[PATCH] bluetooth: hci_ll: Replace mdelay with msleep in download_firmware

[PATCH] bluetooth: hci_ll: Replace mdelay with msleep in download_firmware

[Jia-Ju Bai]

download_firmware() is never called from atomic context.

It is only called by ll_setup() that is called only via function pointer 
"->setup" used in hci_uart_setup() in drivers/bluetooth/hci_serdev.c and
drivers/bluetooth/hci_ldisc.c. hci_uart_setup() is called only 
via function pointer "->setup" used in hci_dev_do_open() 
in net/bluetooth/hci_core.c.
All of the above functions do not enter atomic context.

Besides, ll_setup() calls msleep() and hci_dev_do_open calls mutex_lock().
So it indicates that all the above functions call functions that can sleep.

Despite never getting called from atomic context, download_firmware() 
calls mdelay() for busy wait.
That is not necessary and can be replaced with msleep to avoid busy wait.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 drivers/bluetooth/hci_ll.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bluetooth/hci_ll.c b/drivers/bluetooth/hci_ll.c
index e2c078d..f804adc 100644
--- a/drivers/bluetooth/hci_ll.c
+++ b/drivers/bluetooth/hci_ll.c
@@ -644,7 +644,7 @@ static int download_firmware(struct ll_device *lldev)
 			break;
 		case ACTION_DELAY:	/* sleep */
 			bt_dev_info(lldev->hu.hdev, "sleep command in scr");
-			mdelay(((struct bts_action_delay *)action_ptr)->msec);
+			msleep(((struct bts_action_delay *)action_ptr)->msec);
 			break;
 		}
 		len -= (sizeof(struct bts_action) +
-- 
1.7.9.5

Re: [PATCH] bluetooth: hci_ll: Replace mdelay with msleep in download_firmware

[Marcel Holtmann]

Hi Jia-Ju,

> download_firmware() is never called from atomic context.
> 
> It is only called by ll_setup() that is called only via function pointer 
> "->setup" used in hci_uart_setup() in drivers/bluetooth/hci_serdev.c and
> drivers/bluetooth/hci_ldisc.c. hci_uart_setup() is called only 
> via function pointer "->setup" used in hci_dev_do_open() 
> in net/bluetooth/hci_core.c.
> All of the above functions do not enter atomic context.
> 
> Besides, ll_setup() calls msleep() and hci_dev_do_open calls mutex_lock().
> So it indicates that all the above functions call functions that can sleep.
> 
> Despite never getting called from atomic context, download_firmware() 
> calls mdelay() for busy wait.
> That is not necessary and can be replaced with msleep to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
> drivers/bluetooth/hci_ll.c |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel