linux-kernel - Re: [PATCH v2] staging: gdm72xx: fix reference counting in gdm_wimax_event

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Message-ID: <CAHdPZaOTvF=e3j8ypzK8_V5Uh_8Nk1U74uVe4tcXs+cdQvimjg@mail.gmail.com>
Date:	Wed, 25 Jul 2012 10:35:58 +0545
From:	"devendra.aaru" <devendra.aaru@...il.com>
To:	Ben Chan <benchan@...omium.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH v2] staging: gdm72xx: fix reference counting in gdm_wimax_event_init

On Tue, Jul 24, 2012 at 8:34 PM, Ben Chan <benchan@...omium.org> wrote:
> This patch fixes the commit "staging/gdm72xx: cleanup little at
> gdm_wimax_event_rcv" (8df858ea76b76dde9a39d4edd9aaded983582cfe),
> which mishandles the reference counting of wm_event.
>
> Signed-off-by: Ben Chan <benchan@...omium.org>
> ---
> Fixed the commit message as suggested by Dan Carpenter.
>
>  drivers/staging/gdm72xx/gdm_wimax.c |   16 ++++++++++------
>  1 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/gdm72xx/gdm_wimax.c b/drivers/staging/gdm72xx/gdm_wimax.c
> index 0716efc..6cb8107 100644
> --- a/drivers/staging/gdm72xx/gdm_wimax.c
> +++ b/drivers/staging/gdm72xx/gdm_wimax.c
> @@ -258,12 +258,16 @@ static int gdm_wimax_event_init(void)
>         if (!wm_event.ref_cnt) {
>                 wm_event.sock = netlink_init(NETLINK_WIMAX,
>                                                 gdm_wimax_event_rcv);
> -               if (wm_event.sock)
> -                       wm_event.ref_cnt++;
> -               INIT_LIST_HEAD(&wm_event.evtq);
> -               INIT_LIST_HEAD(&wm_event.freeq);
> -               INIT_WORK(&wm_event.ws, __gdm_wimax_event_send);
> -               spin_lock_init(&wm_event.evt_lock);
> +               if (wm_event.sock) {
> +                       INIT_LIST_HEAD(&wm_event.evtq);
> +                       INIT_LIST_HEAD(&wm_event.freeq);
> +                       INIT_WORK(&wm_event.ws, __gdm_wimax_event_send);
> +                       spin_lock_init(&wm_event.evt_lock);
> +               }
> +       }
> +
> +       if (wm_event.sock) {
> +               wm_event.ref_cnt++;
>                 return 0;
>         }
>
> --
> 1.7.7.3
>

Hi Ben,

I have some basic understanding about this flow of the function,

Here is my understanding of the thing i have done when i was doing
some cleanups to this driver.

The ref_cnt will be 0 at first time. if so the sock creation happens
only once, and register_wimax_device only calls this function.
so i think doing the ref_cnt++ inside the if (!wm_event.ref_cnt) is valid.

Please suggest me if i am wrong.

Thanks,
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