Messages in this thread Patch in this message | | | From | Jia-Ju Bai <> | Subject | [PATCH 2/3] media: dvb-usb: Replace GFP_ATOMIC with GFP_KERNEL in usb_bulk_urb_init | Date | Wed, 11 Apr 2018 11:24:04 +0800 |
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usb_bulk_urb_init() is never called in atomic context.
The call chains ending up at usb_bulk_urb_init() are: [1] usb_bulk_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_bulk_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@gmail.com> --- 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..d6d62e8 100644 --- a/drivers/media/usb/dvb-usb/usb-urb.c +++ b/drivers/media/usb/dvb-usb/usb-urb.c @@ -144,7 +144,7 @@ static int usb_bulk_urb_init(struct usb_data_stream *stream) /* allocate the URBs */ for (i = 0; i < stream->props.count; i++) { - stream->urb_list[i] = usb_alloc_urb(0, GFP_ATOMIC); + stream->urb_list[i] = usb_alloc_urb(0, 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
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