From: Jessica Yu <jeyu@redhat.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>,
Seth Jennings <sjenning@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Vojtech Pavlik <vojtech@suse.com>,
Miroslav Benes <mbenes@suse.cz>,
Rusty Russell <rusty@rustcorp.com.au>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>
Cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
Jessica Yu <jeyu@redhat.com>
Subject: [PATCH v2 1/2] ftrace/module: remove ftrace module notifier
Date: Mon, 1 Feb 2016 20:17:35 -0500 [thread overview]
Message-ID: <1454375856-27757-2-git-send-email-jeyu@redhat.com> (raw)
In-Reply-To: <1454375856-27757-1-git-send-email-jeyu@redhat.com>
Remove the ftrace module notifier in favor of directly calling
ftrace_module_enable() and ftrace_release_mod() in the module loader.
Hard-coding the function calls directly in the module loader removes
dependence on the module notifier call chain and provides better
visibility and control over what gets called when, which is important
to kernel utilities such as livepatch.
Signed-off-by: Jessica Yu <jeyu@redhat.com>
---
include/linux/ftrace.h | 6 ++++--
kernel/module.c | 4 ++++
kernel/trace/ftrace.c | 36 +-----------------------------------
3 files changed, 9 insertions(+), 37 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 81de712..c2b340e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -603,6 +603,7 @@ 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_module_enable(struct module *mod);
extern void ftrace_release_mod(struct module *mod);
extern void ftrace_disable_daemon(void);
@@ -612,8 +613,9 @@ static inline int skip_trace(unsigned long ip) { return 0; }
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 void ftrace_module_init(struct module *mod) { }
+static inline void ftrace_module_enable(struct module *mod) { }
+static inline void ftrace_release_mod(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 8358f46..b05d466 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -981,6 +981,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
mod->exit();
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
+ ftrace_release_mod(mod);
+
async_synchronize_full();
/* Store the name of the last unloaded module for diagnostic purposes */
@@ -3295,6 +3297,7 @@ fail:
module_put(mod);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
+ ftrace_release_mod(mod);
free_module(mod);
wake_up_all(&module_wq);
return ret;
@@ -3371,6 +3374,7 @@ static int complete_formation(struct module *mod, struct load_info *info)
mod->state = MODULE_STATE_COMING;
mutex_unlock(&module_mutex);
+ ftrace_module_enable(mod);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_COMING, mod);
return 0;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index eca592f..57a6eea 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4961,7 +4961,7 @@ void ftrace_release_mod(struct module *mod)
mutex_unlock(&ftrace_lock);
}
-static void ftrace_module_enable(struct module *mod)
+void ftrace_module_enable(struct module *mod)
{
struct dyn_ftrace *rec;
struct ftrace_page *pg;
@@ -5038,38 +5038,8 @@ void ftrace_module_init(struct module *mod)
ftrace_process_locs(mod, mod->ftrace_callsites,
mod->ftrace_callsites + mod->num_ftrace_callsites);
}
-
-static int ftrace_module_notify(struct notifier_block *self,
- unsigned long val, void *data)
-{
- struct module *mod = data;
-
- switch (val) {
- case MODULE_STATE_COMING:
- ftrace_module_enable(mod);
- break;
- case MODULE_STATE_GOING:
- ftrace_release_mod(mod);
- break;
- default:
- break;
- }
-
- return 0;
-}
-#else
-static int ftrace_module_notify(struct notifier_block *self,
- unsigned long val, void *data)
-{
- return 0;
-}
#endif /* CONFIG_MODULES */
-struct notifier_block ftrace_module_nb = {
- .notifier_call = ftrace_module_notify,
- .priority = INT_MIN, /* Run after anything that can remove kprobes */
-};
-
void __init ftrace_init(void)
{
extern unsigned long __start_mcount_loc[];
@@ -5098,10 +5068,6 @@ void __init ftrace_init(void)
__start_mcount_loc,
__stop_mcount_loc);
- ret = register_module_notifier(&ftrace_module_nb);
- if (ret)
- pr_warning("Failed to register trace ftrace module exit notifier\n");
-
set_ftrace_early_filters();
return;
--
2.4.3
next prev parent reply other threads:[~2016-02-02 1:18 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 1:17 [PATCH v2 0/2] Fix ordering of ftrace/livepatch calls on module load and unload Jessica Yu
2016-02-02 1:17 ` Jessica Yu [this message]
2016-02-04 13:27 ` [PATCH v2 1/2] ftrace/module: remove ftrace module notifier Petr Mladek
2016-02-04 14:18 ` Steven Rostedt
2016-02-04 15:21 ` Petr Mladek
2016-02-04 15:33 ` Steven Rostedt
2016-02-02 1:17 ` [PATCH v2 2/2] livepatch/module: remove livepatch " Jessica Yu
2016-02-04 14:39 ` Petr Mladek
2016-02-04 14:56 ` Steven Rostedt
2016-02-04 16:47 ` Miroslav Benes
2016-02-05 4:11 ` Jessica Yu
2016-02-05 9:15 ` Miroslav Benes
2016-02-05 10:06 ` Petr Mladek
2016-02-08 0:34 ` Rusty Russell
2016-02-04 17:29 ` [PATCH v2 2/2] " Miroslav Benes
2016-02-04 20:55 ` Josh Poimboeuf
2016-02-05 8:59 ` Miroslav Benes
2016-02-04 10:43 ` [PATCH v2 0/2] Fix ordering of ftrace/livepatch calls on module load and unload Jiri Kosina
2016-02-04 13:29 ` Steven Rostedt
2016-02-05 1:17 ` Rusty Russell
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