Re: [net-next:master 49/50] net/netfilter/nfnetlink_queue_ct.c:23:18: sparse: incompatible types in comparison expression (different address spaces)

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Jun 19, 2012 at 07:41:13PM +0800, Fengguang Wu wrote:
> On Tue, Jun 19, 2012 at 01:28:23PM +0200, Pablo Neira Ayuso wrote:
> > On Tue, Jun 19, 2012 at 02:00:50PM +0800, wfg@linux.intel.com wrote:
> > > Hi Pablo,
> > > 
> > > There are new sparse warnings show up in
> > > 
> > > tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
> > > head:   6bdc5f49e365a5403b9fdef01ceb37241ab00f9b
> > > commit: 7c62234547255ce4c385a218915965bc2f14fe45 [49/50] netfilter: nfnetlink_queue: fix compilation with NF_CONNTRACK disabled
> > > 
> > > All sparse warnings:
> > > 
> > > net/netfilter/nfnetlink_queue_ct.c:23:18: sparse: incompatible types in comparison expression (different address spaces)
> > > net/netfilter/nfnetlink_queue_ct.c:45:18: sparse: incompatible types in comparison expression (different address spaces)
> > > net/netfilter/nfnetlink_queue_ct.c:63:18: sparse: incompatible types in comparison expression (different address spaces)
> > > net/netfilter/nfnetlink_queue_ct.c:91:18: sparse: incompatible types in comparison expression (different address spaces)
> > > net/netfilter/nf_conntrack_netlink.c:1100:27: sparse: incompatible types in comparison expression (different address spaces)
> > > net/netfilter/nf_conntrack_netlink.c:1222:34: sparse: incompatible types in comparison expression (different address spaces)
> > > net/netfilter/nf_conntrack_netlink.c:1222:34: sparse: incompatible types in comparison expression (different address spaces)
> > > 
> > > net/netfilter/nfnetlink_queue_ct.c:23:
> > >     20		struct nf_conn *ct;
> > >     21	
> > >     22		/* rcu_read_lock()ed by __nf_queue already. */
> > >   > 23		nfq_ct = rcu_dereference(nfq_ct_hook);
> > >     24		if (nfq_ct == NULL)
> > >     25			return NULL;
> > >     26	
> > 
> > What CF options are you using to make sparse spot this? I cannot hit
> > those message here.
> 
> I don't specify any options. I do use the sparse compiled from latest
> git tree.
> 
>         git://git.kernel.org/pub/scm/devel/sparse/chrisl/sparse.git
> 
> And changed its code to output "sparse:" rather than "error:"/"warning:"
> so that they can be distinguished from the gcc error/warnings.

I don't hit those errors here with:

make C=2 net/netfilter/nfnetlink_queue_ct.o

using latest sparse from git tree.

I guess it's related to some missing __rcu tag, but I need to make
sure. I don't want to play whack-a-mole game ;-).

> > I've got a fix but I don't want to send you an untested patch.
> 
> Appreciated!
> 
> I run a special service for this. If you push a patch to your git tree
> containing the line
> 
>         Reported-by: Fengguang Wu <wfg@linux.intel.com>

yes, I always try to add that tag.

> And not containing any "Tested-by:" line, my script will automatically
> test it and send a success/failure notification back to you, normally
> within one hour.

Great to know.