On Thu, Jan 11, 2024 at 9:29 PM Yonghong Song <yonghong.song@xxxxxxxxx> wrote: > > > On 1/11/24 8:59 PM, Alexei Starovoitov wrote: > > On Thu, Jan 11, 2024 at 8:17 PM Yonghong Song <yonghong.song@xxxxxxxxx> wrote: > >> Building the kernel with latest llvm18, I hit the following error: > >> > >> /home/yhs/work/bpf-next/kernel/bpf/verifier.c:4383:13: error: unused function '__is_scalar_unbounded' [-Werror,-Wunused-function] > >> 4383 | static bool __is_scalar_unbounded(struct bpf_reg_state *reg) > >> | ^~~~~~~~~~~~~~~~~~~~~ > >> 1 error generated. > >> > >> Patches [1] and [2] are in the same patch set. Patch [1] removed > >> the usage of __is_scalar_unbounded(), and patch [2] re-introduced > >> the usage of the function. Currently patch [1] is merged into > >> bpf-next while patch [2] does not, hence the above compilation > >> error is triggered. > >> > >> To fix the compilation failure, let us temporarily make > >> __is_scalar_unbounded() not accessible through macro '#if 0'. > >> It can be re-introduced later when [2] is ready to merge. > >> > >> [1] https://lore.kernel.org/bpf/20240108205209.838365-11-maxtram95@xxxxxxxxx/ > >> [2] https://lore.kernel.org/bpf/20240108205209.838365-15-maxtram95@xxxxxxxxx/ > > Ouch. Sorry. This interaction between patches was unexpected. > > Instead of this particular if 0 patch, is there a way to amend pushed > > patches to avoid this issue? > > Another option is that in merged patch [1] removing the function __is_scalar_unbounded(). > And the function can be re-introduced later if needed. Right. That will work, but it's not a tiny function. So it's a code churn to remove it in a commit just to add it back a few commits later. To fix the build I dropped the last two commits, but the issue remains. If they're resend in the same shape later they will re-introduce a bisect issue. Hence the question, how we can tweak the patch "bpf: Track spilled unbounded scalars" so it doesn't leave behind an unused static function.
