pub const USB_DISK_ABSENT: i64 = -21;Expand description
No USB disk is attached - the opposite instruction to USB_DISK_BUSY, and it must stay in step with
the kernel’s USB_DISK_ABSENT. BUSY means “come back, I am working”; ABSENT means “there is nothing
here, and asking again cannot change that - only a hot-plug can”. A caller that retries on this waits
out its entire budget against an empty socket and then reports the device as busy, which is a false
statement about hardware sitting on the operator’s desk.