linux-kernel - Re: [PATCH net-next v5 08/18] net: sparx5: Replace usage of found with dedicated list iterator variable

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Message-ID: <c499d01d51095ae338cbc63179bdc0e1606cbfef.camel@redhat.com>
Date:   Thu, 28 Apr 2022 11:32:28 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Jakob Koschel <jakobkoschel@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Jakub Kicinski <kuba@...nel.org>, 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>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Casper Andersson <casper.casan@...il.com>,
        Arnd Bergmann <arnd@...db.de>, Jason Gunthorpe <jgg@...pe.ca>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Colin Ian King <colin.king@...el.com>,
        Eric Dumazet <edumazet@...gle.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, bpf@...r.kernel.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 v5 08/18] net: sparx5: Replace usage of found
 with dedicated list iterator variable

Hello,

On Wed, 2022-04-27 at 18:06 +0200, Jakob Koschel wrote:
> To move the list iterator variable into the list_for_each_entry_*()
> macro in the future it should be avoided to use the list iterator
> variable after the loop body.
> 
> To *never* use the list iterator variable after the loop it was
> concluded to use a separate iterator variable instead of a
> found boolean [1].
> 
> This removes the need to use a found variable and simply checking if
> the variable was set, can determine if the break/goto was hit.
> 
> Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
> Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>
> ---
>  .../microchip/sparx5/sparx5_mactable.c        | 25 +++++++++----------
>  1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c b/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
> index a5837dbe0c7e..bb8d9ce79ac2 100644
> --- a/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
> +++ b/drivers/net/ethernet/microchip/sparx5/sparx5_mactable.c
> @@ -362,8 +362,7 @@ static void sparx5_mact_handle_entry(struct sparx5 *sparx5,
>  				     unsigned char mac[ETH_ALEN],
>  				     u16 vid, u32 cfg2)
>  {
> -	struct sparx5_mact_entry *mact_entry;
> -	bool found = false;
> +	struct sparx5_mact_entry *mact_entry = NULL, *iter;
>  	u16 port;
>  
>  	if (LRN_MAC_ACCESS_CFG_2_MAC_ENTRY_ADDR_TYPE_GET(cfg2) !=
> @@ -378,28 +377,28 @@ static void sparx5_mact_handle_entry(struct sparx5 *sparx5,
>  		return;
>  
>  	mutex_lock(&sparx5->mact_lock);
> -	list_for_each_entry(mact_entry, &sparx5->mact_entries, list) {
> -		if (mact_entry->vid == vid &&
> -		    ether_addr_equal(mac, mact_entry->mac)) {
> -			found = true;
> -			mact_entry->flags |= MAC_ENT_ALIVE;
> -			if (mact_entry->port != port) {
> +	list_for_each_entry(iter, &sparx5->mact_entries, list) {
> +		if (iter->vid == vid &&
> +		    ether_addr_equal(mac, iter->mac)) {

I'm sorry for the late feedback.

If you move the 'mact_entry = iter;' statement here, the diffstat will
be slightly smaller and the patch more readable, IMHO.

There is similar situation in the next patch.

Cheers,

Paolo