+++ Josh Poimboeuf [29/01/16 11:30 -0600]:
On Fri, Jan 29, 2016 at 05:30:46PM +0100, Miroslav Benes wrote:
Otherwise than that it looks good. I agree there are advantages to split
the notifiers. For example we can replace the coming one with the function
call somewhere in load_module() to improve error handling if the patching
fails while loading a module. This would be handy with a consistency model
in the future.
Yeah, we'll need something like that eventually. Though we'll need to
make sure that ftrace_module_enable() is still called beforehand, after
setting MODULE_STATE_COMING state, due to the race described in 5156dca.
Something like:
[note: klp_module_notify_coming() is replaced with klp_module_enable()]
diff --git a/kernel/module.c b/kernel/module.c
index 8358f46..aeabd81 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3371,6 +3371,13 @@ static int complete_formation(struct module *mod, struct load_info *info)
mod->state = MODULE_STATE_COMING;
mutex_unlock(&module_mutex);
+ ftrace_module_enable(mod);
+ err = klp_module_enable(mod);
+ if (err) {
+ ftrace_release_mod(mod);
+ return err;
+ }
If we go this route, should we should print a big warning ("Livepatch
couldn't patch loading module X") instead of aborting the module load
completely?
+
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..c42cf37 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5045,9 +5045,6 @@ static int ftrace_module_notify(struct notifier_block *self,
struct module *mod = data;
switch (val) {
- case MODULE_STATE_COMING:
- ftrace_module_enable(mod);
- break;
case MODULE_STATE_GOING:
ftrace_release_mod(mod);
break;
--
Josh
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