[PATCH wg-linux-can-next devel 1/1] can: cc770: Fix indirect access deadlock on ISA cards

[PATCH wg-linux-can-next devel 1/1] can: cc770: Fix indirect access deadlock on ISA cards

[Wolfgang Zarre]

This fix avoids a deadlock if an interrupt occurs
during consecutive port operations on ISA cards
utilising indirect access via address and data
port.

Tested on a B&R ISA card.

CC: linux-can@vger.kernel.org
CC: netdev@vger.kernel.org
Signed-off-by: Wolfgang Zarre <lkdev@essax.com>
---
 drivers/net/can/cc770/cc770_isa.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/net/can/cc770/cc770_isa.c b/drivers/net/can/cc770/cc770_isa.c
index 4be5fe2..9f3a25c 100644
--- a/drivers/net/can/cc770/cc770_isa.c
+++ b/drivers/net/can/cc770/cc770_isa.c
@@ -110,6 +110,11 @@ MODULE_PARM_DESC(bcr, "Bus configuration register (default=0x40 [CBY])");
 #define CC770_IOSIZE          0x20
 #define CC770_IOSIZE_INDIRECT 0x02
 
+/* Spinlock for cc770_isa_port_write_reg_indirect
+ * and cc770_isa_port_read_reg_indirect
+ */
+static DEFINE_SPINLOCK(cc770_isa_port_lock);
+
 static struct platform_device *cc770_isa_devs[MAXDEV];
 
 static u8 cc770_isa_mem_read_reg(const struct cc770_priv *priv, int reg)
@@ -138,18 +143,27 @@ static u8 cc770_isa_port_read_reg_indirect(const struct cc770_priv *priv,
 					     int reg)
 {
 	unsigned long base = (unsigned long)priv->reg_base;
+	unsigned long flags;
+	u8 val;
 
+	spin_lock_irqsave(&cc770_isa_port_lock, flags);
 	outb(reg, base);
-	return inb(base + 1);
+	val = inb(base + 1);
+	spin_unlock_irqrestore(&cc770_isa_port_lock, flags);
+
+	return val;
 }
 
 static void cc770_isa_port_write_reg_indirect(const struct cc770_priv *priv,
 						int reg, u8 val)
 {
 	unsigned long base = (unsigned long)priv->reg_base;
+	unsigned long flags;
 
+	spin_lock_irqsave(&cc770_isa_port_lock, flags);
 	outb(reg, base);
 	outb(val, base + 1);
+	spin_unlock_irqrestore(&cc770_isa_port_lock, flags);
 }
 
 static int __devinit cc770_isa_probe(struct platform_device *pdev)
-- 
1.7.7.3

Re: [PATCH wg-linux-can-next devel 1/1] can: cc770: Fix indirect access deadlock on ISA cards

[Wolfgang Grandegger]

On 01/15/2012 01:21 PM, Wolfgang Zarre wrote:
> This fix avoids a deadlock if an interrupt occurs
> during consecutive port operations on ISA cards
> utilising indirect access via address and data
> port.
> 
> Tested on a B&R ISA card.
> 
> CC: linux-can@vger.kernel.org
> CC: netdev@vger.kernel.org
> Signed-off-by: Wolfgang Zarre <lkdev@essax.com>

Acked-by: Wolfgang Grandegger <wg@grandegger.com>

Next time, please drop the CC to the old BerliOS Socketcan mailing
lists. Marc, Oliver? Do we, should we, still send patches to the
"netdev@vger.kernel.org" as well.

Wolfgang.

Re: [PATCH wg-linux-can-next devel 1/1] can: cc770: Fix indirect access deadlock on ISA cards

[Wolfgang Zarre]

Hello Wolfgang,

> On 01/15/2012 01:21 PM, Wolfgang Zarre wrote:
>> This fix avoids a deadlock if an interrupt occurs
>> during consecutive port operations on ISA cards
>> utilising indirect access via address and data
>> port.
>>
>> Tested on a B&R ISA card.
>>
>> CC: linux-can@vger.kernel.org
>> CC: netdev@vger.kernel.org
>> Signed-off-by: Wolfgang Zarre<lkdev@essax.com>
>
> Acked-by: Wolfgang Grandegger<wg@grandegger.com>

Thanks.

>
> Next time, please drop the CC to the old BerliOS Socketcan mailing
> lists. Marc, Oliver? Do we, should we, still send patches to the
> "netdev@vger.kernel.org" as well.

Hmmm, actually I dropped to the old BerliOS Socketcan mailing list but
not as CC statement in the email body , however, please let me know
if You prefer to have it there included as well.

Thanks.

>
> Wolfgang.

Re: [PATCH wg-linux-can-next devel 1/1] can: cc770: Fix indirect access deadlock on ISA cards

[Marc Kleine-Budde]

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On 01/15/2012 01:21 PM, Wolfgang Zarre wrote:
> This fix avoids a deadlock if an interrupt occurs
> during consecutive port operations on ISA cards
> utilising indirect access via address and data
> port.
> 
> Tested on a B&R ISA card.
> 
> CC: linux-can@vger.kernel.org
> CC: netdev@vger.kernel.org
> Signed-off-by: Wolfgang Zarre <lkdev@essax.com>

Applied to can-next.
tnx Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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