier_call_chain(&module_notify_list, MODULE_STATE_COMING, mod); @@ -3058,8 +3092,25 @@ static int do_init_module(struct module *mod) blocking_notifier_call_chain(&module_notify_list, MODULE_STATE_LIVE, mod); - /* We need to finish all async code before the module init sequence is done */ - async_synchronize_full(); + /* + * We need to finish all async code before the module init sequence + * is done. This has potential to deadlock. For example, a newly + * detected block device can trigger request_module() of the + * default iosched from async probing task. Once userland helper + * reaches here, async_synchronize_full() will wait on the async + * task waiting on request_module() and deadlock. + * + * This deadlock is avoided by perfomring async_synchronize_full() + * iff module init queued any async jobs. This isn't a full + * solution as it will deadlock the same if module loading from + * async jobs nests more than once; however, due to the various + * constraints, this hack seems to be the best option for now. + * Please refer to the following thread for details. + * + * http://thread.gmane.org/gmane.linux.kernel/1420814 + */ + if (current->flags & PF_USED_ASYNC) + async_synchronize_full(); mutex_lock(&module_mutex); /* Drop initial reference. */ @@ -3113,6 +3164,32 @@ static int load_module(struct load_info *info, const char __user *uargs, goto free_copy; } + /* + * We try to place it in the list now to make sure it's unique + * before we dedicate too many resources. In particular, + * temporary percpu memory exhaustion. + */ + mod->state = MODULE_STATE_UNFORMED; +again: + mutex_lock(&module_mutex); + if ((old = find_module_all(mod->name, true)) != NULL) { + if (old->state == MODULE_STATE_COMING + || old->state == MODULE_STATE_UNFORMED) { + /* Wait in case it fails to load. */ + mutex_unlock(&module_mutex); + err = wait_event_interruptible(module_wq, + finished_loading(mod->name)); + if (err) + goto free_module; + goto again; + } + err = -EEXIST; + mutex_unlock(&module_mutex); + goto free_module; + } + list_add_rcu(&mod->list, &modules); + mutex_unlock(&module_mutex); + #ifdef CONFIG_MODULE_SIG mod->sig_ok = info->sig_ok; if (!mod->sig_ok) @@ -3122,7 +3199,7 @@ static int load_module(struct load_info *info, const char __user *uargs, /* Now module is in final location, initialize linked lists, etc. */ err = module_unload_init(mod); if (err) - goto free_module; + goto unlink_mod; /* Now we've got everything in the final locations, we can * find optional sections. */ @@ -3157,54 +3234,33 @@ static int load_module(struct load_info *info, const char __user *uargs, goto free_arch_cleanup; } - /* Mark state as coming so strong_try_module_get() ignores us. */ - mod->state = MODULE_STATE_COMING; - - /* Now sew it into the lists so we can get lockdep and oops - * info during argument parsing. No one should access us, since - * strong_try_module_get() will fail. - * lockdep/oops can run asynchronous, so use the RCU list insertion - * function to insert in a way safe to concurrent readers. - * The mutex protects against concurrent writers. - */ -again: - mutex_lock(&module_mutex); - if ((old = find_module(mod->name)) != NULL) { - if (old->state == MODULE_STATE_COMING) { - /* Wait in case it fails to load. */ - mutex_unlock(&module_mutex); - err = wait_event_interruptible(module_wq, - finished_loading(mod->name)); - if (err) - goto free_arch_cleanup; - goto again; - } - err = -EEXIST; - goto unlock; - } - - /* This has to be done once we're sure module name is unique. */ dynamic_debug_setup(info->debug, info->num_debug); - /* Find duplicate symbols */ + mutex_lock(&module_mutex); + /* Find duplicate symbols (must be called under lock). */ err = verify_export_symbols(mod); if (err < 0) - goto ddebug; + goto ddebug_cleanup; + /* This relies on module_mutex for list integrity. */ module_bug_finalize(info->hdr, info->sechdrs, mod); - list_add_rcu(&mod->list, &modules); + + /* Mark state as coming so strong_try_module_get() ignores us, + * but kallsyms etc. can see us. */ + mod->state = MODULE_STATE_COMING; + mutex_unlock(&module_mutex); /* Module is ready to execute: parsing args may do that. */ err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, -32768, 32767, &ddebug_dyndbg_module_param_cb); if (err < 0) - goto unlink; + goto bug_cleanup; /* Link in to syfs. */ err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp); if (err < 0) - goto unlink; + goto bug_cleanup; /* Get rid of temporary copy. */ free_copy(info); @@ -3214,16 +3270,13 @@ again: return do_init_module(mod); - unlink: + bug_cleanup: + /* module_bug_cleanup needs module_mutex protection */ mutex_lock(&module_mutex); - /* Unlink carefully: kallsyms could be walking list. */ - list_del_rcu(&mod->list); module_bug_cleanup(mod); - wake_up_all(&module_wq); - ddebug: - dynamic_debug_remove(info->debug); - unlock: + ddebug_cleanup: mutex_unlock(&module_mutex); + dynamic_debug_remove(info->debug); synchronize_sched(); kfree(mod->args); free_arch_cleanup: @@ -3232,6 +3285,12 @@ again: free_modinfo(mod); free_unload: module_unload_free(mod); + unlink_mod: + mutex_lock(&module_mutex); + /* Unlink carefully: kallsyms could be walking list. */ + list_del_rcu(&mod->list); + wake_up_all(&module_wq); + mutex_unlock(&module_mutex); free_module: module_deallocate(mod, info); free_copy: @@ -3354,6 +3413,8 @@ const char *module_address_lookup(unsigned long addr, preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (within_module_init(addr, mod) || within_module_core(addr, mod)) { if (modname) @@ -3377,6 +3438,8 @@ int lookup_module_symbol_name(unsigned long addr, char *symname) preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (within_module_init(addr, mod) || within_module_core(addr, mod)) { const char *sym; @@ -3401,6 +3464,8 @@ int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (within_module_init(addr, mod) || within_module_core(addr, mod)) { const char *sym; @@ -3428,6 +3493,8 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (symnum < mod->num_symtab) { *value = mod->symtab[symnum].st_value; *type = mod->symtab[symnum].st_info; @@ -3470,9 +3537,12 @@ unsigned long module_kallsyms_lookup_name(const char *name) ret = mod_find_symname(mod, colon+1); *colon = ':'; } else { - list_for_each_entry_rcu(mod, &modules, list) + list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if ((ret = mod_find_symname(mod, name)) != 0) break; + } } preempt_enable(); return ret; @@ -3487,6 +3557,8 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, int ret; list_for_each_entry(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; for (i = 0; i < mod->num_symtab; i++) { ret = fn(data, mod->strtab + mod->symtab[i].st_name, mod, mod->symtab[i].st_value); @@ -3502,6 +3574,7 @@ static char *module_flags(struct module *mod, char *buf) { int bx = 0; + BUG_ON(mod->state == MODULE_STATE_UNFORMED); if (mod->taints || mod->state == MODULE_STATE_GOING || mod->state == MODULE_STATE_COMING) { @@ -3543,6 +3616,10 @@ static int m_show(struct seq_file *m, void *p) struct module *mod = list_entry(p, struct module, list); char buf[8]; + /* We always ignore unformed modules. */ + if (mod->state == MODULE_STATE_UNFORMED) + return 0; + seq_printf(m, "%s %u", mod->name, mod->init_size + mod->core_size); print_unload_info(m, mod); @@ -3603,6 +3680,8 @@ const struct exception_table_entry *search_module_extables(unsigned long addr) preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (mod->num_exentries == 0) continue; @@ -3651,10 +3730,13 @@ struct module *__module_address(unsigned long addr) if (addr < module_addr_min || addr > module_addr_max) return NULL; - list_for_each_entry_rcu(mod, &modules, list) + list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; if (within_module_core(addr, mod) || within_module_init(addr, mod)) return mod; + } return NULL; } EXPORT_SYMBOL_GPL(__module_address); @@ -3707,8 +3789,11 @@ void print_modules(void) printk(KERN_DEFAULT "Modules linked in:"); /* Most callers should already have preempt disabled, but make sure */ preempt_disable(); - list_for_each_entry_rcu(mod, &modules, list) + list_for_each_entry_rcu(mod, &modules, list) { + if (mod->state == MODULE_STATE_UNFORMED) + continue; printk(" %s%s", mod->name, module_flags(mod, buf)); + } preempt_enable(); if (last_unloaded_module[0]) printk(" [last unloaded: %s]", last_unloaded_module); |
