On Wed, Jan 27, 2016 at 10:47:37PM +0000, Mathieu Desnoyers wrote: > ----- On Jan 27, 2016, at 5:11 PM, Josh Triplett [email protected] wrote: > > > On Wed, Jan 27, 2016 at 09:34:35PM +0000, Mathieu Desnoyers wrote: > >> ----- On Jan 27, 2016, at 12:37 PM, Thomas Gleixner [email protected] > >> wrote: > >> > >> > On Wed, 27 Jan 2016, Thomas Gleixner wrote: > >> > > >> >> On Wed, 27 Jan 2016, Mathieu Desnoyers wrote: > >> >> > ----- On Jan 27, 2016, at 12:22 PM, Thomas Gleixner > >> >> > [email protected] wrote: > >> >> > Sounds fair. What is the recommended typing for "ptr" then ? > >> >> > uint32_t ** or uint32_t * ? > >> >> > > >> >> > It would be expected to pass a "uint32_t *" for the set > >> >> > operation, but the "get" operation requires a "uint32_t **". > >> >> > >> >> Well, you can't change the types depending on the opcode, so you need > >> >> to stick > >> >> with **. > >> > > >> > Alternatively you make it: > >> > > >> > (opcode, *newptr, **oldptr, flags); > >> > >> I'm tempted to stick to (opcode, **ptr, flags), because > >> other syscalls that have "*newptr", "**oldptr" > >> typically have them because they save the current state > >> into oldptr, and set the new state, which is really > >> not the case here. To eliminate any risk of confusion, > >> I am tempted to keep a single "**ptr". > >> > >> Unless someone has a better idea... > > > > Either that or you could define it as "void *" and interpret it based on > > flags, but that seems unfortunate; let's not imitate ioctl-style > > typeless parameters. I'd stick with the double pointer and the current > > behavior. > > Allright, will do! Thanks for the feedback :)
Please don't forget that you also need to implement compat handling since the size of the pointer that is being pointed to is only four bytes for compat tasks.
