Re: [PATCH 2/2] kvm: mmu: page_track: Fix RCU list API usage

[Naresh Kamboju]

Hi Paul,

> I am not seeing this here.

Do you notice any warnings while building linux next master
for x86_64 architecture ?

> Could you please let us know what compiler
> and command-line options you are using to generate this?

We have two build systems one showing it as error and build breaks
and another one showing it as warning and build pass.
tool chain: gcc 9.3.0
build command:
make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=x86 HOSTCC=gcc
CC="sccache gcc" O=build

metadata:
    git_repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git,
    target_arch: x86,
    toolchain: gcc-9,
    git_short_log: aab7ee9f8ff0 (\Add linux-next specific files for 20200717\),
    git_sha: aab7ee9f8ff0110bfcd594b33dc33748dc1baf46,
    git_describe: next-20200717,
    kernel_version: 5.8.0-rc5,

warning log,
--
make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=x86 HOSTCC=gcc
CC="sccache gcc" O=build
#
In file included from ../include/linux/pid.h:5,
                 from ../include/linux/sched.h:14,
                 from ../include/linux/kvm_host.h:12,
                 from ../arch/x86/kvm/mmu/page_track.c:14:
../arch/x86/kvm/mmu/page_track.c: In function âkvm_page_track_writeâ:
../include/linux/rculist.h:727:30: warning: left-hand operand of comma
expression has no effect [-Wunused-value]
  727 |  for (__list_check_srcu(cond),     \
      |                              ^
../arch/x86/kvm/mmu/page_track.c:232:2: note: in expansion of macro
âhlist_for_each_entry_srcuâ
  232 |  hlist_for_each_entry_srcu(n, &head->track_notifier_list, node,
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~
../arch/x86/kvm/mmu/page_track.c: In function âkvm_page_track_flush_slotâ:
../include/linux/rculist.h:727:30: warning: left-hand operand of comma
expression has no effect [-Wunused-value]
  727 |  for (__list_check_srcu(cond),     \
      |                              ^
../arch/x86/kvm/mmu/page_track.c:258:2: note: in expansion of macro
âhlist_for_each_entry_srcuâ
  258 |  hlist_for_each_entry_srcu(n, &head->track_notifier_list, node,
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/kvm/svm/svm.o: warning: objtool: svm_flush_tlb_gva()+0x12:
call without frame pointer save/setup
kernel/bpf/core.o: warning: objtool: ___bpf_prog_run.cold()+0x7: call
without frame pointer save/setup

ref:
https://gitlab.com/Linaro/lkft/kernel-runs/-/jobs/643978120


>                                                         Thanx, Paul

- Naresh