2018-07-23 03:38:51

by Jia-Ju Bai

Subject: [PATCH] bluetooth: btusb: Replace GFP_ATOMIC with GFP_KERNEL in inject_cmd_complete()

inject_cmd_complete() is only called by btusb_send_frame_intel(),
which is set to hdev->send, and hdev->send() is never
called in atomic context.

inject_cmd_complete() calls bt_skb_alloc() with GFP_ATOMIC,
which is not necessary.
GFP_ATOMIC can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.
I also manually check the kernel code before reporting it.

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

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index c8c8b0b8d333..1586c54a01f1 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -1870,7 +1870,7 @@ static int inject_cmd_complete(struct hci_dev *hdev, __u16 opcode)
struct hci_event_hdr *hdr;
struct hci_ev_cmd_complete *evt;

- skb = bt_skb_alloc(sizeof(*hdr) + sizeof(*evt) + 1, GFP_ATOMIC);
+ skb = bt_skb_alloc(sizeof(*hdr) + sizeof(*evt) + 1, GFP_KERNEL);
if (!skb)
return -ENOMEM;

--
2.17.0

2018-07-23 16:05:55

by Marcel Holtmann

Subject: Re: [PATCH] bluetooth: btusb: Replace GFP_ATOMIC with GFP_KERNEL in inject_cmd_complete()

Hi Jia-Ju,

> inject_cmd_complete() is only called by btusb_send_frame_intel(),
> which is set to hdev->send, and hdev->send() is never
> called in atomic context.
>
> inject_cmd_complete() calls bt_skb_alloc() with GFP_ATOMIC,
> which is not necessary.
> GFP_ATOMIC can be replaced with GFP_KERNEL.
>
> This is found by a static analysis tool named DCNS written by myself.
> I also manually check the kernel code before reporting it.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/bluetooth/btusb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

all 6 patches have been applied to bluetooth-next tree.

Regards

Marcel