On Mon, 2008-04-07 at 19:11 -0400, Paul Moore wrote:
> When adding new entries to the network node cache we would walk the entire
> hash bucket to make sure we didn't cross a threshold (done to bound the cache
> size). This isn't a very quick or elegant solution for something which is
> supposed to be quick-ish so add a counter to each hash bucket to track the
> size of the bucket and eliminate the need to walk the entire bucket list on
> each add.
>
> Signed-off-by: Paul Moore <paul.moore@xxxxxx>
> ---
>
> security/selinux/netnode.c | 57 +++++++++++++++++++++-----------------------
> 1 files changed, 27 insertions(+), 30 deletions(-)
>
> diff --git a/security/selinux/netnode.c b/security/selinux/netnode.c
> index f3c526f..b3a5a65 100644
> --- a/security/selinux/netnode.c
> +++ b/security/selinux/netnode.c
> @@ -40,11 +40,17 @@
> #include <net/ipv6.h>
> #include <asm/bug.h>
>
> +#include "netnode.h"
> #include "objsec.h"
>
> #define SEL_NETNODE_HASH_SIZE 256
> #define SEL_NETNODE_HASH_BKT_LIMIT 16
>
> +struct sel_netnode_bkt {
> + u32 size;
Technically this could just be an ordinary unsigned int, right?
We tend to overuse fixed-size integers in our code at present.
> + struct list_head list;
> +};
> +
> struct sel_netnode {
> struct netnode_security_struct nsec;
>
> @@ -179,35 +183,22 @@ static int sel_netnode_insert(struct sel_netnode *node)
> default:
> BUG();
> }
> - list_add_rcu(&node->list, &sel_netnode_hash[idx]);
>
> /* we need to impose a limit on the growth of the hash table so check
> * this bucket to make sure it is within the specified bounds */
> - list_for_each_entry(iter, &sel_netnode_hash[idx], list)
> - if (++count > SEL_NETNODE_HASH_BKT_LIMIT) {
> - list_del_rcu(&iter->list);
> - call_rcu(&iter->rcu, sel_netnode_free);
> - break;
> - }
> + list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
> + if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
> + struct sel_netnode *tail;
> + tail = list_entry(node->list.prev, struct sel_netnode, list);
> + __list_del(node->list.prev, node->list.next);
Can you clarify the change from list_del_rcu() to __list_del() here?
> + call_rcu(&tail->rcu, sel_netnode_free);
> + } else
> + sel_netnode_hash[idx].size++;
>
> return 0;
> }
--
Stephen Smalley
National Security Agency
--
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