Linux 2.6.39-rc2 build issues

If you happen to end up with this error while building 2.6.39-rc2:

LD [M]  drivers/staging/hv/hv_utils.o
CC [M]  drivers/staging/hv/hv_mouse.o
drivers/staging/hv/hv_mouse.c: In function ‘ReleaseInputDevice’:
drivers/staging/hv/hv_mouse.c:293: error: implicit declaration of function ‘udelay’
make[4]: *** [drivers/staging/hv/hv_mouse.o] Errore 1
make[3]: *** [drivers/staging/hv] Errore 2
make[2]: *** [drivers/staging] Errore 2
make[1]: *** [drivers] Errore 2

you can easily fix it by applying this patch

or by simply adding #include <linux/delay.h> near the top of the file giving the error.