> On Sep 19, 2020, at 3:09 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > On Fri, Sep 18, 2020 at 05:16:15PM +0200, Christoph Hellwig wrote: >>> On Fri, Sep 18, 2020 at 02:58:22PM +0100, Al Viro wrote: >>> Said that, why not provide a variant that would take an explicit >>> "is it compat" argument and use it there? And have the normal >>> one pass in_compat_syscall() to that... >> >> That would help to not introduce a regression with this series yes. >> But it wouldn't fix existing bugs when io_uring is used to access >> read or write methods that use in_compat_syscall(). One example that >> I recently ran into is drivers/scsi/sg.c. > > So screw such read/write methods - don't use them with io_uring. > That, BTW, is one of the reasons I'm sceptical about burying the > decisions deep into the callchain - we don't _want_ different > data layouts on read/write depending upon the 32bit vs. 64bit > caller, let alone the pointer-chasing garbage that is /dev/sg. Well, we could remove in_compat_syscall(), etc and instead have an implicit parameter in DEFINE_SYSCALL. Then everything would have to be explicit. This would probably be a win, although it could be quite a bit of work.
