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Date:   Mon, 23 May 2022 12:54:06 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Alexander Popov <alex.popov@linux.com>,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        Masahiro Yamada <masahiroy@kernel.org>,
        linux-kbuild@vger.kernel.org
Subject: Re: [PATCH] gcc-plugins: Change all version strings match kernel
Message-ID: <202205231251.39D012E@keescook>
References: <20220510235412.3627034-1-keescook@chromium.org>
 <20220523143054.GA3164771@roeck-us.net>
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On Mon, May 23, 2022 at 07:30:54AM -0700, Guenter Roeck wrote:
> On Tue, May 10, 2022 at 04:54:12PM -0700, Kees Cook wrote:
> > It's not meaningful for the GCC plugins to track their versions separately
> > from the rest of the kernel. Switch all versions to the kernel version.
> > 
> > Fix mismatched indenting while we're at it.
> > 
> > Cc: linux-hardening@vger.kernel.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> I see random build failures with this patch in linux-next.
> 
> Error log:
> cc1plus: fatal error: ./include/generated/utsrelease.h: No such file or directory
> 
> The problem doesn't happen all the time. Is there some missing dependency ?

Here's a prior report I hadn't been able to repro:
https://lore.kernel.org/linux-mm/202205230239.EZxeZ3Fv-lkp@intel.com

But now I can: I see it with a -j1 build. This fixes it for me:

diff --git a/Makefile b/Makefile
index 91c91fcf3c24..c04420d5aa3d 100644
--- a/Makefile
+++ b/Makefile
@@ -1175,7 +1175,7 @@ include/config/kernel.release: FORCE
 # Carefully list dependencies so we do not try to build scripts twice
 # in parallel
 PHONY += scripts
-scripts: scripts_basic scripts_dtc
+scripts: include/generated/utsrelease.h scripts_basic scripts_dtc
 	$(Q)$(MAKE) $(build)=$(@)
 
 # Things we need to do before we recursively start building the kernel
diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
index 6f0aecad5d67..c29334669a16 100644
--- a/scripts/gcc-plugins/Makefile
+++ b/scripts/gcc-plugins/Makefile
@@ -64,5 +64,5 @@ $(foreach m, $(notdir $(plugin-multi)), $(eval $(obj)/$m: $(addprefix $(obj)/, $
 quiet_cmd_plugin_cxx_o_c = HOSTCXX $@
       cmd_plugin_cxx_o_c = $(HOSTCXX) $(plugin_cxxflags) -c -o $@ $<
 
-$(plugin-objs): $(obj)/%.o: $(src)/%.c FORCE
+$(plugin-objs): $(obj)/%.o: $(src)/%.c $(objdir)/include/generated/utsrelease.h FORCE
 	$(call if_changed_dep,plugin_cxx_o_c)

Both "include/generated/utsrelease.h" and "scripts" were same-level
deps, so they were racing. 

-- 
Kees Cook