[PATCH 3.12 29/62] can: c_can: dont call pm_runtime_get_sync() from interrupt context

Greg Kroah-Hartman
2013-12-10T08:04:58Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

commit e35d46adc49b469fd92bdb64fea8af93640e6651 upstream.

The c_can driver contians a callpath (c_can_poll -> c_can_state_change ->
c_can_get_berr_counter) which may call pm_runtime_get_sync() from the IRQ
handler, which is not allowed and results in "BUG: scheduling while atomic".

This problem is fixed by introducing __c_can_get_berr_counter, which will not
call pm_runtime_get_sync().

Reported-by: Andrew Glen <AGlen@bepmarine.com>
Tested-by: Andrew Glen <AGlen@bepmarine.com>
Signed-off-by: Andrew Glen <AGlen@bepmarine.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/can/c_can/c_can.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -712,22 +712,31 @@ static int c_can_set_mode(struct net_dev
return 0;
}

-static int c_can_get_berr_counter(const struct net_device *dev,
- struct can_berr_counter *bec)
+static int __c_can_get_berr_counter(const struct net_device *dev,
+ struct can_berr_counter *bec)
{
unsigned int reg_err_counter;
struct c_can_priv *priv = netdev_priv(dev);

- c_can_pm_runtime_get_sync(priv);
-
reg_err_counter = priv->read_reg(priv, C_CAN_ERR_CNT_REG);
bec->rxerr = (reg_err_counter & ERR_CNT_REC_MASK) >>
ERR_CNT_REC_SHIFT;
bec->txerr = reg_err_counter & ERR_CNT_TEC_MASK;

+ return 0;
+}
+
+static int c_can_get_berr_counter(const struct net_device *dev,
+ struct can_berr_counter *bec)
+{
+ struct c_can_priv *priv = netdev_priv(dev);
+ int err;
+
+ c_can_pm_runtime_get_sync(priv);
+ err = __c_can_get_berr_counter(dev, bec);
c_can_pm_runtime_put_sync(priv);

- return 0;
+ return err;
}

/*
@@ -872,7 +881,7 @@ static int c_can_handle_state_change(str
if (unlikely(!skb))
return 0;

- c_can_get_berr_counter(dev, &bec);
+ __c_can_get_berr_counter(dev, &bec);
reg_err_counter = priv->read_reg(priv, C_CAN_ERR_CNT_REG);
rx_err_passive = (reg_err_counter & ERR_CNT_RP_MASK) >>
ERR_CNT_RP_SHIFT;