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From:   Dario Binacchi <dariobin@libero.it>
To:     linux-kernel@vger.kernel.org
Cc:     Gianluca Falavigna <gianluca.falavigna@inwind.it>,
        Dario Binacchi <dariobin@libero.it>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Tong Zhang <ztong0001@gmail.com>,
        Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
        Wolfgang Grandegger <wg@grandegger.com>,
        YueHaibing <yuehaibing@huawei.com>,
        Zhang Qilong <zhangqilong3@huawei.com>,
        linux-can@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH 1/3] can: c_can: exit c_can_do_tx() early if no frames have been sent
Date:   Sun,  6 Jun 2021 22:17:03 +0200
Message-Id: <20210606201705.31307-2-dariobin@libero.it>
In-Reply-To: <20210606201705.31307-1-dariobin@libero.it>
References: <20210606201705.31307-1-dariobin@libero.it>
Precedence: bulk

The c_can_poll() handles RX/TX events unconditionally. It may therefore
happen that c_can_do_tx() is called unnecessarily because the interrupt
was triggered by the reception of a frame. In these cases, we avoid to
execute unnecessary statements and exit immediately.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
---

 drivers/net/can/c_can/c_can.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 313793f6922d..2b203bf004f9 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -721,17 +721,18 @@ static void c_can_do_tx(struct net_device *dev)
 		pkts++;
 	}
 
+	if (!pkts)
+		return;
+
 	/* Clear the bits in the tx_active mask */
 	atomic_sub(clr, &priv->tx_active);
 
 	if (clr & BIT(priv->msg_obj_tx_num - 1))
 		netif_wake_queue(dev);
 
-	if (pkts) {
-		stats->tx_bytes += bytes;
-		stats->tx_packets += pkts;
-		can_led_event(dev, CAN_LED_EVENT_TX);
-	}
+	stats->tx_bytes += bytes;
+	stats->tx_packets += pkts;
+	can_led_event(dev, CAN_LED_EVENT_TX);
 }
 
 /* If we have a gap in the pending bits, that means we either
-- 
2.17.1