linux-kernel - [PATCH 03/12] can: kvaser_usb: Fix possible completions during init

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Message-Id: <20220516134748.3724796-4-anssi.hannula@bitwise.fi>
Date:   Mon, 16 May 2022 16:47:39 +0300
From:   Anssi Hannula <anssi.hannula@...wise.fi>
To:     Jimmy Assarsson <extja@...ser.com>
Cc:     linux-can@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 03/12] can: kvaser_usb: Fix possible completions during init_completion

kvaser_usb uses completions to signal when a response event is received
for outgoing commands.

However, it uses init_completion() to reinitialize the start_comp and
stop_comp completions before sending the start/stop commands.

In case the device sends the corresponding response just before the
actual command is sent, complete() may be called concurrently with
init_completion() which is not safe.

This might be triggerable even with a properly functioning device by
stopping the interface (CMD_STOP_CHIP) just after it goes bus-off (which
also causes the driver to send CMD_STOP_CHIP when restart-ms is off),
but that was not tested.

Fix the issue by using reinit_completion() instead.

Fixes: 080f40a6fa28 ("can: kvaser_usb: Add support for Kvaser CAN/USB devices")
Signed-off-by: Anssi Hannula <anssi.hannula@...wise.fi>
---
 drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c | 4 ++--
 drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
index 4e90a4b7f95a..b0094f162964 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
@@ -1869,7 +1869,7 @@ static int kvaser_usb_hydra_start_chip(struct kvaser_usb_net_priv *priv)
 {
 	int err;
 
-	init_completion(&priv->start_comp);
+	reinit_completion(&priv->start_comp);
 
 	err = kvaser_usb_hydra_send_simple_cmd(priv->dev, CMD_START_CHIP_REQ,
 					       priv->channel);
@@ -1887,7 +1887,7 @@ static int kvaser_usb_hydra_stop_chip(struct kvaser_usb_net_priv *priv)
 {
 	int err;
 
-	init_completion(&priv->stop_comp);
+	reinit_completion(&priv->stop_comp);
 
 	/* Make sure we do not report invalid BUS_OFF from CMD_CHIP_STATE_EVENT
 	 * see comment in kvaser_usb_hydra_update_state()
diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
index d9f40b9702a5..09ade66256b2 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
@@ -1300,7 +1300,7 @@ static int kvaser_usb_leaf_start_chip(struct kvaser_usb_net_priv *priv)
 {
 	int err;
 
-	init_completion(&priv->start_comp);
+	reinit_completion(&priv->start_comp);
 
 	err = kvaser_usb_leaf_send_simple_cmd(priv->dev, CMD_START_CHIP,
 					      priv->channel);
@@ -1318,7 +1318,7 @@ static int kvaser_usb_leaf_stop_chip(struct kvaser_usb_net_priv *priv)
 {
 	int err;
 
-	init_completion(&priv->stop_comp);
+	reinit_completion(&priv->stop_comp);
 
 	err = kvaser_usb_leaf_send_simple_cmd(priv->dev, CMD_STOP_CHIP,
 					      priv->channel);
-- 
2.34.1