[PATCH V2] i2c-imx: do not allow interruptions when waiting for I2C to complete

[PATCH V2] i2c-imx: do not allow interruptions when waiting for I2C to complete

[Marc Kleine-Budde]

The i2c_imx_trx_complete() function is using
wait_event_interruptible_timeout() to wait for the I2C controller to
signal that it has completed an I2C bus operation. If the process that
causes the I2C operation receives a signal, the wait will be
interrupted, returning an error. It is better to let the I2C operation
finished before handling the signal (i.e. returning into userspace).

It is safe to use wait_event_timeout() instead, because the timeout
will allow the process to exit if the I2C bus hangs. It's also better
to allow the I2C operation to finish, because unacknowledged I2C
operations can cause the I2C bus to hang.

Signed-off-by: Marc Kleine-Budde <mkl-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Reviewed-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---

V2: Remove check for "result < 0" as commented by Wolfram Sang.

 drivers/i2c/busses/i2c-imx.c |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index d1ff940..58df809 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -161,13 +161,10 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
 {
 	int result;
 
-	result = wait_event_interruptible_timeout(i2c_imx->queue,
+	result = wait_event_timeout(i2c_imx->queue,
 		i2c_imx->i2csr & I2SR_IIF, HZ / 10);
 
-	if (unlikely(result < 0)) {
-		dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
-		return result;
-	} else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
+	if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
 		return -ETIMEDOUT;
 	}
@@ -295,7 +292,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
 		i2c_imx->i2csr = temp;
 		temp &= ~I2SR_IIF;
 		writeb(temp, i2c_imx->base + IMX_I2C_I2SR);
-		wake_up_interruptible(&i2c_imx->queue);
+		wake_up(&i2c_imx->queue);
 		return IRQ_HANDLED;
 	}
 
-- 
1.7.1

Re: [PATCH V2] i2c-imx: do not allow interruptions when waiting for I2C to complete

[Marc Kleine-Budde]

[-- Attachment #1.1: Type: text/plain, Size: 2438 bytes --]

Marc Kleine-Budde wrote:
> The i2c_imx_trx_complete() function is using
> wait_event_interruptible_timeout() to wait for the I2C controller to
> signal that it has completed an I2C bus operation. If the process that
> causes the I2C operation receives a signal, the wait will be
> interrupted, returning an error. It is better to let the I2C operation
> finished before handling the signal (i.e. returning into userspace).
> 
> It is safe to use wait_event_timeout() instead, because the timeout
> will allow the process to exit if the I2C bus hangs. It's also better
> to allow the I2C operation to finish, because unacknowledged I2C
> operations can cause the I2C bus to hang.

Ping, can someone please comment the patch and/or push upstream.

Marc
> 
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
> ---
> 
> V2: Remove check for "result < 0" as commented by Wolfram Sang.
> 
>  drivers/i2c/busses/i2c-imx.c |    9 +++------
>  1 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index d1ff940..58df809 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -161,13 +161,10 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
>  {
>  	int result;
>  
> -	result = wait_event_interruptible_timeout(i2c_imx->queue,
> +	result = wait_event_timeout(i2c_imx->queue,
>  		i2c_imx->i2csr & I2SR_IIF, HZ / 10);
>  
> -	if (unlikely(result < 0)) {
> -		dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
> -		return result;
> -	} else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
> +	if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
>  		dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
>  		return -ETIMEDOUT;
>  	}
> @@ -295,7 +292,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
>  		i2c_imx->i2csr = temp;
>  		temp &= ~I2SR_IIF;
>  		writeb(temp, i2c_imx->base + IMX_I2C_I2SR);
> -		wake_up_interruptible(&i2c_imx->queue);
> +		wake_up(&i2c_imx->queue);
>  		return IRQ_HANDLED;
>  	}
>  


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


[-- Attachment #1.2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 260 bytes --]

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel