Re: [stable:linux-4.19.y 2317/9999] lib/mpi/generic_mpih-mul2.c:49:24: error: invalid use of a cast in a inline asm context requiring an lvalue: remove the cast or build with -fheinous-gnu-extensions

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Aug 01, 2023 at 01:26:02PM -0700, Nathan Chancellor wrote:
> On Tue, Aug 01, 2023 at 01:15:30PM -0700, Nick Desaulniers wrote:
> > On Sun, Jul 30, 2023 at 8:57 PM kernel test robot <lkp@intel.com> wrote:
> > >
> > > Hi Fangrui,
> > >
> > > First bad commit (maybe != root cause):
> > >
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-4.19.y
> > > head:   767049cead76cf699707290d5aeefb3e4d0d5b43
> > > commit: 69c122751164c3c343eea205fd5c3e1d5132f967 [2317/9999] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross compilation
> > 
> > These aren't a result of Fangrui's change.  Fangrui's change probably
> > allows this config to mostly build, modulo the below error in
> > lib/mpi/generic_mpih-mul2.c.
> > 
> > > config: mips-randconfig-r036-20230731 (https://download.01.org/0day-ci/archive/20230731/202307311111.jPEdYIJR-lkp@intel.com/config)
> > > compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
> > > reproduce: (https://download.01.org/0day-ci/archive/20230731/202307311111.jPEdYIJR-lkp@intel.com/reproduce)
> > >
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202307311111.jPEdYIJR-lkp@intel.com/
> > >
> > > All error/warnings (new ones prefixed by >>):
> > >
> > > >> drivers/net/netdevsim/netdev.c:167:35: warning: unused variable 'nsim_switchdev_ops' [-Wunused-const-variable]
> > >      167 | static const struct switchdev_ops nsim_switchdev_ops = {
> > >          |                                   ^
> > >    1 warning generated.
> > 
> > ^ fixed by
> > commit e58df56c8564 ("netdevsim: Implement ndo_get_port_parent_id()")
> > in v5.1-rc1 (this report is against 4.19.y)
> > Florian, does it make sense for the stable maintainers to cherry-pick
> > e58df56c8564 to 4.19.y in isolation?
> > 
> > > --
> > > >> lib/mpi/generic_mpih-mul2.c:49:24: error: invalid use of a cast in a inline asm context requiring an lvalue: remove the cast or build with -fheinous-gnu-extensions
> > >       49 |                 umul_ppmm(prod_high, prod_low, s1_ptr[j], s2_limb);
> > >          |                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 
> > Looks like randconfig found and outstanding issue. Filed:
> > https://github.com/ClangBuiltLinux/linux/issues/1898 to follow up+fix.
> 
> Actually, this is fixed with commit b0c091ae04f6 ("lib/mpi: Eliminate
> unused umul_ppmm definitions for MIPS"), which applies cleanly to 4.19
> and should be fine because 4.19 contains commit cafa0010cd51 ("Raise the
> minimum required gcc version to 4.6").
> 
> Greg and Sasha, could b0c091ae04f6 be applied to 4.19 to resolve this
> randconfig failure?

Sure, I've applied this now to 4.19.y and 4.14.y for the next round of
releases.

thanks,

greg k-h