usb_isoc_urb_init() is never called in atomic context.
The call chains ending up at usb_isoc_urb_init() are:
[1] usb_isoc_urb_init() <- usb_urb_init()
<- dvb_usb_adapter_stream_init() <- dvb_usb_adapter_init
<- dvb_usb_init() <- dvb_usb_device_init() <- xxx_probe()
xxx_probe including ttusb2_probe, vp7045_usb_probe, a800_probe, and so on.
These xxx_probe() functions are set as ".probe" in struct usb_driver.
And these functions are not called in atomic context.
Despite never getting called from atomic context,
usb_isoc_urb_init() calls usb_alloc_urb() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.
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@xxxxxxxxx>
---
drivers/media/usb/dvb-usb/usb-urb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/usb/dvb-usb/usb-urb.c b/drivers/media/usb/dvb-usb/usb-urb.c
index 8917360..1efa4bd5 100644
--- a/drivers/media/usb/dvb-usb/usb-urb.c
+++ b/drivers/media/usb/dvb-usb/usb-urb.c
@@ -177,7 +177,7 @@ static int usb_isoc_urb_init(struct usb_data_stream *stream)
struct urb *urb;
int frame_offset = 0;
- stream->urb_list[i] = usb_alloc_urb(stream->props.u.isoc.framesperurb, GFP_ATOMIC);
+ stream->urb_list[i] = usb_alloc_urb(stream->props.u.isoc.framesperurb, GFP_KERNEL);
if (!stream->urb_list[i]) {
deb_mem("not enough memory for urb_alloc_urb!\n");
for (j = 0; j < i; j++)
--
1.9.1
