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[3.8.y.z,extended,stable] Patch "can: c_can: don't call pm_runtime_get_sync() from interrupt context" has been added to staging queue

Message ID 1387570866-19287-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Dec. 20, 2013, 8:21 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    can: c_can: don't call pm_runtime_get_sync() from interrupt context

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.15.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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From 87e47ba3e35988dc43d554f4b9f16c83ecb1bacd Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Sun, 24 Nov 2013 23:31:24 +0100
Subject: can: c_can: don't call pm_runtime_get_sync() from interrupt context

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: Kamal Mostafa <kamal@canonical.com>
---
 drivers/net/can/c_can/c_can.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

--
1.8.3.2
diff mbox

Patch

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 915847d..aa92283 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -709,22 +709,31 @@  static int c_can_set_mode(struct net_device *dev, enum can_mode mode)
 	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;
 }

 /*
@@ -868,7 +877,7 @@  static int c_can_handle_state_change(struct net_device *dev,
 	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;