Re: [PATCH net-next v4 02/18] net: dsa: sja1105: remove use of iterator after list_for_each_entry() loop

From: Florian Fainelli <f.fainelli@gmail.com>
To: Jakob Koschel <jakobkoschel@gmail.com>,
	"David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Vladimir Oltean <olteanv@gmail.com>,
	Lars Povlsen <lars.povlsen@microchip.com>,
	Steen Hegelund <Steen.Hegelund@microchip.com>,
	UNGLinuxDriver@microchip.com, Ariel Elior <aelior@marvell.com>,
	Manish Chopra <manishc@marvell.com>,
	Edward Cree <ecree.xilinx@gmail.com>,
	Martin Habets <habetsm.xilinx@gmail.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>, Jiri Pirko <jiri@resnulli.us>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Casper Andersson <casper.casan@gmail.com>,
	Bjarni Jonasson <bjarni.jonasson@microchip.com>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	Arnd Bergmann <arnd@arndb.de>,
	Colin Ian King <colin.king@intel.com>,
	Eric Dumazet <edumazet@google.com>, Xu Wang <vulab@iscas.ac.cn>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linuxppc-dev@lists.ozlabs.org, bpf@vger.kernel.org,
	Mike Rapoport <rppt@kernel.org>,
	Brian Johannesmeyer <bjohannesmeyer@gmail.com>,
	Cristiano Giuffrida <c.giuffrida@vu.nl>,
	"Bos, H.J." <h.j.bos@vu.nl>,
	Vladimir Oltean <vladimir.oltean@nxp.com>
Subject: Re: [PATCH net-next v4 02/18] net: dsa: sja1105: remove use of iterator after list_for_each_entry() loop
Date: Sat, 16 Apr 2022 12:40:00 -0700	[thread overview]
Message-ID: <725e814d-da65-b77d-1a6e-a029d594944f@gmail.com> (raw)
In-Reply-To: <20220415122947.2754662-3-jakobkoschel@gmail.com>


On 4/15/2022 5:29 AM, Jakob Koschel wrote:
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
> 
> The link below explains that there is a desire to syntactically change
> list_for_each_entry() and list_for_each() such that it becomes
> impossible to use the iterator variable outside the scope of the loop.
> 
> Although sja1105_insert_gate_entry() makes legitimate use of the
> iterator pointer when it breaks out, the pattern it uses may become
> illegal, so it needs to change.
> 
> It is deemed acceptable to use a copy of the loop iterator, and
> sja1105_insert_gate_entry() only needs to know the list_head element
> before which the list insertion should be made. So let's profit from the
> occasion and refactor the list iteration to a dedicated function.
> 
> An additional benefit is given by the fact that with the helper function
> in place, we no longer need to special-case the empty list, since it is
> equivalent to not having found any gating entry larger than the
> specified interval in the list. We just need to insert at the tail of
> that list (list_add vs list_add_tail on an empty list does the same
> thing).
> 
> Link: https://patchwork.kernel.org/project/netdevbpf/patch/20220407102900.3086255-3-jakobkoschel@gmail.com/#24810127
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian

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