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can: m_can: m_can_tx_work_queue(): fix tx_skb race condition

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[ Upstream commit e04b2cfe61 ]

The m_can_start_xmit() function checks if the cdev->tx_skb is NULL and
returns with NETDEV_TX_BUSY in case tx_sbk is not NULL.

There is a race condition in the m_can_tx_work_queue(), where first
the skb is send to the driver and then the case tx_sbk is set to NULL.
A TX complete IRQ might come in between and wake the queue, which
results in tx_skb not being cleared yet.

Fixes: f524f829b7 ("can: m_can: Create a m_can platform framework")
Tested-by: Torin Cooper-Bennun <torin@maxiluxsystems.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Marc Kleine-Budde 2021-05-05 13:32:27 +02:00 • committed by Greg Kroah-Hartman
commit 26359d362c
1 changed files with 2 additions and 1 deletions
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3
drivers/net/can/m_can/m_can.c
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@ -1466,6 +1466,8 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
int i;
int putidx;
cdev->tx_skb = NULL;
/* Generate ID field for TX buffer Element */
/* Common to all supported M_CAN versions */
if (cf->can_id & CAN_EFF_FLAG) {
@ -1582,7 +1584,6 @@ static void m_can_tx_work_queue(struct work_struct *ws)
tx_work);
m_can_tx_handler(cdev);
cdev->tx_skb = NULL;
}
static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,