2018-01-27 10:13:58

by Jia-Ju Bai

Subject: [PATCH] bluetooth: hci_ath: Replace mdelay with msleep in ath_wakeup_ar3k

ath_wakeup_ar3k() is never called from atomic context.

It is only called by ath_hci_uart_work() that is only called in
ath_open() via INIT_WORK().
All of the above functions do not enter atomic context along the way.

Despite never getting called from atomic context, ath_wakeup_ar3k() 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 <[email protected]>
---
drivers/bluetooth/hci_ath.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_ath.c b/drivers/bluetooth/hci_ath.c
index 14ae7ee..d568fbd 100644
--- a/drivers/bluetooth/hci_ath.c
+++ b/drivers/bluetooth/hci_ath.c
@@ -71,12 +71,12 @@ static int ath_wakeup_ar3k(struct tty_struct *tty)
/* Clear RTS first */
tty->driver->ops->tiocmget(tty);
tty->driver->ops->tiocmset(tty, 0x00, TIOCM_RTS);
- mdelay(20);
+ msleep(20);

/* Set RTS, wake up board */
tty->driver->ops->tiocmget(tty);
tty->driver->ops->tiocmset(tty, TIOCM_RTS, 0x00);
- mdelay(20);
+ msleep(20);

status = tty->driver->ops->tiocmget(tty);
return status;
--
1.7.9.5

2018-02-07 08:58:45

by Marcel Holtmann

Subject: Re: [PATCH] bluetooth: hci_ath: Replace mdelay with msleep in ath_wakeup_ar3k

Hi Jia-Ju,

> ath_wakeup_ar3k() is never called from atomic context.
>
> It is only called by ath_hci_uart_work() that is only called in
> ath_open() via INIT_WORK().
> All of the above functions do not enter atomic context along the way.
>
> Despite never getting called from atomic context, ath_wakeup_ar3k() 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 <[email protected]>
> ---
> drivers/bluetooth/hci_ath.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel