| Message ID | 1521384693-23336-1-git-send-email-baijiaju1990@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Mar 18, 2018 at 10:51:33PM +0800, Jia-Ju Bai wrote: > line6_read_data() is never called in atomic context. > > The call chains ending up at line6_read_data() are: > [1] line6_read_data() <- line6_read_serial_number() -> pod_startup4() > [2] line6_read_data() <- line6_read_serial_number() <- > podhd_startup_workqueue() > [3] line6_read_data() <- podhd_dev_start() <- podhd_startup_workqueue() > [4] line6_read_data() <- line6_read_serial_number() <- toneport_init() > <- line6_probe() > [5] line6_read_data() <- toneport_init() <- line6_probe() > > pod_startup4() and podhd_startup_workqueue() are set in INIT_WORK(). > line6_probe() is called in toneport_probe(), pod_probe(), podhd_probe() > and variax_probe(), which are set as ".probe" in usb_driver structure. > These functions are not called in atomic context. > > Despite never getting called from atomic context, line6_read_data() > calls mdelay for busy wait. > That is not necessary and can be replaced with msleep to > avoid busy waiting. Can we have usleep_range here? Please see Documentation/timers/timers-howto.txt for rationale and range settings. > This is found by a static analysis tool named DCNS written by myself. Here I'm assuming you do not have hardware and do not know how it works, therefore few more people from 'git log --follow sound/usb/line6/driver.c' were added to Cc list. Hopefully they can clarify the right range value. Thank you. > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > sound/usb/line6/driver.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c > index 0ff5a7d..af99e73 100644 > --- a/sound/usb/line6/driver.c > +++ b/sound/usb/line6/driver.c > @@ -356,7 +356,7 @@ int line6_read_data(struct usb_line6 *line6, unsigned address, void *data, > > /* Wait for data length. We'll get 0xff until length arrives. */ > for (count = 0; count < LINE6_READ_WRITE_MAX_RETRIES; count++) { > - mdelay(LINE6_READ_WRITE_STATUS_DELAY); > + msleep(LINE6_READ_WRITE_STATUS_DELAY); > > ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67, > USB_TYPE_VENDOR | USB_RECIP_DEVICE | > -- > 1.9.1 > > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c index 0ff5a7d..af99e73 100644 --- a/sound/usb/line6/driver.c +++ b/sound/usb/line6/driver.c @@ -356,7 +356,7 @@ int line6_read_data(struct usb_line6 *line6, unsigned address, void *data, /* Wait for data length. We'll get 0xff until length arrives. */ for (count = 0; count < LINE6_READ_WRITE_MAX_RETRIES; count++) { - mdelay(LINE6_READ_WRITE_STATUS_DELAY); + msleep(LINE6_READ_WRITE_STATUS_DELAY); ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67, USB_TYPE_VENDOR | USB_RECIP_DEVICE |
line6_read_data() is never called in atomic context. The call chains ending up at line6_read_data() are: [1] line6_read_data() <- line6_read_serial_number() -> pod_startup4() [2] line6_read_data() <- line6_read_serial_number() <- podhd_startup_workqueue() [3] line6_read_data() <- podhd_dev_start() <- podhd_startup_workqueue() [4] line6_read_data() <- line6_read_serial_number() <- toneport_init() <- line6_probe() [5] line6_read_data() <- toneport_init() <- line6_probe() pod_startup4() and podhd_startup_workqueue() are set in INIT_WORK(). line6_probe() is called in toneport_probe(), pod_probe(), podhd_probe() and variax_probe(), which are set as ".probe" in usb_driver structure. These functions are not called in atomic context. Despite never getting called from atomic context, line6_read_data() calls mdelay for busy wait. That is not necessary and can be replaced with msleep to avoid busy waiting. This is found by a static analysis tool named DCNS written by myself. Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> --- sound/usb/line6/driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)