netdev - [PATCH v4 3/6] can: c_can: add a comment about IF

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Date:   Tue,  2 Mar 2021 22:54:32 +0100
From:   Dario Binacchi <dariobin@...ero.it>
To:     linux-kernel@...r.kernel.org
Cc:     Alexander Stein <alexander.stein@...tec-electronic.com>,
        Federico Vaga <federico.vaga@...il.com>,
        Dario Binacchi <dariobin@...ero.it>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        YueHaibing <yuehaibing@...wei.com>,
        Zhang Qilong <zhangqilong3@...wei.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v4 3/6] can: c_can: add a comment about IF_RX interface's use

After reading the commit 640916db2bf7 ("can: c_can: Make it SMP safe")
it may sound strange to see the IF_RX interface used by the
can_inval_tx_object function. A comment was added to avoid any
misunderstanding.

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

---

Changes in v4:
- Restore IF_RX interface.
- Add a comment to clarify why IF_RX interface is used instead of IF_TX.

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

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index dbcc1c1c92d6..6c6d0d0ff7b8 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -732,6 +732,12 @@ static void c_can_do_tx(struct net_device *dev)
 		idx--;
 		pend &= ~(1 << idx);
 		obj = idx + C_CAN_MSG_OBJ_TX_FIRST;
+
+		/*
+		 * We use IF_RX interface instead of IF_TX because we are
+		 * called from c_can_poll(), which runs inside NAPI. We are
+		 * not trasmitting.
+		 */
 		c_can_inval_tx_object(dev, IF_RX, obj);
 		can_get_echo_skb(dev, idx, NULL);
 		bytes += priv->dlc[idx];
-- 
2.17.1