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Message-ID: <0681089db5bdc5acc805ed52130dc9a5.squirrel@webmail.it-technology.at>
Date: Sat, 18 Apr 2009 17:33:15 +0200 (CEST)
From: "Peter Holik" <peter@...ik.at>
To: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
Cc: "LKML" <linux-kernel@...r.kernel.org>,
"Netdev" <netdev@...r.kernel.org>, linux-usb@...r.kernel.org
Subject: Re: [Resend][PATCH] usb driver for intellon int51x1 based PLC like
devolo dlan duo
>> +static struct sk_buff *int51x1_tx_fixup(struct usbnet *dev,
>> + struct sk_buff *skb, gfp_t flags)
>> +{
>> + int pack_len = skb->len;
>> + int headroom = skb_headroom(skb);
>> + int tailroom = skb_tailroom(skb);
>> + int need_tail = 0;
>> + __le16 *len;
>> +
>> + /*
>> + * usbnet would send a ZLP if packetlength mod urbsize == 0 for us,
>> + * but we need to know ourself, because this would add to the length
>> + * we send down to the device...
>> + */
>> + if (!((pack_len + INT51X1_HEADER_SIZE) % dev->maxpacket))
>> + need_tail = 1;
>> +
>> + /* if packet and our header is smaler than 64 pad to 64 (+ ZLP) */
>> + if ((pack_len + INT51X1_HEADER_SIZE + need_tail) < dev->maxpacket + 1)
>> + need_tail = dev->maxpacket + 1 - pack_len - INT51X1_HEADER_SIZE;
>
> This is totally crazy code fragment, first need_tail is used like a
> boolean? But on the same some +1 scalar trick is being done? Is there some
> reason why DIV_ROUND_UP (linux/kernel.h) won't do what you want here and
> then you can trivally find diff = new - old ?
>
maybe this version is not so crazy for you?
/* if packet and our header is smaler than 64 pad to 64 (+ ZLP) */
if ((pack_len + INT51X1_HEADER_SIZE) < dev->maxpacket)
need_tail = dev->maxpacket - pack_len - INT51X1_HEADER_SIZE + 1;
/*
* usbnet would send a ZLP if packetlength mod urbsize == 0 for us,
* but we need to know ourself, because this would add to the length
* we send down to the device...
*/
else if (!((pack_len + INT51X1_HEADER_SIZE) % dev->maxpacket))
need_tail = 1;
cu Peter
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