netdev - [PATCH net-next v2 03/18] net: dsa: sja1105: reorder sja1105_first_entry_longer

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Date:   Tue, 12 Apr 2022 12:58:15 +0200
From:   Jakob Koschel <jakobkoschel@...il.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     Jakub Kicinski <kuba@...nel.org>, 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>,
        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>,
        Jakob Koschel <jakobkoschel@...il.com>,
        Colin Ian King <colin.king@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Michael Walle <michael@...le.cc>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        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>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: [PATCH net-next v2 03/18] net: dsa: sja1105: reorder sja1105_first_entry_longer_than with memory allocation

sja1105_first_entry_longer_than() does not make use of the full struct
sja1105_gate_entry *e, just of e->interval which is set from the passed
entry_time.

This means that if there is a gate conflict, we have allocated e for
nothing, just to free it later. Reorder the memory allocation and the
function call, to avoid that and simplify the error unwind path.

Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 drivers/net/dsa/sja1105/sja1105_vl.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_vl.c b/drivers/net/dsa/sja1105/sja1105_vl.c
index 369be2ac3587..e5ea8eb9ec4e 100644
--- a/drivers/net/dsa/sja1105/sja1105_vl.c
+++ b/drivers/net/dsa/sja1105/sja1105_vl.c
@@ -36,7 +36,11 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
 {
 	struct sja1105_gate_entry *e;
 	struct list_head *pos;
-	int rc;
+
+	pos = sja1105_first_entry_longer_than(&gating_cfg->entries,
+					      entry_time, extack);
+	if (IS_ERR(pos))
+		return PTR_ERR(pos);
 
 	e = kzalloc(sizeof(*e), GFP_KERNEL);
 	if (!e)
@@ -45,22 +49,11 @@ static int sja1105_insert_gate_entry(struct sja1105_gating_config *gating_cfg,
 	e->rule = rule;
 	e->gate_state = gate_state;
 	e->interval = entry_time;
-
-	pos = sja1105_first_entry_longer_than(&gating_cfg->entries,
-					      e->interval, extack);
-	if (IS_ERR(pos)) {
-		rc = PTR_ERR(pos);
-		goto err;
-	}
-
 	list_add(&e->list, pos->prev);
 
 	gating_cfg->num_entries++;
 
 	return 0;
-err:
-	kfree(e);
-	return rc;
 }
 
 /* The gate entries contain absolute times in their e->interval field. Convert
-- 
2.25.1