@@ -117,7 +117,7 @@ static int usb_allocate_stream_buffers(struct usb_data_stream *stream, int num,
for (stream->buf_num = 0; stream->buf_num < num; stream->buf_num++) {
deb_mem("allocating buffer %d\n",stream->buf_num);
if (( stream->buf_list[stream->buf_num] =
- usb_alloc_coherent(stream->udev, size, GFP_ATOMIC,
+ usb_alloc_coherent(stream->udev, size, GFP_KERNEL,
&stream->dma_addr[stream->buf_num]) ) == NULL) {
deb_mem("not enough memory for urb-buffer allocation.\n");
usb_free_stream_buffers(stream);
usb_allocate_stream_buffers() is never called in atomic context. The call chains ending up at usb_allocate_stream_buffers() are: [1] usb_allocate_stream_buffers() <- 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() [2] usb_allocate_stream_buffers() <- 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_allocate_stream_buffers() calls usb_alloc_coherent() 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(-)