linux-kernel - Re: [PATCH] rtl8188eu: rtw_xmit: Replace rcu_dereference() with rcu_access

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Message-ID: <20140908204830.GA19307@kroah.com>
Date:	Mon, 8 Sep 2014 13:48:30 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Andreea-Cristina Bernat <bernat.ada@...il.com>
Cc:	Larry.Finger@...inger.net, navin.patidar@...il.com,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	paulmck@...ux.vnet.ibm.com
Subject: Re: [PATCH] rtl8188eu: rtw_xmit: Replace rcu_dereference() with
 rcu_access_pointer()

On Thu, Sep 04, 2014 at 08:15:48PM +0300, Andreea-Cristina Bernat wrote:
> The "br_port" local variables obtained through the rcu_dereference() calls are
> not dereferenced in the rest of their function.
> Therefore, it is recommended to use rcu_access_pointer() instead of
> rcu_dereference().
> This patch makes the replacements.
> 
> The first step to detect this was made with the following Coccinelle semantic
> patch:
> @@
> identifier p;
> @@
> 
> * p = rcu_dereference(...)
> ... when any
>     when != p
> (
> * if( (<+...p...+>) ) { ... }
> |
> * while( (<+...p...+>) ) { ... }
> )
> ... when != p
> 
> After the analysis of the output, the change was made manually.
> 
> Signed-off-by: Andreea-Cristina Bernat <bernat.ada@...il.com>
> ---
>  drivers/staging/rtl8188eu/core/rtw_xmit.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/rtl8188eu/core/rtw_xmit.c b/drivers/staging/rtl8188eu/core/rtw_xmit.c
> index 1413ec8..93228dc 100644
> --- a/drivers/staging/rtl8188eu/core/rtw_xmit.c
> +++ b/drivers/staging/rtl8188eu/core/rtw_xmit.c
> @@ -1684,7 +1684,7 @@ static int rtw_br_client_tx(struct adapter *padapter, struct sk_buff **pskb)
>  	void *br_port = NULL;
>  
>  	rcu_read_lock();
> -	br_port = rcu_dereference(padapter->pnetdev->rx_handler_data);
> +	br_port = rcu_access_pointer(padapter->pnetdev->rx_handler_data);
>  	rcu_read_unlock();
>  	spin_lock_bh(&padapter->br_ext_lock);
>  	if (!(skb->data[0] & 1) && br_port &&
> @@ -1868,7 +1868,7 @@ s32 rtw_xmit(struct adapter *padapter, struct sk_buff **ppkt)
>  	}
>  
>  	rcu_read_lock();
> -	br_port = rcu_dereference(padapter->pnetdev->rx_handler_data);
> +	br_port = rcu_access_pointer(padapter->pnetdev->rx_handler_data);
>  	rcu_read_unlock();
>  
>  	if (br_port && check_fwstate(pmlmepriv, WIFI_STATION_STATE|WIFI_ADHOC_STATE)) {

This patch doesn't apply at all to my staging-next branch of the
staging.git tree on git.kernel.org :(

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