netdev - [PATCH wpan-next v2 1/3] mac802154: Move an skb free within the rx path

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Date:   Wed, 26 Oct 2022 11:35:00 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@...enfreihafen.org>,
        linux-wpan@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
        David Girault <david.girault@...vo.com>,
        Romuald Despres <romuald.despres@...vo.com>,
        Frederic Blain <frederic.blain@...vo.com>,
        Nicolas Schodet <nico@...fr.eu.org>,
        Guilhem Imberton <guilhem.imberton@...vo.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: [PATCH wpan-next v2 1/3] mac802154: Move an skb free within the rx path

It may appear clearer to free the skb at the end of the path rather than
in the middle, within a helper.

Move kfree_skb() from the end of __ieee802154_rx_handle_packet() to
right after it in the calling function ieee802154_rx(). Doing so implies
reworking a little bit the exit path.

Suggested-by: Alexander Aring <alex.aring@...il.com>
Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
---
 net/mac802154/rx.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/net/mac802154/rx.c b/net/mac802154/rx.c
index 334aa4e415cc..9f3e72a278cb 100644
--- a/net/mac802154/rx.c
+++ b/net/mac802154/rx.c
@@ -234,8 +234,6 @@ __ieee802154_rx_handle_packet(struct ieee802154_local *local,
 		skb = NULL;
 		break;
 	}
-
-	kfree_skb(skb);
 }
 
 static void
@@ -274,7 +272,7 @@ void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb)
 	WARN_ON_ONCE(softirq_count() == 0);
 
 	if (local->suspended)
-		goto drop;
+		goto free_skb;
 
 	/* TODO: When a transceiver omits the checksum here, we
 	 * add an own calculated one. This is currently an ugly
@@ -292,20 +290,17 @@ void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb)
 	/* Level 1 filtering: Check the FCS by software when relevant */
 	if (local->hw.phy->filtering == IEEE802154_FILTERING_NONE) {
 		crc = crc_ccitt(0, skb->data, skb->len);
-		if (crc) {
-			rcu_read_unlock();
+		if (crc)
 			goto drop;
-		}
 	}
 	/* remove crc */
 	skb_trim(skb, skb->len - 2);
 
 	__ieee802154_rx_handle_packet(local, skb);
 
-	rcu_read_unlock();
-
-	return;
 drop:
+	rcu_read_unlock();
+free_skb:
 	kfree_skb(skb);
 }
 
-- 
2.34.1