netdev - Re: [RFC 1/3] networking: make skb_put & friends return void pointers

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Message-ID: <1497612396.10546.7.camel@perches.com>
Date:   Fri, 16 Jun 2017 04:26:36 -0700
From:   Joe Perches <joe@...ches.com>
To:     Johannes Berg <johannes@...solutions.net>,
        Bjørn Mork <bjorn@...k.no>
Cc:     netdev@...r.kernel.org
Subject: Re: [RFC 1/3] networking: make skb_put & friends return void
 pointers

On Fri, 2017-06-16 at 13:03 +0200, Johannes Berg wrote:
> On Fri, 2017-06-16 at 03:39 -0700, Joe Perches wrote:
> > 
> > I would suggest avoiding using skb_put_u8 as it
> > would suggest there should be skb_put_u16 etc
> 
> If there are enough users, I don't know why we wouldn't add it? Though
> it should be _unaligned_le16 and _unaligned_be16, if at all :)

Maybe.

Avoid api explosion can be good.

Maybe using skb_put_data() and optimizing away size
using __builtin_constant_p and a switch statement
could do more or less the same thing.

$ git grep -P "\*\s*\(.*\*\s*\)\s*skb_put" *
drivers/net/wireless/intel/ipw2x00/ipw2200.c:		*(__le16*)skb_put(dst, sizeof(u16)) = cpu_to_le16(
drivers/net/wireless/intel/ipw2x00/ipw2200.c:			*(__le16*)skb_put(dst, sizeof(u16)) =
drivers/net/wireless/intel/ipw2x00/ipw2200.c:			*(__le16*)skb_put(dst, sizeof(u16)) =
drivers/net/wireless/intel/ipw2x00/ipw2200.c:			*(__le16*)skb_put(dst, sizeof(u16)) =
drivers/s390/net/ctcm_fsms.c:		*((__u16 *)skb_put(ch->trans_skb, 2)) = ch->collect_len + 2;
drivers/atm/fore200e.c:	*((u32*)skb_put(skb, 4)) = cell_header;
net/l2tp/l2tp_ip.c:	*((__be32 *) skb_put(skb, 4)) = 0;
net/atm/signaling.c:	*(struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg)) = *msg;