[kbuild-all] Re: [ammarfaizi2-block:google/android/kernel/common/android12-5.4 6517/9999] fs/userfaultfd.c:1519:9: warning: variable 'ioctls_out' set but not used

On Wed, Jan 19, 2022 at 1:19 PM Suren Baghdasaryan <surenb(a)google.com&gt; wrote: > > On Wed, Jan 19, 2022 at 12:39 PM Axel Rasmussen > <axelrasmussen(a)google.com&gt; wrote: > > > > Lokesh, I only spent a few moments looking, but my suspicion is that > > this is the result of an incomplete backport of these patches to the > > Android kernel? > > > > The UFFDIO_CONTINUE patches introduced ioctls_out since the > > computation of it got more complicated, and those same patches also > > modified the put_user() on line 1533 here to use ioctls_out. I think > > Android backported the first part, but left out the second? > > The backport https://android-review.googlesource.com/c/kernel/common/+/1652718 > looks like a mixture of > 14819305e09fe4 ("userfaultfd: wp: declare _UFFDIO_WRITEPROTECT > conditionally") and f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE > ioctl"). > Not sure why it was done this way, maybe to minimize code changes > while backporting. > Simplest fix is probably to add __maybe_unused to ioctls_out declaration. Unfortunately, that doesn't quite do it. That would fix the warning, but the code in the original e-mail is still wrong: we incorrectly don't report the _UFFDIO_CONTINUE bit, unless we use the value we computed in ioctls_out.