Re: nolibc patches, still possible for 6.5 ?

[Willy Tarreau]

Hello Paul,

On Sun, Jun 04, 2023 at 03:57:54PM -0700, Paul E. McKenney wrote:
> On Sun, Jun 04, 2023 at 03:20:11PM +0200, Willy Tarreau wrote:
> > Hello Paul,
> > 
> > Thomas and Zhangjin have provided significant nolibc cleanups, and
> > fixes, as well as preparation work to later support riscv32.
> > 
> > These consist in the following main series:
> >   - generalization of stackprotector to other archs that were not
> >     previously supported (riscv, mips, loongarch, arm, arm64)
> > 
> >   - general cleanups of the makefile, test report output, deduplication
> >     of certain tests
> > 
> >   - slightly better compliance of some tests performed on certain syscalls
> >     (e.g. no longer pass (void*)1 to gettimeofday() since glibc hates it).
> > 
> >   - add support for nanoseconds in stat() and statx()
> > 
> >   - fixes for some syscalls (e.g. ppoll() has 5 arguments not 4)
> > 
> >   - fixes around limits.h and  INT_MAX / INT_FAST64_MAX
> > 
> > I rebased the whole series on top of your latest dev branch (d19a9ca3d5)
> > and it works fine for all archs.
> > 
> > I don't know if you're still planning on merging new stuff in this area
> > for 6.5 or not (since I know that it involves new series of tests on your
> > side as well), but given that Zhangjin will engage into deeper changes
> > later for riscv32 that will likely imply to update more syscalls to use
> > the time64 ones, I would prefer to split the cleanups from the hard stuff,
> > but I'll let you judge based on the current state of what's pending for
> > 6.5.
> > 
> > In any case I'm putting all this here for now (not for merge yet):
> > 
> >    git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git 20230604-nolibc-rv32+stkp6
> > 
> > I'd like Thomas and Zhangjin to perform a last check to confirm they're
> > OK with this final integration.
> 
> Given that the testing converges by the end of this week, I can't see
> any reason why these cannot make v6.5.  (There were some kernel test
> robot complaints as well, valid or not I am not sure.)

After Thomas' and Zhangjin's reviews and checks, I could run a mostly
complete check:
  - arm64, i386, x86_64 show 100% success
  - arm, mips: 100% success, stackprotector skipped
  - s390x, riscv64: run-user OK, kernel build fails (see below)
  - loongarch: build OK, just not executed (need to upgrade my qemu
    and I hate doing it late when some tests results are needed)

Regarding the build failure affecting s390x and riscv64, it's a regular
kernel resulting from "make defconfig". For both archs, I'm getting this
failure:

  In file included from kernel/rcu/update.c:649:
  kernel/rcu/tasks.h: In function 'get_rcu_tasks_gp_kthread':
    CC      fs/kernfs/dir.o
    CC      security/bpf/hooks.o
  kernel/rcu/tasks.h:1939:16: error: 'rcu_tasks' undeclared (first use in this function)
   1939 |         return rcu_tasks.kthread_ptr;
        |                ^~~~~~~~~
  kernel/rcu/tasks.h:1939:16: note: each undeclared identifier is reported only once for each function it appears in
  kernel/rcu/tasks.h:1940:1: error: control reaches end of non-void function [-Werror=return-type]
   1940 | }
        | ^
  cc1: some warnings being treated as errors

I rebased the branch on top of 6.4-rc5 and got the same. I'm building
with gcc-11.3.0 from kernel.org. I'm not sure whether this comes from
my build environment or recent changes to the kernel, but I'm sure I
haven't seen that error during 6.3-rc cycle. However, given that
Zhangjin seems to have successfully built it for riscv, there might
be something odd on my side.

Given that this build issue is not dependent on the selftest, I'm fine
with the branch getting merged as-is, and can provide feedback on this
build error if needed:

  git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git 20230606-nolibc-rv32+stkp7a

Just let me know if you prefer that I resend the whole series or need
more info etc, as usual.

Thank you!
Willy