Messages in this thread | | | Date | Wed, 13 Mar 2024 13:45:50 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] tracing: Use strcmp() in __assign_str() WARN_ON() check |
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On Wed, 13 Mar 2024 09:59:03 -0700 Nathan Chancellor <nathan@kernel.org> wrote:
> > Reported-by: kernel test robot <lkp@intel.com> > > Closes: https://lore.kernel.org/oe-kbuild-all/202402292111.KIdExylU-lkp@intel.com/ > > Fixes: 433e1d88a3be ("tracing: Add warning if string in __assign_str() does not match __string()") > > Is this change destined for 6.9 or 6.10? I applied it to current > trace/core (eb1533d156d3) along with 51270d573a8d but the warning is > still present. I even tried > > __builtin_choose_expr(__is_constexpr((src)), > strcmp((src), __data_offsets.dst##_ptr_), > (src) != __data_offsets.dst##_ptr_)); > > but not even that silenced the warning. I think we will still need a > diag directive to fully silence this warning.
Yes, you said that the warning is still there, but the bug it shows should not be.
I believe that's because clang still evaluates the (src) != ... even when the source is a contast and it warns about it. But if src is a constant, we do not want to do the !=, we want to do the slower strcmp().
Let me test to make sure that when src is a string "like this" that it does the strcmp(). Otherwise, we may have to always do the strcmp(), which I really would like to avoid.
BTW, I triggered another bug with strcmp():
https://lore.kernel.org/all/20240313093454.3909afe7@gandalf.local.home/
-- Steve
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