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From: Rusty Russell <rusty@rustcorp.com.au>
Date: Fri, 28 Sep 2012 05:01:03 +0000 (+0930)
Subject: module: fix symbol waiting when module fails before init
X-Git-Tag: v3.7-rc1~2^2~33
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=6f13909f4fe9652f1
module: fix symbol waiting when module fails before init
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 <rusty@rustcorp.com.au>
---
diff --git a/kernel/module.c b/kernel/module.c
index 7f2ee45f..63cf6e7 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2959,7 +2959,7 @@ static struct module *load_module(void __user *umod,
/* 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 *, umod,
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 *, umod,
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 *, umod,
mod->init_ro_size = 0;
mod->init_text_size = 0;
mutex_unlock(&module_mutex);
+ wake_up_all(&module_wq);
return 0;
}
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