ip: nexthop: add cache helpers

Add a static nexthop cache in a hash with 1024 buckets and helpers to
manage it (link, unlink, find, add nexthop, del nexthop). Adding new
nexthops is done by creating a new rtnl handle and using it to retrieve
the nexthop so the helper is safe to use while already reading a
response (i.e. using the global rth).

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>

diff --git a/ip/ipnexthop.c b/ip/ipnexthop.c
index 454c7416e30f10209f1b48d2ae39c8398c481adc..e0f0f78460c9a2a2454e4266afb0e229e81946d0 100644 (file)
--- a/ip/ipnexthop.c
+++ b/ip/ipnexthop.c
@@ -34,6 +34,8 @@ enum {
 #define RTM_NHA(h)  ((struct rtattr *)(((char *)(h)) + \
                        NLMSG_ALIGN(sizeof(struct nhmsg))))
 
+static struct hlist_head nh_cache[NH_CACHE_SIZE];
+
 static void usage(void) __attribute__((noreturn));
 
 static void usage(void)
@@ -504,6 +506,102 @@ static int  __ipnh_get_id(struct rtnl_handle *rthp, __u32 nh_id,
        return rtnl_talk(rthp, &req.n, answer);
 }
 
+static struct hlist_head *ipnh_cache_head(__u32 nh_id)
+{
+       nh_id ^= nh_id >> 20;
+       nh_id ^= nh_id >> 10;
+
+       return &nh_cache[nh_id % NH_CACHE_SIZE];
+}
+
+static void ipnh_cache_link_entry(struct nh_entry *nhe)
+{
+       struct hlist_head *head = ipnh_cache_head(nhe->nh_id);
+
+       hlist_add_head(&nhe->nh_hash, head);
+}
+
+static void ipnh_cache_unlink_entry(struct nh_entry *nhe)
+{
+       hlist_del(&nhe->nh_hash);
+}
+
+static struct nh_entry *ipnh_cache_get(__u32 nh_id)
+{
+       struct hlist_head *head = ipnh_cache_head(nh_id);
+       struct nh_entry *nhe;
+       struct hlist_node *n;
+
+       hlist_for_each(n, head) {
+               nhe = container_of(n, struct nh_entry, nh_hash);
+               if (nhe->nh_id == nh_id)
+                       return nhe;
+       }
+
+       return NULL;
+}
+
+static int __ipnh_cache_parse_nlmsg(const struct nlmsghdr *n,
+                                   struct nh_entry *nhe)
+{
+       int err, len;
+
+       len = n->nlmsg_len - NLMSG_SPACE(sizeof(struct nhmsg));
+       if (len < 0) {
+               fprintf(stderr, "BUG: wrong nlmsg len %d\n", len);
+               return -EINVAL;
+       }
+
+       err = ipnh_parse_nhmsg(stderr, NLMSG_DATA(n), len, nhe);
+       if (err) {
+               fprintf(stderr, "Error parsing nexthop: %s\n", strerror(-err));
+               return err;
+       }
+
+       return 0;
+}
+
+static struct nh_entry *ipnh_cache_add(__u32 nh_id)
+{
+       struct rtnl_handle cache_rth = { .fd = -1 };
+       struct nlmsghdr *answer = NULL;
+       struct nh_entry *nhe = NULL;
+
+       if (rtnl_open(&cache_rth, 0) < 0)
+               goto out;
+
+       if (__ipnh_get_id(&cache_rth, nh_id, &answer) < 0)
+               goto out;
+
+       nhe = malloc(sizeof(*nhe));
+       if (!nhe)
+               goto out;
+
+       if (__ipnh_cache_parse_nlmsg(answer, nhe))
+               goto out_free_nhe;
+
+       ipnh_cache_link_entry(nhe);
+
+out:
+       if (answer)
+               free(answer);
+       rtnl_close(&cache_rth);
+
+       return nhe;
+
+out_free_nhe:
+       free(nhe);
+       nhe = NULL;
+       goto out;
+}
+
+static void ipnh_cache_del(struct nh_entry *nhe)
+{
+       ipnh_cache_unlink_entry(nhe);
+       ipnh_destroy_entry(nhe);
+       free(nhe);
+}
+
 int print_nexthop(struct nlmsghdr *n, void *arg)
 {
        struct nhmsg *nhm = NLMSG_DATA(n);

diff --git a/ip/nh_common.h b/ip/nh_common.h
index d9730f45c6fb97e774a28ab4b153d8d22668d774..ee84d968d8dd605c522ec594e8736248bb0c60fc 100644 (file)
--- a/ip/nh_common.h
+++ b/ip/nh_common.h
@@ -2,6 +2,10 @@
 #ifndef __NH_COMMON_H__
 #define __NH_COMMON_H__ 1
 
+#include <list.h>
+
+#define NH_CACHE_SIZE          1024
+
 struct nha_res_grp {
        __u16                   buckets;
        __u32                   idle_timer;
@@ -10,6 +14,8 @@ struct nha_res_grp {
 };
 
 struct nh_entry {
+       struct hlist_node       nh_hash;
+
        __u32                   nh_id;
        __u32                   nh_oif;
        __u32                   nh_flags;