On 21/09/17 09:43, Jiri Pirko wrote:
> From: Yotam Gigi <yot...@mellanox.com>
>
> Next commits will introduce MFC notifications through the atomic
> fib_notification chain, thus allowing modules to be aware of MFC entries.
>
> Due to the fact that modules may need to hold a reference to an MFC entry,
> add reference count to MFC entries to prevent them from being freed while
> these modules use them.
>
> The reference counting is done only on resolved MFC entries currently.
>
> Signed-off-by: Yotam Gigi <yot...@mellanox.com>
> Reviewed-by: Ido Schimmel <ido...@mellanox.com>
> Signed-off-by: Jiri Pirko <j...@mellanox.com>
> ---
> include/linux/mroute.h | 20 ++++++++++++++++++++
> net/ipv4/ipmr.c | 8 +++++---
> 2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/mroute.h b/include/linux/mroute.h
> index d7f6333..2f88e3d 100644
> --- a/include/linux/mroute.h
> +++ b/include/linux/mroute.h
> @@ -138,6 +138,7 @@ struct mfc_cache {
> unsigned long wrong_if;
> unsigned long lastuse;
> unsigned char ttls[MAXVIFS];
> + refcount_t refcount;
There's a struct comment above that has a short description for each entry,
I know it seems redundant, but could you please add one for this ?
> } res;
> } mfc_un;
> struct list_head list;
> @@ -148,4 +149,23 @@ struct rtmsg;
> int ipmr_get_route(struct net *net, struct sk_buff *skb,
> __be32 saddr, __be32 daddr,
> struct rtmsg *rtm, u32 portid);
> +
> +#ifdef CONFIG_IP_MROUTE
> +void ipmr_cache_free(struct mfc_cache *mfc_cache);
> +#else
> +static inline void ipmr_cache_free(struct mfc_cache *mfc_cache)
> +{
> +}
> +#endif
> +
> +static inline void ipmr_cache_put(struct mfc_cache *c)
> +{
> + if (refcount_dec_and_test(&c->mfc_un.res.refcount))
> + ipmr_cache_free(c);
> +}
> +static inline void ipmr_cache_hold(struct mfc_cache *c)
> +{
> + refcount_inc(&c->mfc_un.res.refcount);
> +}
> +
> #endif
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index c9b3e6e..86dc5f9 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -652,10 +652,11 @@ static void ipmr_cache_free_rcu(struct rcu_head *head)
> kmem_cache_free(mrt_cachep, c);
> }
>
> -static inline void ipmr_cache_free(struct mfc_cache *c)
> +void ipmr_cache_free(struct mfc_cache *c)
> {
> call_rcu(&c->rcu, ipmr_cache_free_rcu);
> }
> +EXPORT_SYMBOL(ipmr_cache_free);
>
> /* Destroy an unresolved cache entry, killing queued skbs
> * and reporting error to netlink readers.
> @@ -949,6 +950,7 @@ static struct mfc_cache *ipmr_cache_alloc(void)
> if (c) {
> c->mfc_un.res.last_assert = jiffies - MFC_ASSERT_THRESH - 1;
> c->mfc_un.res.minvif = MAXVIFS;
> + refcount_set(&c->mfc_un.res.refcount, 1);
> }
> return c;
> }
> @@ -1162,7 +1164,7 @@ static int ipmr_mfc_delete(struct mr_table *mrt, struct
> mfcctl *mfc, int parent)
> rhltable_remove(&mrt->mfc_hash, &c->mnode, ipmr_rht_params);
> list_del_rcu(&c->list);
> mroute_netlink_event(mrt, c, RTM_DELROUTE);
> - ipmr_cache_free(c);
> + ipmr_cache_put(c);
>
> return 0;
> }
> @@ -1264,7 +1266,7 @@ static void mroute_clean_tables(struct mr_table *mrt,
> bool all)
> rhltable_remove(&mrt->mfc_hash, &c->mnode, ipmr_rht_params);
> list_del_rcu(&c->list);
> mroute_netlink_event(mrt, c, RTM_DELROUTE);
> - ipmr_cache_free(c);
> + ipmr_cache_put(c);
> }
>
> if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
>
