Messages in this thread |  | | | Date | Mon, 9 May 2011 09:17:57 -0700 | | From | Randy Dunlap <> | | Subject | Re: 2.6.39-rc6-mmotm0506 and -next - __kfree_rcu breaks third-party kernel code |
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On Mon, 09 May 2011 11:05:00 -0400 Valdis.Kletnieks@vt.edu wrote:
> So I have a third-party kernel module which wants to check what kernel version > it's building against, and it fails to build under -rc6-mmotm0506 (it works > just fine under -rc5-mmotm0429). > > I finally isolated it down to a two-liner section of code, which seems to die > because somebody didn't include something that rcupdate.h wanted to see: > > cat > /tmp/kernconf.c <<EOF > #include <linux/version.h> > #include <linux/utsname.h> > EOF > + cat > > # This builds fine > kern="2.6.39-rc5-mmotm0429" > + kern=2.6.39-rc5-mmotm0429 > cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I/lib/modules/${kern}/build/include -include /lib/modules/${kern}/build/include/generated/autoconf.h -I/lib/modules/${kern}/build/arch/x86/include -c /tmp/kernconf.c > + cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I/lib/modules/2.6.39-rc5-mmotm0429/build/include -include /lib/modules/2.6.39-rc5-mmotm0429/build/include/generated/autoconf.h -I/lib/modules/2.6.39-rc5-mmotm0429/build/arch/x86/include -c /tmp/kernconf.c > > # this one dies > kern="2.6.39-rc6-mmotm0506" > + kern=2.6.39-rc6-mmotm0506 > cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I/lib/modules/${kern}/build/include -include /lib/modules/${kern}/build/include/generated/autoconf.h -I/lib/modules/${kern}/build/arch/x86/include -c /tmp/kernconf.c > + cc -D__KERNEL__ -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.6.0/include -I/lib/modules/2.6.39-rc6-mmotm0506/build/include -include /lib/modules/2.6.39-rc6-mmotm0506/build/include/generated/autoconf.h -I/lib/modules/2.6.39-rc6-mmotm0506/build/arch/x86/include -c /tmp/kernconf.c > In file included from /lib/modules/2.6.39-rc6-mmotm0506/build/include/linux/sem.h:81:0, > from /lib/modules/2.6.39-rc6-mmotm0506/build/include/linux/sched.h:72, > from /lib/modules/2.6.39-rc6-mmotm0506/build/include/linux/utsname.h:35, > from /tmp/kernconf.c:2: > /lib/modules/2.6.39-rc6-mmotm0506/build/include/linux/rcupdate.h: In function '__kfree_rcu': > /lib/modules/2.6.39-rc6-mmotm0506/build/include/linux/rcupdate.h:822:2: error: size of unnamed array is negative > > rm /tmp/kernconf.c > + rm /tmp/kernconf.c > > 'git blame include/linux/rcudate.h' points at this commit: > > commit 896d4eb94e0b7cd896ee92c380fadc1e9d867cfc > Author: Lai Jiangshan <laijs@cn.fujitsu.com> > Date: Fri Mar 18 11:15:47 2011 +0800 > > rcu: introduce kfree_rcu()
I'd be happy to see a simple fix, but we don't generally support building external modules without using the kernel kbuild infrastructure AFAIK -- and when I add a Makefile along with your kernconf.c file, it builds successfully on mmotm-2011-0506-1639.
Makefile is: # usage: # cd /path/to/kernel/source/ && make SUBDIRS=/path/to/source/procfs_ex/ modules # aka: # make -C /path/to/kernel/source M=/path/to/module/source [O=/path/to/kernel/build] modules
obj-m := kernconf.o
clean-files := *.o *.ko *.mod.c ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ then: > make -C /lnx/src/MM/mmotm-2011-0506-1639 M=$PWD O=/lnx/src/MM/mmotm-2011-0506-1639/xx64 modules 2>&1 | tee bld1.out make: Entering directory `/lnx/src/MM/mmotm-2011-0506-1639' CC [M] /home/rddunlap/src/kernmodule/kernconf.o Building modules, stage 2. MODPOST 1 modules CC /home/rddunlap/src/kernmodule/kernconf.mod.o LD [M] /home/rddunlap/src/kernmodule/kernconf.ko make: Leaving directory `/lnx/src/MM/mmotm-2011-0506-1639'
done. --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***
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