This is a note to let you know that I've just added the patch titled
can: c_can: fix an interrupt thrash issue with c_can driver
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
can-c_can-fix-an-interrupt-thrash-issue-with-c_can-driver.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 148c87c89e1a8863d3d965179f3ab1a06490569e Mon Sep 17 00:00:00 2001
From: AnilKumar Ch <[email protected]>
Date: Wed, 23 May 2012 17:45:10 +0530
Subject: can: c_can: fix an interrupt thrash issue with c_can driver
From: AnilKumar Ch <[email protected]>
commit 148c87c89e1a8863d3d965179f3ab1a06490569e upstream.
This patch fixes an interrupt thrash issue with c_can driver.
In c_can_isr() function interrupts are disabled and enabled only in
c_can_poll() function. c_can_isr() & c_can_poll() both read the
irqstatus flag. However, irqstatus is always read as 0 in c_can_poll()
because all C_CAN interrupts are disabled in c_can_isr(). This causes
all interrupts to be re-enabled in c_can_poll() which in turn causes
another interrupt since the event is not really handled. This keeps
happening causing a flood of interrupts.
To fix this, read the irqstatus register in isr and use the same cached
value in the poll function.
Signed-off-by: AnilKumar Ch <[email protected]>
Acked-by: Wolfgang Grandegger <[email protected]>
Signed-off-by: Marc Kleine-Budde <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/net/can/c_can/c_can.c | 7 +++----
drivers/net/can/c_can/c_can.h | 1 +
2 files changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -952,7 +952,7 @@ static int c_can_poll(struct napi_struct
struct net_device *dev = napi->dev;
struct c_can_priv *priv = netdev_priv(dev);
- irqstatus = priv->read_reg(priv, &priv->regs->interrupt);
+ irqstatus = priv->irqstatus;
if (!irqstatus)
goto end;
@@ -1030,12 +1030,11 @@ end:
static irqreturn_t c_can_isr(int irq, void *dev_id)
{
- u16 irqstatus;
struct net_device *dev = (struct net_device *)dev_id;
struct c_can_priv *priv = netdev_priv(dev);
- irqstatus = priv->read_reg(priv, &priv->regs->interrupt);
- if (!irqstatus)
+ priv->irqstatus = priv->read_reg(priv, &priv->regs->interrupt);
+ if (!priv->irqstatus)
return IRQ_NONE;
/* disable all interrupts and schedule the NAPI */
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
@@ -76,6 +76,7 @@ struct c_can_priv {
unsigned int tx_next;
unsigned int tx_echo;
void *priv; /* for board-specific data */
+ u16 irqstatus;
};
struct net_device *alloc_c_can_dev(void);
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/can-c_can-fix-bug-echo_skb-is-occupied-during-transmit.patch
queue-3.4/can-c_can-fix-race-condition-in-c_can_open.patch
queue-3.4/can-c_can-fix-an-interrupt-thrash-issue-with-c_can-driver.patch
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