On 8/26/19 5:54 AM, Rasmus Villemoes wrote:
Hi, uapi/linux/watchdog.h has these #define WDIOC_SETOPTIONS _IOR(WATCHDOG_IOCTL_BASE, 4, int) This is a write from userspace perspective, so should have been _IOW. #define WDIOC_KEEPALIVE _IOR(WATCHDOG_IOCTL_BASE, 5, int) This one doesn't actually take an argument, so should just have been an _IO - or if anything, an _IOW. One could be misled to think that if the int argument has 'V' somewhere (perhaps first or last byte, depending on endianness) that would count as a magic close. #define WDIOC_SETTIMEOUT _IOWR(WATCHDOG_IOCTL_BASE, 6, int) #define WDIOC_SETPRETIMEOUT _IOWR(WATCHDOG_IOCTL_BASE, 8, int) The SETTIMEOUT handling does fall through to the GETTIMEOUT case, so that one is indeed a "write this, but tell me what value actually took effect". The SETPRETIMEOUT case ends with a break, so that one is really _IOW. There's not much to do about these, I think, but perhaps one could add a comment to the uapi header containing the magic explains-all phrase "historical reasons".
Those ioctls were imported into git when the git repository was created. I don't think it is worth bothering about it now. I also don't think it would add much if any value to add "historic reason" comments. Guenter
