From: Paul E. McKenney <paulmck@kernel.org>
To: kbuild-all@lists.01.org
Subject: Re: [bpf-next:master 15/30] kernel/bpf/devmap.c:1030:40: sparse: sparse: cast removes address space '__rcu' of expression
Date: Wed, 30 Jun 2021 08:38:00 -0700 [thread overview]
Message-ID: <20210630153800.GY4397@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <731df9e2-1db0-652d-d4ce-59cd5a4ad3b4@intel.com>
[-- Attachment #1: Type: text/plain, Size: 6428 bytes --]
On Wed, Jun 30, 2021 at 03:31:57PM +0800, Chen, Rong A wrote:
>
>
> 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
This looks similar to what I saw, and I believe that Toke sent out a
patch for these.
So this is likely to be an architecture-specific bug in IA64, correct?
I was going to add the IA64 maintainers on CC, but:
IA64 (Itanium) PLATFORM
L: linux-ia64(a)vger.kernel.org
S: Orphan
F: Documentation/ia64/
F: arch/ia64/
Over to you in your role as an Intel employee! ;-)
Thanx, Paul
prev parent reply other threads:[~2021-06-30 15:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-26 8:41 [bpf-next:master 15/30] kernel/bpf/devmap.c:1030:40: sparse: sparse: cast removes address space '__rcu' of expression kernel test robot
2021-06-26 10:00 ` Toke Høiland-Jørgensen
2021-06-28 15:53 ` Paul E. McKenney
2021-06-28 22:42 ` Toke Høiland-Jørgensen
2021-06-28 22:53 ` Paul E. McKenney
2021-06-29 8:47 ` Chen, Rong A
2021-06-29 16:57 ` Paul E. McKenney
2021-06-30 7:31 ` Chen, Rong A
2021-06-30 15:38 ` Paul E. McKenney [this message]
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