On Tue, Jun 29, 2021 at 04:47:17PM +0800, Chen, Rong A wrote:
> 
> 
> On 6/29/2021 6:53 AM, Paul E. McKenney wrote:
> > On Tue, Jun 29, 2021 at 12:42:52AM +0200, Toke Høiland-Jørgensen wrote:
> > > "Paul E. McKenney" <paulmck@kernel.org> writes:
> > > 
> > > > On Sat, Jun 26, 2021 at 12:00:55PM +0200, Toke Høiland-Jørgensen wrote:
> > > > > +Paul - any idea why unrcu_pointer() isn't working here?
> > > > 
> > > > Hello, Toke!
> > > > 
> > > > My distro version of sparse core-dumped before getting that far along.
> > > > 
> > > > I cloned and built the latest version, and got only the following errors
> > > > from kernel/bpf/devmap.c:
> > > > 
> > > > ------------------------------------------------------------------------
> > > > 
> > > >    CHECK   scripts/mod/empty.c
> > > >    CALL    scripts/checksyscalls.sh
> > > >    CALL    scripts/atomic/check-atomics.sh
> > > >    DESCEND objtool
> > > >    CC      kernel/bpf/devmap.o
> > > >    CHECK   kernel/bpf/devmap.c
> > > > kernel/bpf/devmap.c:561:29: warning: incorrect type in assignment (different address spaces)
> > > > kernel/bpf/devmap.c:561:29:    expected struct bpf_dtab_netdev *dst
> > > > kernel/bpf/devmap.c:561:29:    got struct bpf_dtab_netdev [noderef] __rcu *
> > > > kernel/bpf/devmap.c:657:29: warning: incorrect type in assignment (different address spaces)
> > > > kernel/bpf/devmap.c:657:29:    expected struct bpf_dtab_netdev *dst
> > > > kernel/bpf/devmap.c:657:29:    got struct bpf_dtab_netdev [noderef] __rcu *
> > > 
> > > Hmm, but those shouldn't be there either. Seems I missed those when
> > > rebasing, will send a follow-up patch...
> > 
> > Just check out different versions of sparse and average the results?  ;-)
> > 
> > 							Thanx, Paul
> 
> Hi Paul,
> 
> I tested the original attached config with the reproduce step, and I can
> reproduce the warning:
> 
> $ COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1
> CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=ia64 kernel/bpf/
> ...
> kernel/bpf/devmap.c:561:29: sparse: warning: incorrect type in assignment
> (different address spaces)
> kernel/bpf/devmap.c:561:29: sparse:    expected struct bpf_dtab_netdev *dst
> kernel/bpf/devmap.c:561:29: sparse:    got struct bpf_dtab_netdev [noderef]
> __rcu *
> kernel/bpf/devmap.c:657:29: sparse: warning: incorrect type in assignment
> (different address spaces)
> kernel/bpf/devmap.c:657:29: sparse:    expected struct bpf_dtab_netdev *dst
> kernel/bpf/devmap.c:657:29: sparse:    got struct bpf_dtab_netdev [noderef]
> __rcu *
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> kernel/bpf/devmap.c:1030:40: sparse: warning: cast removes address space
> '__rcu' of expression
> 
> and sparse is from latest master branch:
> $ sparse --version
> v0.6.3-341-g8af24329

OK, we really are running the same sparse.  And even the same gcc.

I did only a "make defconfig" followed by a "C=2" native build
on x86.  Is your "ARCH=ia64" required, or does sparse also get
you these same errors on x86?

							Thanx, Paul