linux-kernel - hidraw_exit in discarded section (was: Re: [PATCH 1/1] HID: fix tty<->hid deadlock)

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Date:	Thu, 16 Oct 2008 12:32:11 +0200 (CEST)
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Jiri Slaby <jirislaby@...il.com>
cc:	Valdis.Kletnieks@...edu, Alan Cox <alan@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: hidraw_exit in discarded section (was: Re: [PATCH 1/1] HID: fix
 tty<->hid deadlock)

On Thu, 4 Sep 2008, Jiri Slaby wrote:
> hid_compat_load() runs on the default workqueue, it request_module(), it
> execs modprobe, it exits, tty flushes default workqueue, it hangs, because
> we are still in it.
> 
> I haven't run into it since there always was at least one opener of the tty,
> I guess. Could you try the patch below?
> 
> --
> 
> Signed-off-by: Jiri Slaby <jirislaby@...il.com>
> ---
>  drivers/hid/hid-core.c |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 92c16e1..18d952a 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1663,6 +1663,7 @@ static void hid_compat_load(struct work_struct *ws)
>  	request_module("hid-dummy");
>  }
>  static DECLARE_WORK(hid_compat_work, hid_compat_load);
> +static struct workqueue_struct *hid_compat_wq;
>  #endif
>  
>  static int __init hid_init(void)
> @@ -1680,7 +1681,12 @@ static int __init hid_init(void)
>  		goto err_bus;
>  
>  #ifdef CONFIG_HID_COMPAT
> -	schedule_work(&hid_compat_work);
> +	hid_compat_wq = create_workqueue("hid_compat");
> +	if (!hid_compat_wq) {
> +		hidraw_exit();
> +		goto err;
> +	}
> +	queue_work(hid_compat_wq, &hid_compat_work);
>  #endif
>  
>  	return 0;
> @@ -1692,6 +1698,9 @@ err:
>  
>  static void __exit hid_exit(void)
>  {
> +#ifdef CONFIG_HID_COMPAT
> +	destroy_workqueue(hid_compat_wq);
> +#endif
>  	hidraw_exit();
>  	bus_unregister(&hid_bus_type);
>  }

hid_init() is marked __init.
hidraw_exit() is marked __exit.

Hence I get:

    `hidraw_exit' referenced in section `.init.text' of drivers/built-in.o: defined in discarded section `.exit.text' of drivers/built-in.o

and my `enable everything' m68k kernel fails to link.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
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