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Message-Id: <AAB64C72-5B45-4BA1-BB48-106F08BDFF1B@gmail.com>
Date: Sat, 9 Apr 2022 01:58:29 +0200
From: Jakob Koschel <jakobkoschel@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>,
Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...il.com>,
Florian Fainelli <f.fainelli@...il.com>,
Vladimir Oltean <olteanv@...il.com>,
Lars Povlsen <lars.povlsen@...rochip.com>,
Steen Hegelund <Steen.Hegelund@...rochip.com>,
UNGLinuxDriver@...rochip.com, Ariel Elior <aelior@...vell.com>,
Manish Chopra <manishc@...vell.com>,
Edward Cree <ecree.xilinx@...il.com>,
Martin Habets <habetsm.xilinx@...il.com>,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Jiri Pirko <jiri@...nulli.us>,
Casper Andersson <casper.casan@...il.com>,
Bjarni Jonasson <bjarni.jonasson@...rochip.com>,
Colin Ian King <colin.king@...el.com>,
Michael Walle <michael@...le.cc>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Arnd Bergmann <arnd@...db.de>,
Eric Dumazet <edumazet@...gle.com>,
Di Zhu <zhudi21@...wei.com>, Xu Wang <vulab@...as.ac.cn>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org, Mike Rapoport <rppt@...nel.org>,
Brian Johannesmeyer <bjohannesmeyer@...il.com>,
Cristiano Giuffrida <c.giuffrida@...nl>,
"Bos, H.J." <h.j.bos@...nl>
Subject: Re: [PATCH net-next 02/15] net: dsa: sja1105: Remove usage of
iterator for list_add() after loop
Hello Jakub,
> On 8. Apr 2022, at 05:54, Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Thu, 7 Apr 2022 12:28:47 +0200 Jakob Koschel wrote:
>> diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
>> index b7e95d60a6e4..cfcae4d19eef 100644
>> --- a/drivers/net/dsa/sja1105/sja1105_vl.c
>> +++ b/drivers/net/dsa/sja1105/sja1105_vl.c
>> @@ -27,20 +27,24 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
>> if (list_empty(&gating_cfg->entries)) {
>> list_add(&e->list, &gating_cfg->entries);
>> } else {
>> - struct sja1105_gate_entry *p;
>> + struct sja1105_gate_entry *p = NULL, *iter;
>>
>> - list_for_each_entry(p, &gating_cfg->entries, list) {
>> - if (p->interval == e->interval) {
>> + list_for_each_entry(iter, &gating_cfg->entries, list) {
>> + if (iter->interval == e->interval) {
>> NL_SET_ERR_MSG_MOD(extack,
>> "Gate conflict");
>> rc = -EBUSY;
>> goto err;
>> }
>>
>> - if (e->interval < p->interval)
>> + if (e->interval < iter->interval) {
>> + p = iter;
>> + list_add(&e->list, iter->list.prev);
>> break;
>> + }
>> }
>> - list_add(&e->list, p->list.prev);
>> + if (!p)
>> + list_add(&e->list, gating_cfg->entries.prev);
>
> This turns a pretty slick piece of code into something ugly :(
> I'd rather you open coded the iteration here than make it more
> complex to satisfy "safe coding guidelines".
I'm not entirely sure I understand what you mean with
"open coded the iteration". But maybe the solution proposed by Vladimir [1]
works for you? I'm planning to rewrite the cases in that way for the relevant
ones.
>
> Also the list_add() could be converted to list_add_tail().
Good point, I wasn't sure if that's considered as something that should be
done as a separate change. I'm happy to include it in v2.
Thanks for the input.
Jakob
[1] https://lore.kernel.org/linux-kernel/20220408114120.tvf2lxvhfqbnrlml@skbuf/
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