"Support post-3.13 kthread_create() semantics." breaks 3.13.7 builds on Gentoo with GCC 4.8.2

[ryao]

The recently merged 17a527c breaks building on Gentoo with GCC 4.8.2:

In file included from /var/tmp/portage/sys-kernel/spl-9999/work/spl-9999/module/spl/../../module/spl/spl-thread.c:27:0:
/var/tmp/portage/sys-kernel/spl-9999/work/spl-9999/module/spl/../../module/spl/spl-thread.c: In function ‘spl_kthread_create’:
/var/tmp/portage/sys-kernel/spl-9999/work/spl-9999/include/sys/thread.h:69:1: error: function ‘spl_kthread_create’ can never be inlined because it uses variable argument lists
 spl_kthread_create(int (*func)(void *), void *data, const char namefmt[], ...)

[DeHackEd]

Also affects RHEL 6 builds

# gcc -v
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC) 

[behlendorf]

I'll get this fixed right away or revert the offending patch until we can rework it.

[dweeezil]

Strangely enough, it does build under CentOS 6.4 with gcc 4.4.7.

I suppose this wrapper should be a regular function.

[dweeezil]

Converted it into a regular function in dweeezil/spl@31e5b58. Still wondering why I don't get errors on my CentOS 6.4 system even with --enable-debug.

[ryao]

@dweeezil I suspect that the regression is compiler specific.

[behlendorf]

Thanks for the updated patch. I am able to reproduce the error with CentOS 6.5.

[dweeezil]

@behlendorf I presume the de-inlined version does build properly?

I guess I need to rig up a newer CentOS test system.

[behlendorf]

@dweeezil Yes the updated patched worked fine under CentOS 6.5 and I've merged it. I wasn't able to verify the fix on Gentoo but this should have fixed it. @ryao please let us know if that somehow is not the case.