From: Freddy Xin <freddy@asix•com.tw>
To: David Laight <David.Laight@ACULAB•COM>,
netdev@vger•kernel.org, davem@davemloft•net,
linux-usb@vger•kernel.org, linux-kernel@vger•kernel.org,
louis@asix•com.tw, allan@asix•com.tw
Subject: Re: [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB.
Date: Mon, 16 Dec 2013 14:54:32 +0800 [thread overview]
Message-ID: <52AEA3A8.2020906@asix.com.tw> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B748A@saturn3.aculab.com>
On 2013年12月13日 18:36, David Laight wrote:
>> From: freddy@asix•com.tw
> ...
>> - skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
>> + if (dev->driver_info->flags & FLAG_HW_IPALIGN)
>> + skb = __netdev_alloc_skb(dev->net, size, flags);
>> + else
>> + skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
> Given the definition:
> static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
> unsigned int length, gfp_t gfp)
> {
> struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
>
> if (NET_IP_ALIGN && skb)
> skb_reserve(skb, NET_IP_ALIGN);
> return skb;
> }
>
> It really ought to be possible to code that without an extra conditional.
>
> David
>
>
>
>
The AX88179_178A driver do need to know the value of NET_IP_ALIGN
to determine whether enabling the feature that makes IP header align
on a dword-aligned address, but according to the comments from David
Miller, I need to consider all situations, not just for the case that
NET_IP_ALIGN is zero, so the condition added in rx_submit is just used to
determine whether reserving NET_IP_ALIGN bytes for each SKB.
Freddy
next prev parent reply other threads:[~2013-12-16 7:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-13 9:25 [PATCH 1/1] AX88179_178A: Add FLAG_HW_IPALIGN to determine whether reserving NET_IP_ALIGN bytes for an SKB freddy
[not found] ` <1386926708-2343-1-git-send-email-freddy-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
2013-12-13 10:36 ` David Laight
2013-12-16 6:54 ` Freddy Xin [this message]
[not found] ` <52AEA3A8.2020906-knRN6Y/kmf1NUHwG+Fw1Kw@public.gmane.org>
2013-12-16 10:09 ` David Laight
2013-12-19 3:14 ` Freddy Xin
2013-12-19 10:01 ` David Laight
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=52AEA3A8.2020906@asix.com.tw \
--to=freddy@asix$(echo .)com.tw \
--cc=David.Laight@ACULAB$(echo .)COM \
--cc=allan@asix$(echo .)com.tw \
--cc=davem@davemloft$(echo .)net \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linux-usb@vger$(echo .)kernel.org \
--cc=louis@asix$(echo .)com.tw \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox