2018-04-11 02:18:25

by Jia-Ju Bai

Subject: [PATCH] net: ieee802154: atusb: Replace GFP_ATOMIC with GFP_KERNEL in atusb_probe

atusb_probe() is never called in atomic context.
This function is only set as ".probe" in struct usb_driver.

Despite never getting called from atomic context,
atusb_probe() calls usb_alloc_urb() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/net/ieee802154/atusb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ieee802154/atusb.c b/drivers/net/ieee802154/atusb.c
index ef68851..ab6a505 100644
--- a/drivers/net/ieee802154/atusb.c
+++ b/drivers/net/ieee802154/atusb.c
@@ -789,7 +789,7 @@ static int atusb_probe(struct usb_interface *interface,
atusb->tx_dr.bRequest = ATUSB_TX;
atusb->tx_dr.wValue = cpu_to_le16(0);

- atusb->tx_urb = usb_alloc_urb(0, GFP_ATOMIC);
+ atusb->tx_urb = usb_alloc_urb(0, GFP_KERNEL);
if (!atusb->tx_urb)
goto fail;

--
1.9.1

2018-04-12 12:13:23

by Stefan Schmidt

Subject: Re: [PATCH] net: ieee802154: atusb: Replace GFP_ATOMIC with GFP_KERNEL in atusb_probe

Hello.


On 04/11/2018 04:14 AM, Jia-Ju Bai wrote:
> atusb_probe() is never called in atomic context.
> This function is only set as ".probe" in struct usb_driver.
>
> Despite never getting called from atomic context,
> atusb_probe() calls usb_alloc_urb() with GFP_ATOMIC,
> which does not sleep for allocation.
> GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
> which can sleep and improve the possibility of sucessful allocation.
>
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/net/ieee802154/atusb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ieee802154/atusb.c b/drivers/net/ieee802154/atusb.c
> index ef68851..ab6a505 100644
> --- a/drivers/net/ieee802154/atusb.c
> +++ b/drivers/net/ieee802154/atusb.c
> @@ -789,7 +789,7 @@ static int atusb_probe(struct usb_interface *interface,
> atusb->tx_dr.bRequest = ATUSB_TX;
> atusb->tx_dr.wValue = cpu_to_le16(0);
>
> - atusb->tx_urb = usb_alloc_urb(0, GFP_ATOMIC);
> + atusb->tx_urb = usb_alloc_urb(0, GFP_KERNEL);
> if (!atusb->tx_urb)
> goto fail;
>

This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

regards
Stefan Schmidt