From: Ivo van Doorn <ivdoorn@gmail.com>
To: Gertjan van Wingerde <gwingerde@gmail.com>
Subject: Re: [PATCH v3 1/4] rt2x00: Further L2 padding fixes.
Date: Tue, 1 Dec 2009 20:07:00 +0100
Cc: users@rt2x00.serialmonkey.com, linux-wireless@vger.kernel.org,
	Benoit Papillault <benoit.papillault@free.fr>,
	John Linville <linville@tuxdriver.com>
References: <1259615298-2305-1-git-send-email-gwingerde@gmail.com> <1259615298-2305-2-git-send-email-gwingerde@gmail.com>
In-Reply-To: <1259615298-2305-2-git-send-email-gwingerde@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-15"
Message-Id: <200912012007.01188.IvDoorn@gmail.com>
Sender: linux-wireless-owner@vger.kernel.org

On Monday 30 November 2009, Gertjan van Wingerde wrote:
> Fix a couple of more bugs in the L2 padding code:
> 1. Compute the amount of L2 padding correctly (in 3 places).
> 2. Trim the skb correctly when the L2 padding has been applied.
> 
> Also introduce a central macro the compute the L2 padding size.
> 
> Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>

Acked-by: Ivo van Doorn <IvDoorn@gmail.com>

> ---
>  drivers/net/wireless/rt2x00/rt2x00.h      |    6 ++++++
>  drivers/net/wireless/rt2x00/rt2x00queue.c |    8 +++++---
>  2 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
> index dcfc8c2..6594d2f 100644
> --- a/drivers/net/wireless/rt2x00/rt2x00.h
> +++ b/drivers/net/wireless/rt2x00/rt2x00.h
> @@ -113,6 +113,12 @@
>  	(  ((unsigned long)((__skb)->data + (__header))) & 3 )
>  
>  /*
> + * Determine the number of L2 padding bytes required between the header and
> + * the payload.
> + */
> +#define L2PAD_SIZE(__hdrlen)	(-(__hdrlen) & 3)
> +
> +/*
>   * Constants for extra TX headroom for alignment purposes.
>   */
>  #define RT2X00_ALIGN_SIZE	4 /* Only whole frame needs alignment */
> diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c
> index b8f0954..21d5876 100644
> --- a/drivers/net/wireless/rt2x00/rt2x00queue.c
> +++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
> @@ -181,7 +181,7 @@ void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
>  	unsigned int frame_length = skb->len;
>  	unsigned int header_align = ALIGN_SIZE(skb, 0);
>  	unsigned int payload_align = ALIGN_SIZE(skb, header_length);
> -	unsigned int l2pad = 4 - (payload_align - header_align);
> +	unsigned int l2pad = L2PAD_SIZE(header_length);
>  
>  	if (header_align == payload_align) {
>  		/*
> @@ -216,6 +216,7 @@ void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
>  		memmove(skb->data + header_length + l2pad,
>  			skb->data + header_length + l2pad + payload_align,
>  			frame_length - header_length);
> +		skb_trim(skb, frame_length + l2pad);
>  		skbdesc->flags |= SKBDESC_L2_PADDED;
>  	}
>  }
> @@ -223,7 +224,7 @@ void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
>  void rt2x00queue_remove_l2pad(struct sk_buff *skb, unsigned int header_length)
>  {
>  	struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
> -	unsigned int l2pad = 4 - (header_length & 3);
> +	unsigned int l2pad = L2PAD_SIZE(header_length);
>  
>  	if (!l2pad || (skbdesc->flags & SKBDESC_L2_PADDED))
>  		return;
> @@ -346,7 +347,8 @@ static void rt2x00queue_create_tx_descriptor(struct queue_entry *entry,
>  	 * Header and alignment information.
>  	 */
>  	txdesc->header_length = ieee80211_get_hdrlen_from_skb(entry->skb);
> -	txdesc->l2pad = ALIGN_SIZE(entry->skb, txdesc->header_length);
> +	if (test_bit(DRIVER_REQUIRE_L2PAD, &rt2x00dev->flags))
> +		txdesc->l2pad = L2PAD_SIZE(txdesc->header_length);
>  
>  	/*
>  	 * Check whether this frame is to be acked.