Re: Dealing with SUBLEVEL overflow in backports

在2022年2月10日二月 上午8:17，Johannes Berg写道：
> On Thu, 2022-02-10 at 00:44 +0100, Hauke Mehrtens wrote:
>> 
>> What build problem do you get when you include "#include <linux/bug.h>" 
>> here on kernel 4.9.299?
>> 
>
> I haven't tried, but per the explanation, you get issues if you tried to
> include bug.h in the first place, since then you get
>
> bug.h
> -> includes build_bug.h (since the patch)
> -> uses build_bug.h from backports
> -> includes bug.h (does nothing, double include)
>

Yep that's the problem.

What I'm trying is something like:
Though it won't work in kernel intergration mode. My makefile foo does not
allow me to come up a idea.

diff --git a/backport/Makefile.real b/backport/Makefile.real
index 65508028..26482e52 100644
--- a/backport/Makefile.real
+++ b/backport/Makefile.real
@@ -83,8 +83,19 @@ backport-include/backport/autoconf.h: .config Kconfig.versions Kconfig.kernel
        ) > backport-include/backport/autoconf.h
        @echo " done."
 
+.PHONY: backport-include/backport/version.h
+backport-include/backport/version.h:
+       @echo -n "Building backport-include/backport/version.h ..."
+       @echo "#ifndef COMPAT_VERSION_INCLUDED" > $@
+       @echo "#define COMPAT_VERSION_INCLUDED" >> $@
+       @echo '#define COMPAT_LINUX_VERSION $(VERSION)' >> $@
+       @echo '#define COMPAT_LINUX_PATCHLEVEL $(PATCHLEVEL)' >> $@
+       @echo '#define COMPAT_LINUX_SUBLEVEL $(SUBLEVEL)' >> $@
+       @echo "#endif" >> $@
+       @echo " done."
+
 .PHONY: modules
-modules: backport-include/backport/autoconf.h
+modules: backport-include/backport/autoconf.h backport-include/backport/version.h
        @$(MAKE) -f Makefile.build modules
 
 .PHONY: install
diff --git a/backport/backport-include/linux/version.h b/backport/backport-include/linux/version.h
index 2cb601ad..06684ffa 100644
--- a/backport/backport-include/linux/version.h
+++ b/backport/backport-include/linux/version.h
@@ -1,5 +1,7 @@
 #ifndef _BP_LINUX_VERSION_H
 #define _BP_LINUX_VERSION_H
+
+#include <backport/version.h>
 #include_next <linux/version.h>
 
 #ifndef RHEL_RELEASE_VERSION
@@ -10,8 +12,17 @@
 #define RHEL_RELEASE_CODE 0
 #endif
 
-#define LINUX_VERSION_IS_LESS(x1,x2,x3)        (LINUX_VERSION_CODE < KERNEL_VERSION(x1,x2,x3))
-#define LINUX_VERSION_IS_GEQ(x1,x2,x3) (LINUX_VERSION_CODE >= KERNEL_VERSION(x1,x2,x3))
+#define COMPACT_KERNEL_VERSION(a,b,c) (((a) << 24) + ((b) << 16) + (c))
+
+#define COMPACT_LINUX_VERSION_CODE                       \
+       COMPACT_KERNEL_VERSION(COMPAT_LINUX_VERSION,     \
+                               COMPAT_LINUX_PATCHLEVEL, \
+                               COMPAT_LINUX_SUBLEVEL)
+
+#define LINUX_VERSION_IS_LESS(x1,x2,x3)        \
+       (COMPACT_LINUX_VERSION_CODE < COMPACT_KERNEL_VERSION(x1,x2,x3))
+#define LINUX_VERSION_IS_GEQ(x1,x2,x3) \
+       (COMPACT_LINUX_VERSION_CODE >= COMPACT_KERNEL_VERSION(x1,x2,x3))
 #define LINUX_VERSION_IN_RANGE(x1,x2,x3, y1,y2,y3) \
        (LINUX_VERSION_IS_GEQ(x1,x2,x3) && LINUX_VERSION_IS_LESS(y1,y2,y3))
 #endif /* _BP_LINUX_VERSION_H */

[...]
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- Jiaxun
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