On Sat, Feb 28, 2015 at 9:21 PM, David Miller <davem@xxxxxxxxxxxxx> wrote: > From: Eyal Birger <eyal.birger@xxxxxxxxx> > Date: Thu, 26 Feb 2015 21:07:01 +0200 > >> As part of an effort to move skb->dropcount to skb->cb[], 4 bytes >> of additional room are needed in skb->cb[] in packet sockets. >> >> Store the skb original length in skb->dev instead of skb->cb[] for >> this purpose. >> >> Signed-off-by: Eyal Birger <eyal.birger@xxxxxxxxx> > > I'm a little confused, why is this even needed? > > packet_skb_cb is 24 bytes by my calculations, which is much > smaller than the cb[] size which is 48 bytes. Note the BUILD_BUG_ON in packet_rcv(). packet_skb_cb may contain an address as large as MAX_ADDR_LEN (32) Therefore the required space is sizeof(packet_skb_cb) + MAX_ADDR_LEN - 8 which is 48 bytes before this change. Regards, Eyal. -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
