On Fri, Sep 14, 2012 at 4:09 AM, Rusty Russell <ru...@rustcorp.com.au> wrote:
> We use resolve_symbol_wait(), which blocks if the module containing
> the symbol is still loading. However:
>
> 1) The module_wq we use is only woken after calling the modules' init
> function, but there are other failure paths after the module is
> placed in the linked list where we need to do the same thing.
>
> 2) wake_up() only wakes one waiter, and our waitqueue is shared by all
> modules, so we need to wake them all.
>
> 3) wake_up_all() doesn't imply a memory barrier: I feel happier calling
> it after we've grabbed and dropped the module_mutex, not just after
> the state assignment.
>
> Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>
> ---
> kernel/module.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -2959,7 +2959,7 @@ static struct module *load_module(void _
> /* 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:
> @@ -3034,7 +3034,7 @@ SYSCALL_DEFINE3(init_module, void __user
> blocking_notifier_call_chain(&module_notify_list,
> MODULE_STATE_GOING, mod);
> free_module(mod);
> - wake_up(&module_wq);
> + wake_up_all(&module_wq);
> return ret;
> }
> if (ret > 0) {
> @@ -3046,9 +3046,8 @@ SYSCALL_DEFINE3(init_module, void __user
> dump_stack();
> }
>
> - /* Now it's a first class citizen! Wake up anyone waiting for it. */
> + /* Now it's a first class citizen! */
> mod->state = MODULE_STATE_LIVE;
> - wake_up(&module_wq);
> blocking_notifier_call_chain(&module_notify_list,
> MODULE_STATE_LIVE, mod);
>
> @@ -3071,6 +3070,7 @@ SYSCALL_DEFINE3(init_module, void __user
> mod->init_ro_size = 0;
> mod->init_text_size = 0;
> mutex_unlock(&module_mutex);
> + wake_up_all(&module_wq);
>
> return 0;
> }
Ack.
cheers,
Lucas De Marchi
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