diff mbox

dma: at_hdmac: fix invalid remaining bytes detection

Message ID 1406887406-10567-1-git-send-email-alexandre.belloni@free-electrons.com (mailing list archive)
State Rejected
Headers show

Commit Message

Alexandre Belloni Aug. 1, 2014, 10:03 a.m. UTC 
Found using smatch:
drivers/dma/at_hdmac.c:299 atc_get_bytes_left() warn: unsigned
'atchan->remain_desc' is never less than zero.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
 drivers/dma/at_hdmac.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

Sergei Shtylyov Aug. 1, 2014, 2:08 p.m. UTC | #1 
Hello.

On 08/01/2014 02:03 PM, Alexandre Belloni wrote:

> Found using smatch:
> drivers/dma/at_hdmac.c:299 atc_get_bytes_left() warn: unsigned
> 'atchan->remain_desc' is never less than zero.

> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
>   drivers/dma/at_hdmac.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)

> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
> index c13a3bb0f594..9ec84ee2fa25 100644
> --- a/drivers/dma/at_hdmac.c
> +++ b/drivers/dma/at_hdmac.c
> @@ -294,14 +294,16 @@ static int atc_get_bytes_left(struct dma_chan *chan)
>   			ret = -EINVAL;
>   			goto out;
>   		}
> -		atchan->remain_desc -= (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
> -						<< (desc_first->tx_width);
> -		if (atchan->remain_desc < 0) {
> +
> +		count = (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
> +			<< (desc_first->tx_width);

    Parens not needed here.

[...]

WBR, Sergei

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diff mbox

Patch

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index c13a3bb0f594..9ec84ee2fa25 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -294,14 +294,16 @@  static int atc_get_bytes_left(struct dma_chan *chan)
 			ret = -EINVAL;
 			goto out;
 		}
-		atchan->remain_desc -= (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
-						<< (desc_first->tx_width);
-		if (atchan->remain_desc < 0) {
+
+		count = (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
+			<< (desc_first->tx_width);
+		if (atchan->remain_desc < count) {
 			ret = -EINVAL;
 			goto out;
-		} else {
-			ret = atchan->remain_desc;
 		}
+
+		atchan->remain_desc -= count;
+		ret = atchan->remain_desc;
 	} else {
 		/*
 		 * Get residual bytes when current