On Wed, May 17, 2017 at 10:01:29AM +0200, Jiri Slaby wrote: > On 05/15/2017, 03:16 PM, Will Deacon wrote: > > Whilst I think this is a good idea, the code in question actually results > > in undefined behaviour per the C spec and is reported by UBSAN. > > Hi, yes, I know -- this patch was the 1st from the series of 3 which I > sent a long time ago to fix that up too. But I remember your patch, so I > sent only this one this time. > > > See my > > patch fixing arm64 here (which I'd forgotten about): > > > > https://www.spinics.net/lists/linux-arch/msg38564.html > > > > But, as stated in the thread above, I think we should go a step further > > and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't > > appear to be used by userspace, and this whole thing is a total mess. > > > > Any thoughts? > > Ok, I am all for that. I think the only question is who is going to do > the work and submit it :)? Do I understand correctly to eliminate all > these functions and the path into the kernel? But won't this break API > -- are there really no users of this interface? That's the million-dollar question, really. I don't know of any code using it, and I couldn't find any when I looked (also nothing reported by Debian Codesearch afaict), but I was hoping linux-arch might have some thoughts on this too. For now, I'll queue my arm64 patch before I forget about it again! Will
