From 2871edb32f4622c3a25ce4b3977bad9050b91974 Mon Sep 17 00:00:00 2001
From: Anssi Hannula <anssi.hannula@bitwise.fi>
Date: Mon, 10 Oct 2022 20:52:27 +0200
Subject: [PATCH] can: kvaser_usb: Fix possible completions during init_completion
Git-commit: 2871edb32f4622c3a25ce4b3977bad9050b91974
Patch-mainline: v6.1-rc3
References: git-fixes

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")
Tested-by: Jimmy Assarsson <extja@kvaser.com>
Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Link: https://lore.kernel.org/all/20221010185237.319219-2-extja@kvaser.com
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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 7b52fda73d82..66f672ea631b 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
@@ -1875,7 +1875,7 @@ 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);
@@ -1893,7 +1893,7 @@ 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 50f2ac8319ff..19958037720f 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
@@ -1320,7 +1320,7 @@ 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);
@@ -1338,7 +1338,7 @@ 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);
-- 
2.35.3