On Mon, May 09, 2022 at 01:36:23PM -0700, Luis Chamberlain wrote: > The recent commit "bpf: Move BPF sysctls from kernel/sysctl.c to BPF core" > triggered 0-day to issue an email for what seems to have been an old > clang warning. So this issue should have existed before as well, from > what I can tell. The issue is that clang expects a forward declaration > for routines declared as weak while gcc does not. > > This can be reproduced with 0-day's x86_64-randconfig-c007 > https://download.01.org/0day-ci/archive/20220424/202204240008.JDntM9cU-lkp@xxxxxxxxx/config > > And using: > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 SHELL=/bin/bash kernel/bpf/syscall.o > Compiler will be installed in /home/mcgrof/0day > make --keep-going HOSTCC=/home/mcgrof/0day/clang/bin/clang CC=/home/mcgrof/0day/clang/bin/clang LD=/home/mcgrof/0day/clang/bin/ld.lld HOSTLD=/home/mcgrof/0day/clang/bin/ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-size READELF=llvm-readelf HOSTCXX=clang++ HOSTAR=llvm-ar CROSS_COMPILE=x86_64-linux-gnu- --jobs=24 W=1 ARCH=x86_64 SHELL=/bin/bash kernel/bpf/syscall.o > DESCEND objtool > CALL scripts/atomic/check-atomics.sh > CALL scripts/checksyscalls.sh > CC kernel/bpf/syscall.o > kernel/bpf/syscall.c:4944:13: warning: no previous prototype for function 'unpriv_ebpf_notify' [-Wmissing-prototypes] > void __weak unpriv_ebpf_notify(int new_state) > ^ > kernel/bpf/syscall.c:4944:1: note: declare 'static' if the function is not intended to be used outside of this translation unit > void __weak unpriv_ebpf_notify(int new_state) > ^ > static > > Fixes: 2900005ea287 ("bpf: Move BPF sysctls from kernel/sysctl.c to BPF core") > Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> > --- > > Daniel, > > Given what we did fore 2900005ea287 ("bpf: Move BPF sysctls from > kernel/sysctl.c to BPF core") where I had pulled pr/bpf-sysctl a > while ago into sysctl-next and then merged the patch in question, > should I just safely carry this patch onto sysctl-next? Let me know > how you'd like to proceed. > > Also, it wasn't clear if putting this forward declaration on > bpf.h was your ideal preference. After testing this on sysctl-testing without issues going to move this to sysctl-next now. Luis
