On Tue, 2 Dec 2014, Pablo Neira Ayuso wrote:
> > diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
> > index 974ff38..8f51ba4 100644
> > --- a/net/netfilter/ipset/ip_set_hash_gen.h
> > +++ b/net/netfilter/ipset/ip_set_hash_gen.h
> > @@ -10,19 +10,19 @@
> >
> > #include <linux/rcupdate.h>
> > #include <linux/jhash.h>
> > +#include <linux/types.h>
> > #include <linux/netfilter/ipset/ip_set_timeout.h>
> > -#ifndef rcu_dereference_bh
> > -#define rcu_dereference_bh(p) rcu_dereference(p)
> > -#endif
> > +
> > +#define __ipset_dereference_protected(p, c) rcu_dereference_protected(p, c)
> > +#define ipset_dereference_protected(p, set) \
> > + __ipset_dereference_protected(p, spin_is_locked(&(set)->lock))
> >
> > #define rcu_dereference_bh_nfnl(p) rcu_dereference_bh_check(p, 1)
> >
> [...]
> > /* Flush a hash type of set: destroy all elements */
> > @@ -376,16 +359,16 @@ mtype_flush(struct ip_set *set)
> > struct hbucket *n;
> > u32 i;
> >
> > - t = rcu_dereference_bh_nfnl(h->table);
> > + t = ipset_dereference_protected(h->table, set);
> > for (i = 0; i < jhash_size(t->htable_bits); i++) {
> > - n = hbucket(t, i);
> > - if (n->size) {
> > - if (set->extensions & IPSET_EXT_DESTROY)
> > - mtype_ext_cleanup(set, n);
> > - n->size = n->pos = 0;
> > - /* FIXME: use slab cache */
> > - kfree(n->value);
> > - }
> > + n = __ipset_dereference_protected(hbucket(t, i), 1);
>
> What is your intention with these macros?
The macros serve to solve sparse checking warnings. Without the macros one
can get:
/usr/src/git/ipset/ipset/kernel/net/netfilter/ipset/ip_set_hash_gen.h:369:19:
warning: incorrect type in assignment (different address spaces)
/usr/src/git/ipset/ipset/kernel/net/netfilter/ipset/ip_set_hash_gen.h:369:19:
expected struct hbucket *n
/usr/src/git/ipset/ipset/kernel/net/netfilter/ipset/ip_set_hash_gen.h:369:19:
got struct hbucket [noderef] <asn:4>*<noident>
The real condition (spin is locked) is always checked before the loop, in
ipset_dereference_protected. Inside the loop it's not checked again and
again.
Best regards,
Jozsef
-
E-mail : kadlec@xxxxxxxxxxxxxxxxx, kadlecsik.jozsef@xxxxxxxxxxxxx
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
H-1525 Budapest 114, POB. 49, Hungary
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