Re: [PATCH] __libc_exit_fini forgets to do pthread_mutex_unlock

[Markus Wichmann <nullplan@gmx.net>]

Am Wed, Jul 02, 2025 at 10:28:54AM +0800 schrieb rebecca.zhang.cn@windriver.com:
> From: Rebecca Zhang <rebecca.zhang.cn@windriver.com>
> 
> This commit fixes the issue that __libc_exit_fini only do
> pthread_mutex_lock, but forget to do pthread_mutex_unlock.
> ---
>  ldso/dynlink.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/ldso/dynlink.c b/ldso/dynlink.c
> index ceca3c9..7885675 100644
> --- a/ldso/dynlink.c
> +++ b/ldso/dynlink.c
> @@ -1492,6 +1492,7 @@ void __libc_exit_fini()
>  			fpaddr(p, dyn[DT_FINI])();
>  #endif
>  	}
> +	pthread_mutex_unlock(&init_fini_lock);
>  }
>  
>  void __ldso_atfork(int who)
> -- 
> 2.34.1
> 
I think that is a deliberate omision. __libc_exit_fini() is called on
process exit. After it runs, it must not run again, and no new
initializer must run at all. The process will exit very soon anyway. The
only way to deadlock here is if a destructor calls exit(), which they
aren't allowed to do.

Ciao,
Markus