From 79465d2fd48e68940c2bdecddbdecd45bbba06fe Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 28 Apr 2014 11:05:43 +0930 Subject: module: remove warning about waiting module removal. We remove the waiting module removal in commit 3f2b9c9cdf38 (September 2013), but it turns out that modprobe in kmod (< version 16) was asking for waiting module removal. No one noticed since modprobe would check for 0 usage immediately before trying to remove the module, and the race is unlikely. However, it means that anyone running old (but not ancient) kmod versions is hitting the printk designed to see if anyone was running "rmmod -w". All reports so far have been false positives, so remove the warning. Fixes: 3f2b9c9cdf389e303b2273679af08aab5f153517 Reported-by: Valerio Vanni Cc: Elliott, Robert (Server Storage) Cc: stable@kernel.org Acked-by: Lucas De Marchi Signed-off-by: Rusty Russell --- kernel/module.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index 11869408f79..ae7821898bf 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -815,9 +815,6 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, return -EFAULT; name[MODULE_NAME_LEN-1] = '\0'; - if (!(flags & O_NONBLOCK)) - pr_warn("waiting module removal not supported: please upgrade\n"); - if (mutex_lock_interruptible(&module_mutex) != 0) return -EINTR; -- cgit v1.2.3-70-g09d2 From a949ae560a511fe4e3adf48fa44fefded93e5c2b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Thu, 24 Apr 2014 10:40:12 -0400 Subject: ftrace/module: Hardcode ftrace_module_init() call into load_module() A race exists between module loading and enabling of function tracer. CPU 1 CPU 2 ----- ----- load_module() module->state = MODULE_STATE_COMING register_ftrace_function() mutex_lock(&ftrace_lock); ftrace_startup() update_ftrace_function(); ftrace_arch_code_modify_prepare() set_all_module_text_rw(); ftrace_arch_code_modify_post_process() set_all_module_text_ro(); [ here all module text is set to RO, including the module that is loading!! ] blocking_notifier_call_chain(MODULE_STATE_COMING); ftrace_init_module() [ tries to modify code, but it's RO, and fails! ftrace_bug() is called] When this race happens, ftrace_bug() will produces a nasty warning and all of the function tracing features will be disabled until reboot. The simple solution is to treate module load the same way the core kernel is treated at boot. To hardcode the ftrace function modification of converting calls to mcount into nops. This is done in init/main.c there's no reason it could not be done in load_module(). This gives a better control of the changes and doesn't tie the state of the module to its notifiers as much. Ftrace is special, it needs to be treated as such. The reason this would work, is that the ftrace_module_init() would be called while the module is in MODULE_STATE_UNFORMED, which is ignored by the set_all_module_text_ro() call. Link: http://lkml.kernel.org/r/1395637826-3312-1-git-send-email-indou.takao@jp.fujitsu.com Reported-by: Takao Indoh Acked-by: Rusty Russell Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 2 ++ kernel/module.c | 3 +++ kernel/trace/ftrace.c | 27 ++++----------------------- 3 files changed, 9 insertions(+), 23 deletions(-) (limited to 'kernel/module.c') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 9212b017bc7..ae9504b4b67 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -535,6 +535,7 @@ static inline int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_a extern int ftrace_arch_read_dyn_info(char *buf, int size); extern int skip_trace(unsigned long ip); +extern void ftrace_module_init(struct module *mod); extern void ftrace_disable_daemon(void); extern void ftrace_enable_daemon(void); @@ -544,6 +545,7 @@ static inline int ftrace_force_update(void) { return 0; } static inline void ftrace_disable_daemon(void) { } static inline void ftrace_enable_daemon(void) { } static inline void ftrace_release_mod(struct module *mod) {} +static inline void ftrace_module_init(struct module *mod) {} static inline __init int register_ftrace_command(struct ftrace_func_command *cmd) { return -EINVAL; diff --git a/kernel/module.c b/kernel/module.c index 11869408f79..5f14fec9f82 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3271,6 +3271,9 @@ static int load_module(struct load_info *info, const char __user *uargs, dynamic_debug_setup(info->debug, info->num_debug); + /* Ftrace init must be called in the MODULE_STATE_UNFORMED state */ + ftrace_module_init(mod); + /* Finally it's fully formed, ready to start executing. */ err = complete_formation(mod, info); if (err) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 1fd4b947921..4a54a25afa2 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4330,16 +4330,11 @@ static void ftrace_init_module(struct module *mod, ftrace_process_locs(mod, start, end); } -static int ftrace_module_notify_enter(struct notifier_block *self, - unsigned long val, void *data) +void ftrace_module_init(struct module *mod) { - struct module *mod = data; - - if (val == MODULE_STATE_COMING) - ftrace_init_module(mod, mod->ftrace_callsites, - mod->ftrace_callsites + - mod->num_ftrace_callsites); - return 0; + ftrace_init_module(mod, mod->ftrace_callsites, + mod->ftrace_callsites + + mod->num_ftrace_callsites); } static int ftrace_module_notify_exit(struct notifier_block *self, @@ -4353,11 +4348,6 @@ static int ftrace_module_notify_exit(struct notifier_block *self, return 0; } #else -static int ftrace_module_notify_enter(struct notifier_block *self, - unsigned long val, void *data) -{ - return 0; -} static int ftrace_module_notify_exit(struct notifier_block *self, unsigned long val, void *data) { @@ -4365,11 +4355,6 @@ static int ftrace_module_notify_exit(struct notifier_block *self, } #endif /* CONFIG_MODULES */ -struct notifier_block ftrace_module_enter_nb = { - .notifier_call = ftrace_module_notify_enter, - .priority = INT_MAX, /* Run before anything that can use kprobes */ -}; - struct notifier_block ftrace_module_exit_nb = { .notifier_call = ftrace_module_notify_exit, .priority = INT_MIN, /* Run after anything that can remove kprobes */ @@ -4403,10 +4388,6 @@ void __init ftrace_init(void) __start_mcount_loc, __stop_mcount_loc); - ret = register_module_notifier(&ftrace_module_enter_nb); - if (ret) - pr_warning("Failed to register trace ftrace module enter notifier\n"); - ret = register_module_notifier(&ftrace_module_exit_nb); if (ret) pr_warning("Failed to register trace ftrace module exit notifier\n"); -- cgit v1.2.3-70-g09d2