On 6/30/2021 12:57 AM, Paul E. McKenney wrote:
> 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
> 

Hi Paul,

I can't get the error on x86:

$ make --jobs=16 C=1 CF=-fdiagnostic-prefix -D__CHECK_ENDIAN__ W=1 
ARCH=x86_64 kernel/bpf/
   DESCEND objtool
   CALL    scripts/atomic/check-atomics.sh
   CALL    scripts/checksyscalls.sh
   CC      kernel/bpf/devmap.o
   CHECK   kernel/bpf/devmap.c
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 *
   AR      kernel/bpf/built-in.a

Best Regards,
Rong Chen