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Date: Fri, 21 Jan 2011 17:36:57 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] neigh: __rcu annotations
On Thu, Jan 20, 2011 at 09:02:47AM +0100, Eric Dumazet wrote:
> fix some minor issues and sparse (__rcu) warnings
>
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> ---
> net/core/neighbour.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 60a9029..799f06e 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -316,7 +316,7 @@ static struct neigh_hash_table *neigh_hash_alloc(unsigned int entries)
> {
> size_t size = entries * sizeof(struct neighbour *);
> struct neigh_hash_table *ret;
> - struct neighbour **buckets;
> + struct neighbour __rcu **buckets;
>
> ret = kmalloc(sizeof(*ret), GFP_ATOMIC);
> if (!ret)
> @@ -324,14 +324,14 @@ static struct neigh_hash_table *neigh_hash_alloc(unsigned int entries)
> if (size <= PAGE_SIZE)
> buckets = kzalloc(size, GFP_ATOMIC);
> else
> - buckets = (struct neighbour **)
> + buckets = (struct neighbour __rcu **)
> __get_free_pages(GFP_ATOMIC | __GFP_ZERO,
> get_order(size));
> if (!buckets) {
> kfree(ret);
> return NULL;
> }
> - rcu_assign_pointer(ret->hash_buckets, buckets);
> + ret->hash_buckets = buckets;
> ret->hash_mask = entries - 1;
> get_random_bytes(&ret->hash_rnd, sizeof(ret->hash_rnd));
> return ret;
> @@ -343,7 +343,7 @@ static void neigh_hash_free_rcu(struct rcu_head *head)
> struct neigh_hash_table,
> rcu);
> size_t size = (nht->hash_mask + 1) * sizeof(struct neighbour *);
> - struct neighbour **buckets = nht->hash_buckets;
> + struct neighbour __rcu **buckets = nht->hash_buckets;
>
> if (size <= PAGE_SIZE)
> kfree(buckets);
> @@ -1540,7 +1540,7 @@ void neigh_table_init_no_netlink(struct neigh_table *tbl)
> panic("cannot create neighbour proc dir entry");
> #endif
>
> - tbl->nht = neigh_hash_alloc(8);
> + RCU_INIT_POINTER(tbl->nht, neigh_hash_alloc(8));
>
> phsize = (PNEIGH_HASHMASK + 1) * sizeof(struct pneigh_entry *);
> tbl->phash_buckets = kzalloc(phsize, GFP_KERNEL);
> @@ -1602,7 +1602,8 @@ int neigh_table_clear(struct neigh_table *tbl)
> }
> write_unlock(&neigh_tbl_lock);
>
> - call_rcu(&tbl->nht->rcu, neigh_hash_free_rcu);
> + call_rcu(&rcu_dereference_protected(tbl->nht, 1)->rcu,
> + neigh_hash_free_rcu);
Hello, Eric,
Any chance of a comment? Perhaps something like:
/*
* Because this has been removed from the list, no other updater
* can access this element.
*/
Thanx, Paul
> tbl->nht = NULL;
>
> kfree(tbl->phash_buckets);
>
>
> --
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