Defined in 2 files as a macro:

• include/uapi/linux/if_tun.h, line 39 (as a macro)
• tools/include/uapi/linux/if_tun.h, line 39 (as a macro)

Referenced in 3 files:

• arch/um/drivers/vector_user.c, line 589
• drivers/net/tap.c, line 968
• drivers/net/tun.c, line 3203