[PATCH] drivers/net: Fix potential incorrect call for udelay()

[PATCH] drivers/net: Fix potential incorrect call for udelay()

[Libin]

From: Li Bin <huawei.libin@huawei.com>

The variable delay_time as a module parameter can be set a value
exceeding the limit of the udelay function. This patch checks the
delay_time value to select mdelay() or udelay().

Signed-off-by: Li Bin <huawei.libin@huawei.com>
---
 drivers/net/ethernet/8390/pcnet_cs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/8390/pcnet_cs.c b/drivers/net/ethernet/8390/pcnet_cs.c
index 46c5aad..29fe157 100644
--- a/drivers/net/ethernet/8390/pcnet_cs.c
+++ b/drivers/net/ethernet/8390/pcnet_cs.c
@@ -1284,8 +1284,12 @@ static void dma_block_output(struct net_device *dev, int count,
 	}
 
     outb_p(ENISR_RDC, nic_base + EN0_ISR);	/* Ack intr. */
-    if (info->flags & DELAY_OUTPUT)
-	udelay((long)delay_time);
+    if (info->flags & DELAY_OUTPUT) {
+		if (delay_time >= 1000)
+			mdelay((long)delay_time/1000);
+		else
+			udelay(delay_time);
+	}
     ei_status.dmaing &= ~0x01;
 }
 
-- 
1.8.2.2

Re: [PATCH] drivers/net: Fix potential incorrect call for udelay()

[One Thousand Gnomes]

On Mon, 23 Dec 2013 17:33:44 +0800
Libin <huawei.libin@huawei.com> wrote:

> From: Li Bin <huawei.libin@huawei.com>
> 
> The variable delay_time as a module parameter can be set a value
> exceeding the limit of the udelay function. This patch checks the
> delay_time value to select mdelay() or udelay().
> 
> Signed-off-by: Li Bin <huawei.libin@huawei.com>

Nobody should need to set a delay time that long, so this seems a rather
surplus check.

Alan

Re: [PATCH] drivers/net: Fix potential incorrect call for udelay()

[tingwei liu]

On Mon, Dec 23, 2013 at 5:33 PM, Libin <huawei.libin@huawei.com> wrote:
>
> From: Li Bin <huawei.libin@huawei.com>
>
> The variable delay_time as a module parameter can be set a value
> exceeding the limit of the udelay function. This patch checks the
> delay_time value to select mdelay() or udelay().
>
> Signed-off-by: Li Bin <huawei.libin@huawei.com>
> ---
>  drivers/net/ethernet/8390/pcnet_cs.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/8390/pcnet_cs.c b/drivers/net/ethernet/8390/pcnet_cs.c
> index 46c5aad..29fe157 100644
> --- a/drivers/net/ethernet/8390/pcnet_cs.c
> +++ b/drivers/net/ethernet/8390/pcnet_cs.c
> @@ -1284,8 +1284,12 @@ static void dma_block_output(struct net_device *dev, int count,
>         }
>
>      outb_p(ENISR_RDC, nic_base + EN0_ISR);     /* Ack intr. */
> -    if (info->flags & DELAY_OUTPUT)
> -       udelay((long)delay_time);
> +    if (info->flags & DELAY_OUTPUT) {
> +               if (delay_time >= 1000)
> +                       mdelay((long)delay_time/1000);

Indeed use of mdelay is discouraged.
I prefer to limit delay_time less than 1000.

Tingwei
>
> +               else
> +                       udelay(delay_time);
> +       }
>      ei_status.dmaing &= ~0x01;
>  }
>
> --
> 1.8.2.2
>
>
> --
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