Re: [PATCH 1/2] staging: irda: Replace mdelay with usleep_range in stir421x_fw_upload

Johan Hovold
2018-04-11T07:07:42Z

On Wed, Apr 11, 2018 at 09:29:34AM +0800, Jia-Ju Bai wrote:
> stir421x_fw_upload() is never called in atomic context.
>
> The call chain ending up at stir421x_fw_upload() is:
> [1] stir421x_fw_upload() <- stir421x_patch_device() <- irda_usb_probe()
>
> irda_usb_probe() is set as ".probe" in struct usb_driver.
> This function is not called in atomic context.
>
> Despite never getting called from atomic context, stir421x_fw_upload()
> calls mdelay() to busily wait.
> This is not necessary and can be replaced with usleep_range() to
> avoid busy waiting.
>
> 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 <baijiaju1990@gmail.com>

This all looks good (also note the call to usb_control_msg(), which may
sleep, just above the mdelay()).

Reviewed-by: Johan Hovold <johan@kernel.org>

Thanks,
Johan