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authorJessica Yu <jeyu@redhat.com>2016-02-16 17:32:33 -0500
committerJiri Kosina <jkosina@suse.cz>2016-02-17 22:14:06 +0100
commit7dcd182bec271ab341b05b66b6006995795fc0e7 (patch)
treeb2850092d0b57e9c33bb8743ca5053ca6404552d /kernel/module.c
parent383bf44d1a8b18de5c26ec2a48c6822681b50984 (diff)
ftrace/module: remove ftrace module notifier
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. This fixes a notifier ordering issue in which the ftrace module notifier (and hence ftrace_module_enable()) for coming modules was being called after klp_module_notify(), which caused livepatch modules to initialize incorrectly. This patch removes dependence on the module notifier call chain in favor of hard coding the corresponding function calls in the module loader. This ensures that ftrace and livepatch code get called in the correct order on patch module load and unload. Fixes: 5156dca34a3e ("ftrace: Fix the race between ftrace and insmod") Signed-off-by: Jessica Yu <jeyu@redhat.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Petr Mladek <pmladek@suse.cz> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'kernel/module.c')
-rw-r--r--kernel/module.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 8358f4697c0c..b05d466cfa02 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;