linux-kernel - Re: [PATCH 1/2] staging: r8188eu: call _cancel_timer_ex from _rtw_free_recv

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Date:   Wed, 9 Mar 2022 10:59:51 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Vihas Makwana <makvihas@...il.com>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michael Straube <straube.linux@...il.com>,
        Martin Kaiser <martin@...ser.cx>,
        Pavel Skripkin <paskripkin@...il.com>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] staging: r8188eu: call _cancel_timer_ex from
 _rtw_free_recv_priv

On Wed, Mar 09, 2022 at 02:25:09AM +0530, Vihas Makwana wrote:
> The _rtw_init_recv_priv() initializes precvpriv->signal_stat_timer and
> sets it's timeout interval to 1000 ms. But _rtw_free_recv_priv()
> doesn't cancel the timer and we need to explicitly call
> _cancel_timer_ex() after we call _rtw_free_recv_priv() to cancel the
> timer.
> Call _cancel_timer_ex() from inside _rtw_free_recv_priv() as every init
> function needs a matching free function.
> 
> 
> Signed-off-by: Vihas Makwana <makvihas@...il.com>
> ---
>  drivers/staging/r8188eu/core/rtw_recv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/staging/r8188eu/core/rtw_recv.c b/drivers/staging/r8188eu/core/rtw_recv.c
> index d77d98351..61308eb39 100644
> --- a/drivers/staging/r8188eu/core/rtw_recv.c
> +++ b/drivers/staging/r8188eu/core/rtw_recv.c
> @@ -103,6 +103,7 @@ void _rtw_free_recv_priv(struct recv_priv *precvpriv)
>  	vfree(precvpriv->pallocated_frame_buf);
>  
>  	rtl8188eu_free_recv_priv(padapter);
> +	_cancel_timer_ex(&precvpriv->signal_stat_timer);
>  }

*If* then timer_setup() belongs in _rtw_init_recv_priv() then this is
where the _cancel_timer_ex() belongs, yes.  But what about if the devs
hid it in a different wrong place?

Right the del_timer is in rtw_cancel_all_timer(), which is called
from rtw_usb_if1_deinit() when we remove the USB device.  So something
more complicated is wrong.  I would prefer to just note this as a bug
until we can investigate more completely.

I believe we can del_timer() twice without creating a bug, but I'm not
positive.

regards,
dan carpenter